CN108871639B

CN108871639B - Center shaft moment detection system

Info

Publication number: CN108871639B
Application number: CN201810428667.XA
Authority: CN
Inventors: 夏静满; 胡江勇; 李家成
Original assignee: Chongqing Sanyehua Technology Co ltd
Current assignee: ANANDA DRIVE TECHNOLOGY (JIANGSU) Co.,Ltd.
Priority date: 2018-05-07
Filing date: 2018-05-07
Publication date: 2020-10-16
Anticipated expiration: 2038-05-07
Also published as: CN108871639A

Abstract

The invention relates to the technical field of moped driving, and particularly discloses a middle shaft torque detection system which comprises a sleeve, a deformation bridge and a circuit board, wherein the sleeve is arranged on the middle shaft; the deformation bridge is provided with a strain gauge unit; one end of the deformation bridge is fixedly connected with the middle shaft, and the other end of the deformation bridge is suspended in the air; the sleeve comprises a mounting sleeve moving relative to the middle shaft; a multi-pole magnetic ring and a double-Hall assembly which can synchronously generate relative motion along with the rotation of the middle shaft are arranged between the mounting sleeve and the middle shaft; the multi-pole magnetic ring comprises a plurality of N poles and S poles which are connected with each other; the double-Hall assembly comprises two unipolar switch Hall devices, and the two unipolar switch Hall devices can move relatively along the circumference of the multi-pole magnetic ring; one of two unipolar switches in the double-Hall assembly senses an N pole and the other senses an S pole; this application can accurate detection obtain moment.

Description

Center shaft moment detection system

Technical Field

The invention relates to the technical field of moped driving, in particular to a system for detecting the torque of a middle shaft of a moped.

Background

The power-assisted bicycle is also called a power-assisted electric bicycle, is a riding tool between a bicycle and an electric vehicle, provides kinetic energy required by the bicycle in advancing by electric power assisted manpower, and is a product of pursuing a high-efficiency, convenient, healthy and environment-friendly living mode for people.

The middle shaft is a structure which is used for connecting two pedals on the power-assisted bicycle and driving the clamping jaws and the chains on the clamping jaws to rotate, and is a core component of the power-assisted bicycle and used for driving and controlling the whole bicycle to normally run. When a rider rides the bicycle, the pedal is pedaled to drive the middle shaft to rotate, so that the claw connected with the middle shaft is driven to rotate, the claw drives the chain to rotate, and the chain drives the tire to rotate. When the power applied to the bicycle is greater than the power of the resistance, the bicycle can be driven to move forward. In order to reduce the work load of a rider and enable the rider to ride easily and laborsavingly, the output power of a person needs to be detected and determined, then the output power which the power-assisted bicycle needs to provide is calculated, and the power which is generated by the power-assisted bicycle and the rider together overcomes the power generated by resistance. Whereas the human output power is proportional to the product of the torque and the pedaling frequency. The torque here refers to the torque moment of the center shaft, and the pedaling frequency refers to the frequency at which the rider pedals the pedals. In order to accurately detect the output power of the current person, a middle shaft moment detection system is required to be arranged.

At present, the following center shaft torque system detection systems are mainly available:

the speed type false power-assisted sensor is adopted, and the actual speed of the power-assisted bicycle only detected does not detect the moment of the middle shaft, so that the power-assisted bicycle provides power-assisted force which is far different from the actually required power-assisted force, and the precision is low and the effect is poor.

Secondly, a set of elastic elements is arranged between the middle shaft and the chain wheel or between the motor and the flywheel, and the corresponding mechanical action is pushed by utilizing the slip displacement after the elastic elements are deformed by force, so that the physical quantity change such as a magnetic field, light quantity and the like generated between the elastic elements and the static sensing device is converted into electric quantity, and the pedaling force of the cyclist is detected; the elastic element is pushed to do mechanical action after being deformed, and the elastic element inevitably encounters resistance to limit the amplitude of the deformation and the mechanical action, so that the originally weak detection signal is further reduced, the detection sensitivity is low, and the consistency and the stability are poor; in addition, the elastic member is deformed irreversibly after a long time, resulting in further deterioration of the detection accuracy.

Thirdly, a set of elastic element is arranged between the middle shaft and the chain wheel or between the motor and the flywheel, pulse generating devices are respectively arranged at two ends of the elastic element, the phase difference is generated between the two pulse strings by utilizing the slip displacement after the elastic element is stressed and deformed, and the riding pedaling force is detected through the conversion of a phase discrimination circuit; because different pedaling frequencies produce different pulse frequencies, resulting in the same force corresponding to different phase differences, the algorithm is complicated and has poor consistency.

A deformation body is arranged between the rotating center shaft and the chain wheel bracket, a strain gauge is directly adhered, and an amplifying circuit is arranged and connected with the outside by a slip ring and an electric brush; the sensor in such a detection system is rotating all the time, and the slip ring and the brush generate unrecoverable loss during the rotation, resulting in short service life and poor durability of the sensor.

A deformation body is arranged between the rotating middle shaft and the chain wheel bracket, and special materials are adhered on the deformation body, so that the deformation body generates magnetic conduction change after being stressed to cause the inductance change of a coil group which is matched with the deformation body and does not rotate with the deformation body, and the deformation body is converted into corresponding electric quantity by detecting inductance or coupling coefficient; the detection system has the disadvantages of complex process and high cost.

Sixthly, a movable pressing wheel is arranged on a main loop of the chain, the displacement of the pressing wheel under the tension of the chain is detected, physical quantity changes such as magnetic fields, light quantity and the like are generated between the movable pressing wheel and a static sensing device and are converted into electric quantity, and the pedaling force of a rider is detected through linear conversion; the detection system is poor in universality and consistency, effects can be achieved only by special matching of the vehicle frame, and certain vehicle types cannot be used.

In conclusion, the conventional center shaft torque detection system cannot accurately acquire the torque of the center shaft, so that the output power of a rider cannot be accurately detected, the power-assisted bicycle cannot accurately provide power assistance, and finally the use effect of the power-assisted bicycle is poor.

When a rider pedals the pedals, the crank moves circularly to form a power torque applied to the crank by the rider, and the crank drives the middle shaft to rotate in the rotating process to form a torque of the middle shaft. However, when the crank rotates to some rotation angles, the effective force arm is very small, so that the pedaling force of a rider pedaling cannot be completely used for forming the power torque, and if the pedaling force is suddenly and greatly increased by the rider at the rotation angle positions, the change of the power torque is very small, so that the torque of the central shaft cannot accurately and timely respond, and the poor riding experience is brought to the rider. However, the existing bottom bracket moment detection system does not take any effective measures against the problem.

Disclosure of Invention

The invention aims to provide a middle axle torque detection system which can respond timely according to the change of the pedaling force of a rider.

In order to achieve the above purpose, the following scheme is provided:

the first scheme is as follows: the middle shaft torque detection system comprises a two-pole magnetic ring, a bipolar linear Hall and a circuit board;

one of the two-pole magnetic ring and the bipolar linear Hall is arranged on the middle shaft and rotates along with the middle shaft, and the other one is arranged in a static way relative to the middle shaft; the two-pole magnetic ring comprises an N pole and an S pole which are same in shape and connected with each other to form a ring-shaped section; the bipolar linear Hall device can move relatively along the circumferences of the two polar magnetic rings; the circuit board receives an electric signal representing the rotation angle of the crank from the bipolar linear Hall.

The noun explains:

bipolar linear hall: the bipolar linear Hall sensor can sense an N pole and an S pole, the voltages generated by induction are continuously represented by continuous curves along with the difference of induction magnetic poles and the difference of magnetic pole positions, and when the S pole and the N pole are semicircular and have the same length, the voltage change curves sensed by the bipolar linear Hall sensor are sine or cosine curves.

The working principle and the advantages of the invention are as follows:

the arrangement of the two-pole magnetic ring and the bipolar linear Hall enables the rotation angle of the crank to be accurately detected, and because the two magnetic poles of the two-pole magnetic ring are the same in shape and form the annular cross section, when a rider pedals the pedal with the same force to enable the crank to complete a circular motion, the power torque applied to the crank by the rider and collected by the bipolar linear Hall is a sine wave (y is larger than or equal to 0, and the period is pi), and each rotation angle of the crank can be calculated through logical calculation. The pedaling force is logically deduced through the detected crank rotation angle, and then the pedaling force at the rotation angle position with small effective force arm is compensated. The sensitivity of moment detection and the real-time of system response when improving the people and having an effect suddenly make power, make the moped can in time provide the helping hand according to cyclist's demand, improve the comfort level of riding.

The invention can effectively improve the man-machine synchronism and provide better riding experience for riders.

Scheme II: on the basis of the first scheme, the magnetic field generator further comprises a multi-pole magnetic ring and a double-Hall assembly; one of the multi-pole magnetic ring and the double Hall assembly is arranged on the middle shaft and rotates along with the middle shaft, and the other one is arranged in a static way relative to the middle shaft; the circuit board receives an electrical signal representing pedaling frequency from the double Hall assembly; the multi-pole magnetic ring comprises a plurality of N poles and S poles which are identical in shape and connected with each other to form a ring-shaped section; n poles and S poles in the multi-pole magnetic ring are alternately arranged; the double-Hall assembly comprises two unipolar switch Hall devices, and the two unipolar switch Hall devices can move relatively along the circumference of the multi-pole magnetic ring; two unipolar switches in the double-Hall assembly Hall one inducts N pole and the other inducts S pole.

The noun explains:

unipolar switching hall: the Hall element can only sense the N pole or the S pole, and a rectangular wave representing a high level or a low level can be formed when the N pole or the S pole is sensed; and logically deducing the pedaling frequency according to the number of rising edges of a potential diagram formed by the single-polarity switch Hall.

Pedaling frequency: refers to the frequency with which a cyclist pedals the pedals of the power-assisted bicycle.

Compared with the magnetic steel applied in the prior art, each magnetic pole in the multi-pole magnetic ring is continuously connected, each magnetic pole in the multi-pole magnetic ring is connected into a whole, the installation is convenient, the magnetic poles are more accurately and sensitively sensed by the switch Hall, the pedaling frequency detected by the double Hall assembly is more accurate, the pedaling frequency is a necessary parameter for calculating the torque, the logically calculated torque is more accurate, the relative motion of the multi-pole magnetic ring and the double Hall assembly is synchronous with the rotation of the center shaft, and the power-assisted bicycle can accurately reflect the rotation condition of the center shaft and accurately provide power assistance.

The third scheme is as follows: on the basis of the second scheme, the device further comprises a deformation bridge arranged on the middle shaft, wherein a strain gauge unit is arranged on the deformation bridge; the circuit board receives an electric signal representing the magnitude of the torque moment from the strain gauge unit.

One of the multi-pole magnetic ring and the double Hall assemblies synchronously generates relative movement with the rotation of the middle shaft, an electric signal representing the pedaling frequency is detected through the multi-pole magnetic ring and the double Hall assemblies (namely the electric signal representing the pedaling frequency can be directly detected, and the electric signal capable of logically deducing the pedaling frequency can also be detected, wherein the specific situation is not repeated according to the specific model selection of the switch Hall, and the electric signal is transmitted to the circuit board, and the pedaling frequency is deduced through logical calculation by the circuit board. The deformation bridge transmits the torque force applied to the middle shaft to the strain gauge unit through deformation, the strain gauge unit transmits an electric signal representing the torque force to the circuit board, and the circuit board deduces the torque force through logic calculation. The pedaling frequency and the torque moment are key parameters for calculating the output power applied to the power-assisted bicycle by a rider, and the two parameter values are accurately detected, so that the manpower output power can be accurately calculated, the theoretical output power required to be output by the power-assisted bicycle is further accurately calculated, and the power-assisted bicycle provides accurate power assistance for the power-assisted bicycle according to the power.

And the scheme is as follows: on the basis of the third scheme, a torque acquisition circuit and a torque processing control circuit are arranged on the circuit board; the torque acquisition circuit is used for receiving an electric signal representing the magnitude of the torque from the strain gauge unit; the torque processing control circuit receives the electric signal representing the magnitude of the torque from the torque acquisition circuit and logically calculates the magnitude of the torque, the torque processing control circuit receives the electric signal representing the pedaling frequency from the double Hall assembly and logically calculates the pedaling frequency, and the torque processing control circuit receives the electric signal representing the crank rotation angle from the bipolar linear Hall assembly and logically calculates the crank rotation angle.

The double Hall assembly and the bipolar linear Hall are connected in the torque processing control circuit, and the torque acquisition circuit only acquires signals from the strain gauge unit. The theoretical output power of the motor for controlling the rotation of the motor can be conveniently calculated through the detected torque moment and the pedaling frequency, so that the assistance provided by the power-assisted bicycle can meet the actual requirements of a rider.

And a fifth scheme: on the basis of the third scheme, a torque acquisition circuit and a torque processing control circuit are arranged on the circuit board; the torque acquisition circuit is used for receiving an electric signal representing the magnitude of torque from the strain gauge unit, receiving an electric signal representing pedaling frequency from the double-Hall assembly, and receiving an electric signal representing the rotation angle of the crank from the bipolar linear Hall; and the torque processing control circuit is used for receiving electric signals respectively representing the magnitude of the torque, the pedaling frequency and the crank rotation angle from the torque acquisition circuit and logically calculating the magnitude of the torque, the pedaling frequency and the crank rotation angle.

The double-Hall assembly, the bipolar linear Hall and the strain gauge unit are all connected in a torque acquisition circuit, the torque acquisition circuit acquires the torque moment, the pedaling frequency and the crank rotation angle at the same time, and the torque processing control circuit is used for calculating the theoretical output power of the motor according to the torque moment and the pedaling frequency and compensating for the pedaling force according to the crank rotation angle.

Scheme six: on the basis of the third scheme, a torque acquisition circuit and a torque processing control circuit are arranged on the circuit board; the torque acquisition circuit is used for receiving an electric signal representing the magnitude of the torque from the strain gauge unit and receiving an electric signal representing the pedaling frequency from the double-Hall assembly; the torque processing control circuit is used for receiving an electric signal representing the crank rotation angle from the bipolar linear Hall and logically calculating the crank rotation angle; and the torque processing control circuit is used for receiving the electric signals respectively representing the magnitude of the torque and the pedaling frequency from the torque acquisition circuit and logically calculating the magnitude of the torque and the pedaling frequency.

The strain gauge unit and the double-Hall assembly are connected in the torque acquisition circuit, and the bipolar linear Hall assembly is connected in the torque processing control circuit.

The scheme is seven: on the basis of the third scheme, a torque acquisition circuit and a torque processing control circuit are arranged on the circuit board; the torque acquisition circuit is used for receiving an electric signal representing the magnitude of the torque from the strain gauge unit and receiving an electric signal representing the rotation angle of the crank from the bipolar linear Hall; the moment processing control circuit is used for receiving an electric signal representing the pedaling frequency from the double Hall assembly and logically calculating the pedaling frequency; and the torque processing control circuit is used for receiving the electric signals respectively representing the magnitude of the torque and the crank rotation angle from the torque acquisition circuit and logically calculating the magnitude of the torque and the crank rotation angle.

The strain gauge unit and the bipolar linear Hall are connected in the torque acquisition circuit, and the double Hall assembly is connected in the torque processing control circuit.

And the eighth scheme is as follows: on the basis of any one of the schemes four to seven, the torque processing control circuit calculates the theoretical output power of the motor according to the torque force and the pedaling frequency logic and sends the theoretical output power to the motor controller for controlling the motor to rotate.

Through the theoretical output power of the motor, the motor controller can control the motor to rotate according to the actual demand condition of a rider, and accurate power assistance is provided for the power-assisted bicycle.

The scheme is nine: on the basis of the eighth scheme, the torque processing control circuit calculates the pedaling force according to the crank rotation angle logic and sends an acceleration signal to the motor controller according to the pedaling force, and the motor controller adjusts the speed of the motor reaching the theoretical output power of the motor.

The pedaling force applied to the power-assisted bicycle by the legs of the cyclist is restored through the crank rotation angle, so that the response delay caused by the fluctuation of the force arm is avoided, the cyclist can respond timely when the pedaling force is increased on any crank rotation angle position, and the riding experience of the cyclist is improved.

And a scheme ten: on the basis of any one of the fourth to seventh schemes, the torque processing control circuit calculates the pedaling force according to the crank rotation angle logic and corrects the torque according to the pedaling force to form a composite torque, and the torque processing control circuit calculates the composite output power of the motor according to the composite torque and the pedaling frequency logic and sends the composite output power to the motor controller for controlling the motor to rotate.

The pedaling force applied to the power-assisted bicycle by the legs of the cyclist is restored through the crank rotation angle, and then the pedaling force is corrected to correct the torque to form a synthesized torque, so that the power error caused by the fluctuation of the force arm when the crank is transmitted to the middle shaft is avoided, the assistance provided by the motor can be timely adjusted when the pedaling force is changed on any crank rotation angle position by the cyclist, and the riding experience of the cyclist is improved.

Drawings

Fig. 1 is a schematic structural diagram of an axial torque detection system 1 according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a deformation bridge in embodiment 1 of the axial torque detection system according to the present invention.

Fig. 3 is a logic block diagram of an embodiment 1 of the axle torque detection system of the present invention.

Fig. 4 is a schematic structural diagram of a multi-pole magnetic ring in embodiment 1 of the axial torque detection system of the present invention.

Fig. 5 is a schematic structural diagram of a two-pole magnetic ring in embodiment 1 of the axial torque detection system of the present invention.

Fig. 6 is a logic block diagram of embodiment 2 of the axle torque detection system of the present invention.

Fig. 7 is a logic block diagram of embodiment 3 of the axle torque detection system of the present invention.

Fig. 8 is a logic block diagram of embodiment 4 of the axle torque detection system of the present invention.

Fig. 9 is a schematic structural diagram of an axial torque detection system in accordance with embodiment 5 of the present invention.

Fig. 10 is a schematic structural diagram of a multi-pole magnetic ring in an embodiment 5 of the axial torque detection system according to the present invention.

Fig. 11 is a schematic structural view of a two-pole magnetic ring in embodiment 5 of the axial torque detection system according to the present invention.

Detailed Description

The following is further detailed by the specific embodiments:

reference numerals in the drawings of the specification include: the device comprises a middle shaft 1, a locking nut 2, a clamping jaw 3, a right bowl group 4, a first clamp spring 5, a deformation bridge 6, a first bearing 7, a dustproof sleeve 8, an installation sleeve 9, a magnetism isolating sleeve 10, a multi-pole magnetic ring 11, a strain gauge 12, a circuit board 13, a first magnetism isolating sheet 14, a wireless power supply receiving coil 15, a second magnetism isolating sheet 16, a wireless power supply transmitting coil 17, a second bearing 18, a third bearing 19, a second clamp spring 20, a fourth bearing 21, a left bowl group 22, a first switch Hall 23, a second switch Hall 24, a two-pole magnetic ring 25 and a bipolar linear Hall 26.

Example 1:

example 1 is substantially as shown in figure 1: the middle shaft 1 torque detection system comprises a locking nut 2, a clamping jaw 3, a left bowl group 22, a right bowl group 4, a middle shaft 1, a deformation bridge 6, a sleeve and a magnetism isolating sleeve 10.

As shown in the figure 1, the left end and the right end of the middle shaft 1 are respectively connected with a left crank of a left pedal and a right crank of a right pedal through fastening screws, the left crank is positioned on the left side of the left bowl group 22, and the right crank is positioned on the right side of the right bowl group 4. The outer side surface of the middle shaft 1 is provided with an external thread at the position connected with the deformation bridge 6. The deformation bridge 6 is sleeved on the middle shaft 1, the deformation bridge 6 is connected with the middle shaft 1 through reverse threads, and the threaded part of the middle shaft 1 is locked with the internal threads of the deformation bridge 6. The deformation bridge 6 is connected with the middle shaft 1 through a reverse threaded structure, replaces the original tooth-shaped structure buckling, guarantees the zero-clearance connection between the middle shaft 1 and the deformation sleeve, avoids the shake of the tooth-shaped butt joint in the positive and negative rotation process, guarantees the accuracy of data acquisition, and is convenient to install.

The left bowl group 22 and the right bowl group 4 are respectively installed at the left end and the right end of the center shaft 1, the left bowl group 22 and the right bowl group 4 are respectively provided with external threads, the two ends of a five-way pipe of the moped frame are provided with internal threads corresponding to the left bowl group 4 and the right bowl group 4, and the center shaft 1 is installed in the five-way pipe through the left bowl group 22 and the right bowl group 4. The left bowl group 22 and the right bowl group 4 connect the middle shaft 1 and the frame of the power-assisted bicycle into a whole, and meanwhile, the left bowl group 22 and the right bowl group 4 play a limiting and fixing role in all structures connected to the middle shaft 1. The left bowl group 22 is fixed on the middle shaft 1 through a fourth bearing 21, the right bowl group 4 is fixed on the middle shaft 1 through a first bearing 7, wherein an inner ring of the fourth bearing 21 is in contact with the middle shaft 1, and an inner ring of the first bearing 7 is in contact with the deformation bridge 6 to press the deformation bridge 6 on the middle shaft 1. The first jump ring 5 that radially inwards stretches out is installed to the inboard of right bowl group 4, and is spacing to first bearing 7 through first jump ring 5. The left end face of the first clamp spring 5 is abutted against the right end face of the first bearing 7.

The sleeve comprises a magnetism isolating sleeve 10, a mounting sleeve 9 and a dustproof sleeve 8 which are sleeved on the middle shaft 1 from inside to outside and used for fixing the middle shaft 1 or providing a connecting structure for other devices on the middle shaft 1. A first magnetism isolating piece 14 and a second magnetism isolating piece 16 which surround the middle shaft 1 from inside to outside are arranged between the magnetism isolating sleeve 10 and the dustproof sleeve 8. The first magnetism isolating sheet 14 close to the middle shaft 1 has lower magnetic permeability, prevents a circuit between the first magnetism isolating sheet 14 and the second magnetism isolating sheet 16 from transmitting electromagnetic signals to the middle shaft 1, and reduces the influence of the middle shaft 1 on the circuit arranged on the middle shaft 1. The second magnetism isolating sheet 16 far away from the central shaft 1 has high magnetic permeability, and guides the circuit between the first magnetism isolating sheet 14 and the second magnetism isolating sheet 16 to send an electromagnetic signal towards the direction of the second magnetism isolating sheet 16, so that the external divergence of a magnetic field can be ensured, and the circuit arranged on the central shaft 1 can better transmit the signal.

The magnetism isolating sleeve 10 is directly sleeved on the middle shaft 1, the longitudinal section of the contact part of the middle shaft 1 and the magnetism isolating sleeve 10 is in a ladder step structure, namely the contact surface of the middle shaft 1 and the magnetism isolating sleeve 10 is concave-convex, the shape of the inner side surface of the magnetism isolating sleeve 10 is matched with that of the outer side surface of the middle shaft 1, and therefore the magnetism isolating sleeve 10 can be directly sleeved on the middle shaft 1 without worrying about the fact that the magnetism isolating sleeve 10 slides left and right. The left end surface of the magnetism isolating sleeve 10 is abutted with the right end surface of the third bearing 19, and the right end surface of the magnetism isolating sleeve 10 is abutted with the circuit board 13 arranged on the middle shaft 1. In order to prevent the circuit board 13 from sliding on the middle shaft 1, an installation groove for installing the circuit board 13 is formed on the outer side surface of the middle shaft 1. The third bearing 19 is used for limiting the magnetism isolating sleeve 10, and the magnetism isolating sleeve 10 can be stably sleeved on the middle shaft 1 through the third bearing 19 and the circuit board 13 without sliding. And a second annular groove is formed in the outer side surface of the magnetic isolation sleeve 10, and the second annular groove is positioned right below the first annular groove. The second annular groove and the first annular groove are coaxial with the middle shaft 1. In the second annular groove, a first magnetism isolating sheet 14 and a wireless power supply receiving coil 15 are sleeved from inside to outside in sequence. The wireless power supply receiving coil 15 is connected to the circuit board 13 to supply power to the circuit board 13. The wireless power receiving coil 15 can rotate along with the central shaft 1.

Through the first annular groove and the second annular groove, the first magnetism isolating piece 14, the wireless power supply receiving coil 15, the wireless power supply transmitting coil 17 and the second magnetism isolating piece 16 are sequentially sleeved between the magnetism isolating sleeve 10 and the dustproof sleeve 8 from inside to outside, because the first annular groove and the second annular groove are coaxial and the second annular groove is positioned below the first annular groove, the wireless power supply receiving coil 15 and the wireless power supply transmitting coil 17 between the first magnetism isolating piece 14 and the second magnetism isolating piece 16 form a coaxial and parallel lantern ring structure, and the wireless power supply transmitting coil 17 surrounds the wireless power supply receiving coil 15. The wireless power supply transmitting coil 17 is connected with a drive circuit wire arranged on the frame of the moped. According to the Maxwell electromagnetic field theory, the driving circuit generates a changing electric field through the wireless power supply transmitting coil 17, the changing electric field can excite a changing magnetic field, and the changing electric field is generated at the wireless power supply receiving coil through resonance between the coils, so that the effect of energy transmission is achieved. Because the wireless power supply transmitting coil 17 and the wireless power supply receiving coil 15 are parallel, and have variable magnetic flux constantly, the coil can generate current no matter whether rotating or not, and the normal power supply of the central shaft 1 torque detection system is ensured.

Through the first magnetism isolating sheet 14, the resonant coil formed by the wireless power supply transmitting coil 17 and the wireless power supply receiving coil 15 is isolated from the middle shaft 1, the quality factor of the coil is improved, the loss of energy transfer is reduced, and the stability and the consistency of the product are improved. Through the second magnetism isolating sheet 16, equivalently, a layer of magnetism isolating material is wound outside the resonance coil, so that the energy of the resonance coil is prevented from radiating outwards, and the loss is reduced; the influence of the five-way pipes of the vehicle frames made of different materials on the product is reduced, the energy absorbed by the metal five-way pipes is reduced, the condition that the power consumption of the system is unstable is avoided, and the consistency of the product is ensured.

The longitudinal section of the right end of the dust-proof sleeve 8 is also in a ladder step structure, and the ladder step structure is a structure which is bent at a right angle like a ladder, namely, the right end of the dust-proof sleeve 8 is integrally formed and connected with a cylindrical structure with a reduced diameter. The inner side of the right bowl group 4 is contacted with the outer side surface of the right end of the dustproof sleeve 8, namely, the right bowl group 4 compresses the right end of the dustproof sleeve 8. The left end of the dustproof sleeve 8 is directly abutted with the end face of the left bowl group 22. The two ends of the dustproof sleeve 8 are respectively connected with the left bowl group 22 and the right bowl group 4 to form a unified whole which surrounds the middle shaft 1 in the circumferential direction, and the dustproof sleeve conveniently surrounds devices connected to the middle shaft 1 together with the left bowl group 22 and the right bowl group 4 so that the dustproof sleeve can be firmly connected to the middle shaft 1.

The left end of installation cover 9 and the longitudinal section of right-hand member all are ladder step structure, and the left end of installation cover 9 and right-hand member diameter all reduce, make the left end lateral surface of installation cover 9 contact with left bowl group 22 medial surface, and the right-hand member lateral surface of installation cover 9 contacts with the medial surface of dirt proof boot 8. A first annular groove is formed in the outer side surface of the mounting sleeve 9 and is close to the left bowl group 22, and a wireless power supply transmitting coil 17 and a second magnetism isolating sheet 16 are sequentially sleeved in the first annular groove from inside to outside. The left end inner side surface of the mounting sleeve 9 is sequentially connected with a second bearing 18 and a third bearing 19 from left to right, inner rings of the second bearing 18 and the third bearing 19 are in contact with the middle shaft 1, the mounting sleeve 9 is firmly sleeved on the middle shaft 1 through the two bearings of the second bearing 18 and the third bearing 19, meanwhile, the mounting sleeve 9 can move relative to the middle shaft 1 through the second bearing 18 and the third bearing 19, when the middle shaft 1 rotates, the mounting sleeve 9 can keep static, a wireless power supply transmitting coil 17 arranged in a first annular groove can be statically arranged on a moped frame and connected with a driving circuit, and the driving circuit is connected with a power supply arranged at the frame and the like.

The lateral surface that axis 1 and left bowl group 22 are connected is gone up to open and is had the recess, has second jump ring 20 through the recess joint, and second jump ring 20 is located between fourth bearing 21 and the second bearing 18, and the left end face of fourth bearing 21 and the right-hand member face butt of second jump ring 20, the right-hand member face butt of second bearing 18 and the left end face butt of second jump ring 20, and second jump ring 20 has played the effect of spacing left bowl group 22 and installation cover 9 simultaneously. The second circlip 20 can also be directly clamped with the inner rings of the second bearing 18 and the third bearing 19, so that the inner rings of the second bearing 18 and the third bearing 19 are prevented from moving relative to the middle shaft 1.

In the embodiment, a circuit board 13 in the installation groove of the middle shaft 1 is provided with a double Hall assembly, a mounting sleeve 9 outside the installation groove is provided with a multi-pole magnetic ring 11 which is opposite to the double Hall assembly, and the multi-pole magnetic ring 11 is coaxial with the middle shaft 1. Two switches of the double-Hall assembly are in Hall facing to the multi-pole magnetic ring 11. The circuit board 13 in the mounting groove of the middle shaft 1 is provided with a bipolar linear Hall 26, the mounting sleeve 9 outside the mounting groove is provided with a two-pole magnetic ring 25 which is opposite to the bipolar linear Hall 26, and the two-pole magnetic ring 25 is coaxial with the middle shaft 1.

The circuit board 13 installed in the mounting groove is a torque signal acquisition and processing board, and the torque signal acquisition and processing board cannot slide on the middle shaft 1 through the mounting groove.

As shown in fig. 3, the torque signal acquisition processing board in this embodiment is mounted with a torque acquisition circuit and a torque processing control circuit. The moment acquisition circuit and the moment processing control circuit are both arranged on the middle shaft 1 and rotate along with the middle shaft 1. The wireless power supply receiving coil 15 which is also arranged on the middle shaft 1 supplies power to the whole moment signal acquisition and processing board through electromagnetic induction with the wireless power supply transmitting coil 17.

The moment acquisition circuit comprises a strain gauge 12 Wheatstone full bridge consisting of strain gauges 12 units, a first operational amplifier unit connected with the strain gauge 12 Wheatstone full bridge, a first microcontroller connected with the first operational amplifier unit, and a first transmitting module connected with the first microcontroller and used for transmitting an electric signal to the moment processing control circuit.

The moment processing control circuit comprises a first receiving module connected with the first transmitting module, a second microcontroller connected with the first receiving module, a current detector, a double Hall assembly and a bipolar linear Hall 26 which are respectively connected with the second microcontroller, and a second transmitting module connected with the second microcontroller.

The double-Hall assembly comprises two unipolar switch Hall devices used for detecting pedaling frequency and the rotation direction of the middle shaft 1, the two switch Hall devices are respectively a first switch Hall device 23 and a second switch Hall device 24, the first switch Hall device 23 senses an N pole, the second switch Hall device 24 senses an S pole, the first switch Hall device 23 senses the N pole, other switch Hall devices are low levels, and when the first switch Hall device 23 rotates relative to the multi-pole magnetic ring 11, the first switch Hall device 23 forms a rectangular wave indicating regular change of the high and low levels. Similarly, the second switch hall 24 is at a high level when sensing the S pole, and the others are at a low level, and when the second switch hall 24 rotates relative to the multi-pole magnetic ring 11, the second switch hall 24 forms a rectangular wave indicating regular changes of the high and low levels. According to the number of rising edges of a potential diagram formed by the two unipolar switches and the Hall, the pedaling frequency can be logically deduced. Because the first switch hall 23 and the second switch hall 24 are arranged side by side, and the magnetic poles sensed by the two switch hall are different, the steering of the middle shaft 1 can be logically deduced through the relative position of the rising edges of the potential diagrams formed by the two switch hall respectively. By adopting the prior art, when the middle shaft 1 rotates forwards, the power supply on the power-assisted bicycle supplies power, and when the middle shaft 1 rotates backwards, the power supply on the power-assisted bicycle is powered off, so that adverse effects on a motor and the like caused by the reverse rotation of the middle shaft 1 are avoided.

The bipolar linear hall 26 can sense both an N pole and an S pole, and continuously represents voltages generated by induction as the induction magnetic poles are different and the magnetic pole positions of the bipolar linear hall 26 relative to two magnetic rings are different, and when the S pole and the N pole are semicircular and equal in length, the voltage change curve sensed by the bipolar linear hall 26 is a sine curve or a cosine curve. By utilizing the logic calculation of sine or cosine curves, the corresponding rotation angle of the crank on each voltage value and the corresponding pedaling force magnitude of each crank rotation angle can be calculated, and then the pedaling force on the rotation angle position with small arm of force and incapable of accurately reflecting the pedaling force change can be compensated.

The torque processing control circuit calculates the pedaling force according to the crank rotation angle logic and sends an acceleration signal to the motor controller according to the pedaling force, and the motor controller adjusts the speed of the motor reaching the theoretical output power of the motor. The pedaling force applied to the power-assisted bicycle by the legs of the cyclist is restored through the crank rotation angle, so that the response delay caused by the fluctuation of the force arm is avoided, the cyclist can respond timely when the pedaling force is increased on any crank rotation angle position, and the riding experience of the cyclist is improved.

In this embodiment, both the first microcontroller and the second microcontroller may be a universal-type single chip microcomputer.

Among the moment acquisition circuit, through 12 Wheatstone full bridges of foil gage 12 with the axis 1 that foil gage 12 detected rotate the torsion moment size that produces change into the deformation of foil gage 12 and then change into the resistance change of 12 Wheatstone full bridges of foil gage, will be because the voltage signal transmission that resistance change and synchronous change for first fortune unit of putting, pass through first fortune unit with the voltage change signal transmission after enlargiing for the first microcontroller who is regarded as moment acquisition module, first microcontroller sends this voltage change signal of representation torsion moment size for moment processing control circuit through first transmitting module and first receiving module. The second microcontroller serving as a torque processing module in the torque processing control circuit acquires voltage signals representing the magnitude of torque from the torque acquisition circuit through the first receiving module, and simultaneously acquires electric signals representing pedaling frequency and crank rotation angle through a double-Hall assembly and a bipolar linear Hall 26 connected with the second microcontroller, and the second microcontroller calculates the pedaling frequency according to the prior art logic. The second microcontroller calculates the torque according to the electric signal logic representing the torque, multiplies the torque by the pedaling frequency to obtain the human power output power of the rider, and multiplies the human power output power by the assistant ratio to obtain the theoretical output power of the motor.

And the second microcontroller calculates the crank rotation angle according to the arcsine logic or the arccosine logic. The pedaling force at the rotation angle position is deduced by the second microcontroller according to the crank rotation angle logic, and the second microcontroller generates an acceleration signal according to the variation of the pedaling force and sends the acceleration signal to the motor controller, so that the motor controller adjusts the speed of the motor reaching the theoretical output power of the motor. The pedaling force applied to the power-assisted bicycle by the legs of the cyclist is restored through the crank rotation angle, so that the response delay caused by the fluctuation of the force arm is avoided, the cyclist can respond timely when the pedaling force is increased on any crank rotation angle position, and the riding experience of the cyclist is improved.

The second microcontroller sends the theoretical output power of the motor and the acceleration signal to the motor controller through the second transmitting module and the second receiving module, so that the motor controller controls the motor to rotate according to the theoretical output power of the motor, and the motor can accurately provide power assistance for the power-assisted bicycle according to the actual requirements of a rider. When the detected crank rotation angle is not in the pre-stored rotation angle range value, the moment actually reflects the force application condition of the rider on the power-assisted bicycle, so that the manpower output power is calculated by directly multiplying the moment by the pedaling frequency through logic.

Because the torque acquisition circuit and the torque processing control circuit in the embodiment are both arranged on the central shaft 1, the two circuits can be connected by adopting a wire, namely, the first transmitting module and the first receiving module are both mutually connected wires. And a second transmitting module and a second receiving module between the torque processing control circuit and the motor controller are in wireless communication, and the second transmitting module and the second receiving module can be a Bluetooth module, a radio frequency module or other wireless communication modules in wireless connection.

In addition, a speed sensor is connected with a second microcontroller in the torque processing control circuit, the running speed of the power-assisted bicycle is detected by utilizing the prior art, a plurality of power-assisted ratios pre-stored in the second microcontroller are automatically selected according to the running speed, each power-assisted ratio corresponds to one running speed range value, and the power-assisted ratio corresponding to the running speed is selected as a key parameter for calculating the theoretical output power of the current motor to participate in calculation by comparing the detected running speed with the running speed range value.

The current detector in the torque processing control circuit transmits a detected motor current signal to the second microcontroller, the second microcontroller compares actual current detected by the current detector with a theoretical current value calculated through motor theoretical output power logic, and the output power of the motor is increased or reduced, so that the motor can adjust the power assisting size of the motor according to the actual running condition of the power-assisted bicycle, the rider can apply force without effort, and power is saved.

In this embodiment, the wireless power supply receiving coil 15 generating current is separated from the torque signal acquisition processing board, so that the high-frequency signal received by the wireless power supply receiving coil 15 can be isolated from the low-frequency signal received by the torque signal acquisition processing board, and the interference on torque signal acquisition can be avoided. Install first antenna on the moment signal acquisition and processing board, install the second antenna on the dorsal axis 1 of moment signal acquisition and processing board, moment signal acquisition and processing board has been installed in one side of mounting groove promptly, first antenna has been installed on the moment signal acquisition and processing board, second antenna has been installed at the opposite side of mounting groove promptly at the back of first antenna promptly, two wireless communication antennas are located the relative both sides of axis 1 mounting groove respectively, connect into two for the wireless communication antenna wire and become along with axis 1 pivoted rotating antenna together, compensate present antenna back because sheltered from the shortcoming that can't transmit, make the rotating antenna who forms can carry out signal transmission three hundred sixty degrees all-roundly. Meanwhile, because of the two wireless communication antennas, the strength of antenna signal transmission is enhanced, especially when the middle shaft 1 rotates, one wireless communication antenna is always close to the other, and because the two antennas can radiate in a full range, the continuity and the signal strength of signal transmission are effectively improved, the data of the middle shaft 1 are not lost in the rotating process, the accuracy of data acquisition is ensured, and the sensitivity and the stability of the system are improved.

The wire connected between the first antenna and the second antenna is coiled on the central shaft 1 in a snake-shaped way to form a coil, so that the external normal communication of the central shaft 1 in the rotating process is ensured, no dead angle is generated, and meanwhile, the coil also plays a role in fixing the second antenna.

In this embodiment, the first antenna and the second antenna are two transmitting ends of the second transmitting module, and transmit the theoretical output power of the motor calculated by the torque processing control circuit to the motor controller.

In this embodiment, the current detector may directly adopt an operational amplifier circuit, and the current detector may directly perform AD acquisition through the operational amplifier circuit. The method is characterized in that a weak voltage signal is collected, amplified by an operational amplifier, and acquired by AD (analog-to-digital) and subjected to a filtering algorithm to obtain the current of the motor. The current detector can be regarded as a second operational amplifier unit, the second operational amplifier unit is the same as the first operational amplifier unit, and the current operational amplifier chip comprising the operational amplifier circuit can be directly adopted.

As shown in fig. 4, the multi-pole magnetic ring 11 in this embodiment has a total of forty-eight magnetic poles, i.e., twenty-four antipodes, one antipode including an N pole and an S pole. The whole multi-pole magnetic ring 11 is provided with one opposite pole and one opposite pole which are adjacent, namely the N pole and the S pole are arranged on the whole multi-pole magnetic ring 11 at intervals. When the two switch Hall devices rotate along with the central shaft 1, the two switch Hall devices can sense the constantly changing magnetic poles on the multi-pole magnetic ring 11. Because the N pole and the S pole are arranged at intervals, the pedaling frequency of the moped can be detected through the times of the N pole and the times of the S pole respectively sensed by the two switches. According to the characteristics of the two switches, the two switches are high level when N and S poles appear, the rest are low level, the detection track diagrams of the N pole and the S pole can be formed in real time, and the steering of the middle shaft 1 can be judged through the phase difference of the formed track diagrams. For example, when the central shaft 1 rotates clockwise, the rising edge of the first switch hall trace corresponds to the high level of the signal of the second switch hall, and the falling edge of the first switch hall corresponds to the low level of the signal of the second switch hall. When the middle shaft 1 rotates anticlockwise, the rising edge of the first switch Hall corresponds to the low level of the second switch Hall signal, and the falling edge of the first switch Hall corresponds to the high level of the second switch Hall signal. The prior art is used for detecting the pedaling frequency and generally adopts magnetic steels which are all discontinuous, the magnetic steels with different magnetic poles are required to be respectively installed, the operation is troublesome, and the process is complex. Because the multi-pole magnetic ring 11 is a whole, the installation is convenient, and each magnetic pole on the multi-pole magnetic ring 11 is fixed, the relative position can not be changed, so that the detection is more accurate, and compared with the prior art in which magnetic steel is used, the installation process is simplified and the detection sensitivity is improved when the multi-pole magnetic ring 11 is used; and the pedal frequency can be calculated by matching with the double Hall sensors, the rotation direction of the middle shaft 1 can be detected, the structure is simplified, and the cost is saved.

In order to enable the switch Hall to be detected more accurately, when the switch Hall is installed, two switch Hall pieces correspond to one antipole, when one switch Hall piece is aligned to the center of an N pole in the antipole, the other switch Hall piece is aligned to the junction of the N pole and an adjacent S pole, and therefore the following logic disorder caused by magnetizing fluctuation and Hall patch swing can be avoided to the maximum extent, because the N pole and the S pole are uniformly magnetized in theory but actually fluctuate, and errors can exist in the relative positions of the switch Hall pieces during batch patch mounting. Two switches hall are installed according to the previous method, and errors can be avoided to the maximum extent.

As shown in fig. 5, the two-pole magnetic ring 25 in this embodiment includes an S pole having a semicircular shape and an N pole having a semicircular shape, and the bipolar linear hall 26 is disposed in the two-pole magnetic ring 25. When the bipolar linear hall 26 rotates along with the central shaft 1, the bipolar linear hall 26 can induce the N pole and the S pole along the inner side surfaces of the two-pole magnetic ring 25, and because the N pole and the S pole are equal in length, a potential diagram formed by the induction poles of the bipolar linear hall 26 is a sine curve or a cosine curve. The rotation angle of the crank at each moment can be accurately calculated by calculating the slope of the curve, and then the torque is compensated at the positions where the moment arms approach to 0, so that when the positions are located, the middle shaft 1 torque detection system can sensitively and timely react to the torque change of a rider, and the assistance provided by the power-assisted bicycle can meet the actual requirement of the rider.

As shown in fig. 1 and 2, the left end of the deformation bridge 6 is connected with the middle shaft 1 through reverse threads; the right end of the deformation bridge 6 is connected with the clamping jaw 3 through a groove-shaped structure or a tooth-shaped structure, the right end of the clamping jaw 3 is provided with a locking nut 2 in threaded connection with the deformation bridge 6, and the clamping jaw 3 is tightly pressed with the deformation bridge 6 through the locking nut 2. The fluted disc of the power-assisted bicycle is fixed on the clamping jaw 3 through the locking nut.

Specifically, the deformation bridge 6 is a cylindrical structure which is coaxial with the middle shaft 1 and is sleeved outside the middle shaft 1, reverse internal threads are arranged at the left end of the deformation bridge 6, and the left end of the deformation bridge 6 is connected with the middle shaft 1 through a reverse thread structure. The right end of the deformation bridge 6 is suspended in the air and has a small gap with the center shaft 1, an outwardly convex tooth-shaped structure is arranged on the outer side surface of the right end of the deformation bridge 6, and the right end is connected with the fluted disc through the tooth-shaped structure, so that forces on the left side and the right side can be transmitted to the fluted disc through the deformation sleeve, and the bilateral moment effect is achieved.

Wherein, the deformation bridge 6 equally divides the deformation bridge 6 into N equal parts along the axial direction of the bottom bracket axle 1, and the deformation bridge 6 in each equal part has the same area of the outer surface area and the same volume. The same number and shape of strain gauges 12 are adhered to each equal part of the deformation bridge 6. Specifically, as shown in fig. 2, a strain gauge 12 is adhered to an outer ring of a connection portion between the deformation bridge 6 and the middle shaft 1, an included angle of 45 degrees is formed between a single strain gauge 12 and a projection direction of an axis of the middle shaft 1, and the two strain gauges 12 form a half bridge, that is, a half bridge is adhered to an outer surface of each equal portion of the deformation bridge 6. In this embodiment, the deformation bridge 6 is divided into two equal parts, and then a half bridge is pasted, and then a pair of strain gauges 12 are pasted at the position rotated by 180 degrees to form a half bridge, and two groups of half bridges form a full bridge; although the bonding direction and angle are common in the prior art, the number of the strain gauges 12 is reduced by optimizing the structure of the equivalent strain bridge 6 under the condition of ensuring the strength, unlike other existing strain bridges 6 in which the strain gauges 12 are bonded at each position, in this embodiment, only one set of strain gauges 12 needs to be bonded on the outer surface of each equivalent, which reduces the cost and ensures the acquisition precision. By adopting the deformation bridge 6 in the embodiment, after the stress transmitted by the strain gauge 12 is collected, the stress is firstly amplified, so that the detection sensitivity is improved; the influence of the uneven surface hardness or thickness of the deformation bridge 6 caused by heat treatment or machining on stress distribution is reduced, and the product consistency is improved.

In the embodiment, the strain gauges 12 are adhered to the outer ring of the connecting part of the deformation bridge 6 and the middle shaft 1, and a single strain gauge 12 forms a 45-degree angle with the axial direction to form a half bridge; then, a pair of strain gauges 12 is attached to the position rotated by 90 degrees to form half bridges according to the mode, two groups of half bridges form a full bridge, the full bridge is amplified by the first operational amplifier unit and then input into the first microcontroller, and the corresponding force is calculated; therefore, stress acquisition errors caused by uneven machining of the deformation bridge 6 can be avoided. Compare in prior art at 6 circumference of deformation bridge and paste the way of foil gage 12, the quantity of foil gage 12 has not only been reduced to this embodiment, and the cost is reduced, still through the circumference area of equal fractal deformation bridge 6, make all have a foil gage 12 to detect on being equallyd divide every position, and then can guarantee that there is foil gage 12 that detects on 6 all directions of deformation bridge, as long as it is appropriate to divide equally quantity, then can effectively guarantee the detection precision of deformation bridge 6 on reduce cost's basis.

When a rider tramples the left/right cranks, force is transmitted to the deformation bridge 6 through the middle shaft 1 and then transmitted to the clamping jaws 3 through the deformation bridge 6, and the clamping jaws 3 drive the fluted disc to rotate. The stress on the deformation bridge 6 is collected through the strain gauge 12, the strain gauge 12 converts the collected stress into an electric signal and transmits the electric signal to the first microcontroller through the first operational amplifier unit, the first microcontroller transmits the electric signal to the second microcontroller, the second microcontroller obtains the current force application size of a rider, namely the torque size through conversion, the torque moment is obtained through calculation by combining with the force arms stored in the second microcontroller at the rotation angle positions of the cranks in advance, the torque moment is multiplied by the pedaling frequency detected by the double Hall assembly and the coefficient value stored in the first microcontroller in advance, and the current manpower output power is obtained through calculation. The second microcontroller is pre-stored with a power-assisted ratio corresponding table, and the power-assisted ratio corresponding table comprises a plurality of groups of running speeds and power-assisted ratios which are arranged in a one-to-one correspondence manner. The current required assistance ratio can be determined through the driving speed detected by the speed sensor, the moment processing control circuit calculates theoretical output power which is required to be provided by the motor according to the assistance ratio and the output power of the current person, the theoretical current value of the motor is further calculated, and the motor controller controls the rotating speed of the motor according to the theoretical output power so as to control the assistance provided by the motor. The rotating speed of the motor is adjusted in real time by comparing the actual current and the theoretical current value of the motor detected by the current detector.

Meanwhile, the rotation angle of the crank at each moment is calculated through the logics of the two-pole magnetic ring 25 and the bipolar linear Hall 26, the pedaling force at each rotation angle of the crank can be calculated through the rotation angle from formula logics preset in the second microcontroller, and the pedaling force is compensated through a compensation method stored in the second microcontroller in advance to form an acceleration signal, so that the motor controller can accelerate according to the acceleration. The specific compensation method can be to proportionally increase or decrease the rotation speed of the motor, or other logic calculation to control the rotation speed of the motor. Through the two-pole magnetic ring 25 and the bipolar linear Hall 26, the situation that the moment signal acquired because the compensation arm of force does circular motion is different from the actual force applied by a person can be avoided, the man-machine synchronism is improved, and the problems that the person suddenly applies force at the place with the minimum arm of force, the sensor response is slow or no response is caused are avoided.

Each boosting ratio obtained according to the current running speed is a fixed value, and the specific value is set according to the corresponding standard. The power that the people needed different when riding on different road conditions, according to mark the helping hand ratio that the inside required, control the output power relation of people and motor, guarantee to ride the passerby and ride hard.

Most of the prior art schemes in the market can not accurately collect the torque, so that the torque cannot be accurately controlled, the output power of a person can not be accurately calculated, the motor can not provide reasonable assistance, and the rider can not have a very bad experience.

Compared with the scheme of only detecting the rotating speed in the prior art, the scheme of simultaneously detecting the rotating speed and the torque can be used for detecting the rotating speed and the torque, the torque control core is how to calculate the stable and accurate human tread power and the motor output power, the deformation bridge 6 is connected with the strain gauge 12 through equal parts in structural design to ensure that the force is uniformly and accurately acquired, the accuracy of calculating the motor power is ensured through a hardware circuit and software filtering, and the dynamic balance is achieved through real-time adjustment. When the motor rotates according to a certain motor theoretical output power under the control of the motor controller, a current detector arranged on the motor detects the current of the motor in the rotating process and feeds back the actual current value to the torque processing module. The second microcontroller in the torque processing module compares the actual current value with the theoretical current value, if the actual current value and the theoretical current value are different, the actual current value and the theoretical current value tend to be equal by adjusting the theoretical output power of the motor, the rotating speed of the motor is adjusted while the output power of the motor is adjusted, the power generated by the motor is adjusted, the whole torque detection, control and adjustment form a closed loop, and the adjustment of the power of the motor achieves dynamic balance. In brief, firstly, the output power of a person is calculated, the output power of the motor is detected through the current collector, and the output power of the motor is adjusted to be increased or decreased through comparison.

In the embodiment, the current feedback and the crank rotation position detection of the motor are introduced, so that the response time and the riding comfort are improved, and the rider can save more power while exerting no effort.

In the fixing of the sleeve, especially in the fixing of the mounting sleeve 9, the embodiment adopts the bearing to replace the traditional wear pad or the clamp spring, so that the whole middle shaft 1 almost has no friction force, and the energy consumed by overcoming the friction force of the middle shaft is effectively reduced. Specifically, an annular reinforcing rib is additionally arranged on the left side of the rotary sleeve, two bearings are respectively arranged at two ends of the reinforcing rib, a clamp spring is additionally arranged on the middle shaft 1 and is tightly attached to the bearing at the leftmost end, and the rotary plastic cylinder and the middle shaft 1 are fixed together in this way. The wear-resistant pad replaces the original wear-resistant pad, changes sliding friction into rolling friction, prolongs the service life of a wear part, reduces frictional resistance, reduces loss in the force transmission process, improves detection precision and prolongs the service life of a product; the axial/radial swing of the bearing and the sleeve in the rotating process is reduced, the fluctuation of mutual inductance between the two resonance coils is reduced, the fluctuation of energy transmission is reduced, and the stability and consistency of products are improved.

In the field, when people fix the sleeve, the universal means and the inertia thinking are that one end of the sleeve is fixed by a bearing, and the other end of the sleeve limits the position of the sleeve by adding a clamp spring on the central shaft 1, however, friction is easily generated between the clamp spring and the sleeve, and the gap between the clamp spring and the sleeve is larger and larger after long-term use. In the embodiment, two bearings are additionally arranged on the same side of the mounting sleeve 9, namely the second bearing 18 and the third bearing 19 simultaneously clamp the mounting sleeve 9 and the magnetism isolating sleeve 10, the second clamp spring 20 is clamped between the fourth bearing 21 and the second bearing 18, and the second clamp spring 20 cannot be in contact with the outer ring of the second bearing 18, so that the resistance of mutual friction to the middle shaft 1 is reduced, and the service life of a product is prolonged. The second bearing 18 and the third bearing 19 can connect the mounting sleeve 9 with the middle shaft 1 more stably, and meanwhile, the third bearing 19 and the magnetism isolating sleeve 10 are abutted to well limit the magnetism isolating sleeve 10.

The deformation bridge 6 is connected with the middle shaft 1 through a reverse threaded structure, the original tooth-shaped structure buckling is replaced, the middle shaft 1 is guaranteed to be in gapless connection with the deformation bridge 6, shaking in the tooth-shaped butt joint forward and backward rotation process is avoided, accuracy of data acquisition is guaranteed, and installation is convenient.

The rotary multi-pole magnetic ring 11 replaces the existing magnetic steel structure, so that the installation process is simplified, and the detection sensitivity is improved; and the pedal frequency can be calculated by matching with the double Hall assemblies, the rotation direction of the middle shaft 1 can be detected, the structure is simplified, and the cost is saved.

The middle shaft 1 rotates all the time in the use process, the wireless power supply and wireless communication mode is adopted in the embodiment, the resonant coil is wound on the middle shaft 1, the magnetic isolation sheets are wound on the upper surface and the lower surface of the resonant coil and are level to or higher than the coil, and the coil is isolated from the middle shaft 1 and surrounding metal parts such as bearings through the magnetic isolation sheets, so that the wireless power supply energy loss is reduced.

In this embodiment, the multi-pole magnetic ring 11 and the double hall assemblies synchronously generate relative motion along with the rotation of the central shaft 1, so that two unipolar switches in the double hall assemblies can obtain a potential diagram generated by induction by sensing an S pole and an N pole, and the pedaling frequency is derived through the logic of the number of rising edges in the potential diagram. The torsion which enables the middle shaft 1 to rotate is transmitted to the strain gauge 12 unit through the deformation bridge 6, an electric signal which represents the torsion moment of the middle shaft 1 is detected by the strain gauge 12 unit and is transmitted to the circuit board 13, and the circuit board 13 is logically pushed to the torsion moment. And multiplying the detected torque by the force arm to obtain the torque. The force arm is detected by the prior art.

When the bicycle is ridden with the power-assisted bicycle, the manual output power P is K X N F, K is a constant, N is a torque moment, and F is pedaling frequency; the output power which is currently applied to the power-assisted bicycle by a cyclist is converted by utilizing the product of the pedaling frequency and the torque, the theoretical output power of the motor can be calculated by multiplying the assistance ratio by the manpower output power, and the motor is controlled to rotate according to the theoretical output power of the motor to provide assistance for the power-assisted bicycle.

When a rider pedals the pedals, the crank moves circularly to form a power torque applied to the crank by the rider, and the crank drives the middle shaft to rotate in the rotating process to form a torque of the middle shaft. However, when the crank is rotated to some rotation angles, the effective arm of force is very small, so that the pedaling force of a rider pedaling cannot be fully used for forming power torque, and if the rider suddenly increases great torque at the rotation angle positions, the collected torque signal is still very small, and the real force application requirement of the rider cannot be reflected through the torque. The change of the power moment is very small, so that the torque moment of the middle shaft can not accurately and timely respond, and the riding experience of a rider is not good. However, the existing bottom bracket moment detection system does not take any effective measures against the problem. Through the two-pole magnetic ring and the bipolar linear Hall 26, the two devices synchronously generate relative motion along with the rotation of the middle shaft 1, so that the bipolar linear Hall 26 can form an electric signal for representing the rotation angle of the crank through detecting the N pole and the S pole on the two-pole magnetic ring, the electric signal is sent to the circuit board 13, and the circuit board 13 deduces the current rotation angle of the crank through logic calculation. When a rider pedals a pedal, a crank does circular motion in the process of pedaling by a person, when the rider pedals the pedal with the same force, the collected torque signal is a sine wave (y is more than or equal to 0, the period of the part is pi), through the detection of the position of the crank, when the force arm is very small, the compensation is directly performed according to the recovered pedaling force, the sensitivity of the torque detection and the real-time performance of system response when the person suddenly applies force are improved, the power-assisted bicycle can provide power assistance in time according to the requirement of the rider, and the riding comfort level is improved. The existing torque sensor in the market does not have the functions, so that the force is suddenly applied at the place with the smallest force arm, and the response is slow.

The multi-pole magnetic ring 11 and the double Hall assemblies are skillfully arranged in the embodiment, so that the double Hall assemblies can detect the pedaling frequency, the torque is calculated through logic, and necessary parameters are detected for obtaining the torque of the middle shaft 1 and the output power of people. The invention skillfully arranges the two-pole magnetic ring 25 and the bipolar linear Hall 26, so that when the middle shaft 1 rotates due to torsion, the bipolar linear Hall 26 obtains a sine graph or a cosine graph of voltage change of the crank in the rotating process by sensing the magnetic pole change on the two-pole magnetic ring 25, and calculates the current included angle between the crank and the middle shaft 1 through logic. The calculated torque is combined, so that the included angle between the crank and the middle shaft 1 at the moment and the torque on the middle shaft 1 can be calculated according to the rotating position of the crank.

According to the power-assisted bicycle, the multi-pole magnetic ring and the double-Hall assembly, as well as the two-pole magnetic ring and the bipolar linear Hall assembly are skillfully arranged, so that the power-assisted bicycle can accurately provide power assistance according to the actual requirements of a rider, and the problem that the response system of the existing torque detection system is slow due to the rotation angle of the crank can be effectively avoided.

In the embodiment, the whole article connected to the middle shaft is connected through the bearing, and the sleeve and the middle shaft are fixed together in this way. The wear-resistant pad replaces the original wear-resistant pad, changes sliding friction into rolling friction, prolongs the service life of a wear part, reduces frictional resistance, reduces loss in the force transmission process, improves detection precision and prolongs the service life of a product; the shaft/radial swing of the bearing and the sleeve in the rotating process is reduced, the fluctuation of mutual inductance between the wireless power supply transmitting coil and the wireless power supply receiving coil is reduced, the fluctuation of energy transmission is reduced, and the stability and consistency of products are improved.

In the embodiment, the wireless power supply transmitting coil and the wireless power supply receiving coil can be isolated from other metal structures of the power-assisted bicycle, such as a frame, a bearing, a middle shaft and the like, through the magnetic isolation sleeve, so that the loss of electric energy generated by the coils can be avoided to the maximum extent.

Example 2:

as shown in fig. 6, the present embodiment is different from embodiment 1 in that the dual hall elements and the bipolar linear hall 26 are connected in a torque acquisition circuit, the first microcontroller obtains electrical signals representing the pedaling frequency and the rotation direction of the center shaft 1 from the dual hall elements, and the first microcontroller obtains electrical signals representing the crank rotation angle from the bipolar linear hall 26 and transmits the electrical signals to the torque processing control circuit. At the moment, the two circuits can be arranged on the middle shaft 1 together or can be arranged separately, the torque acquisition circuit is arranged on the middle shaft 1, and the torque processing control circuit is arranged on the mounting sleeve 9. When the torque acquisition circuit and the torque processing control circuit are separately arranged, the first transmitting module and the first receiving module are wireless transmission modules, and the first antenna and the second antenna are two transmitting ends of the first transmitting module.

Example 3:

as shown in fig. 7, the present embodiment is different from embodiment 1 in that the dual hall elements and the strain gauge 12 unit are connected in a torque acquisition circuit, the first microcontroller obtains electrical signals representing the pedaling frequency and the rotation direction of the central shaft 1 from the dual hall elements, the bipolar linear hall 26 is connected in a torque processing control circuit, and the second microcontroller obtains electrical signals representing the crank rotation angle from the bipolar linear hall 26. At the moment, the two circuits can be arranged on the middle shaft 1 together or can be arranged separately, the torque acquisition circuit is arranged on the middle shaft 1, and the torque processing control circuit is arranged on the mounting sleeve 9. When the torque acquisition circuit and the torque processing control circuit are separately arranged, the first transmitting module and the first receiving module are wireless transmission modules, and the first antenna and the second antenna are two transmitting ends of the first transmitting module.

Example 4:

as shown in fig. 8, the present embodiment is different from embodiment 1 in that the bipolar linear hall 26 and the strain gauge 12 unit are connected in a torque acquisition circuit, and the first microcontroller obtains an electric signal representing the crank angle from the bipolar linear hall 26. The double Hall components are connected in the torque processing control circuit, and the second microcontroller obtains electric signals representing the pedaling frequency and the rotation direction of the middle shaft 1 from the double Hall components. At the moment, the two circuits can be arranged on the middle shaft 1 together or can be arranged separately, the torque acquisition circuit is arranged on the middle shaft 1, and the torque processing control circuit is arranged on the mounting sleeve 9. When the torque acquisition circuit and the torque processing control circuit are separately arranged, the first transmitting module and the first receiving module are wireless transmission modules, and the first antenna and the second antenna are two transmitting ends of the first transmitting module.

Example 5:

as shown in fig. 9, 10 and 11, the present embodiment is different from embodiment 1 in that a torque acquisition circuit is disposed on the middle shaft 1, and a torque processing control circuit is disposed on the mounting sleeve 9.

A moment signal acquisition board, a multi-pole magnetic ring 11 and a two-pole magnetic ring 25 are arranged on a middle shaft 1, a moment acquisition circuit is arranged on the moment signal acquisition board, a first antenna is arranged on the moment signal acquisition board, a second antenna is arranged on one side of the middle shaft 1, which is opposite to the moment signal acquisition board, and the two wireless communication antennas are connected through a wire to form a rotary antenna. A torque signal processing board is arranged on the mounting sleeve 9, and a torque processing control circuit is arranged on the torque signal processing board. Meanwhile, an antenna receiving module used for receiving signals transmitted by the first antenna and the second antenna is installed on the torque signal processing board, and the antenna receiving module transmits the signals transmitted by the torque acquisition circuit to a second microcontroller serving as the torque processing module. Two switch Hall devices which are respectively a first switch Hall device 23 and a second switch Hall device 24 and are opposite to the multipole magnetic ring 11 are arranged on the torque signal processing board. The torque signal processing board is provided with a bipolar linear Hall 26 which is opposite to the two-pole magnetic ring 25. At this time, the double Hall assemblies are positioned outside the multi-pole magnetic ring 11, and the bipolar linear Hall assembly 26 is positioned outside the two-pole magnetic ring 25. The first antenna and the second antenna are two transmitting ends of the first transmitting module.

Example 6:

the difference with embodiment 1 lies in that both ends of the dust-proof cover 8 are ladder step structures, that is, the diameter of both ends of the dust-proof cover 8 is smaller than the diameter of the middle part, so that both ends of the dust-proof cover 8 are respectively connected with the left bowl group 22 and the right bowl group 4, and the device connected to the middle shaft 1 is conveniently enclosed together with the left bowl group 22 and the right bowl group 4, so that the device can be firmly connected to the middle shaft 1.

Example 7:

the difference from embodiment 1 is that the circuit board 13 mounted in the mounting groove includes a power supply board and a torque signal acquisition processing board that are separated from each other, and a torque acquisition circuit and a torque processing control circuit are mounted on the torque signal acquisition processing board. The power panel is electrically connected with the wireless power supply receiving coil 15, the power panel is electrically connected with the torque signal acquisition board, and the power panel supplies power for the torque signal acquisition processing board. The power panel and the torque signal acquisition board are sleeved in the mounting groove side by side. And a third isolation magnetic sheet for isolating interference is connected between the power panel and the torque signal acquisition processing panel. The power panel and the torque signal acquisition and processing panel are separated, so that high-frequency signals can be isolated, and the interference on signal acquisition is avoided.

Example 8:

the difference with embodiment 1 is that the second snap spring 20 is fixed with the inner ring of the second bearing 18, so that the second bearing 18 and the second snap spring 20 do not rotate relatively, the resistance force for hindering the rotation of the middle shaft 1 formed by mutual friction is reduced, and the overall service life of the product is prolonged.

Example 9:

the difference with embodiment 1 is that the second circlip 20 is fixed with the inner rings of the second bearing 18 and the fourth bearing 21 respectively, so that the inner rings of the second bearing 18 and the fourth bearing 21 cannot rotate relatively, the resistance which hinders the rotation of the middle shaft 1 due to mutual friction is avoided, and the overall service life of the product is prolonged.

Example 10:

the difference from embodiment 1 is that a rotation angle range value is preset in the second microcontroller, and the rotation angle range value is a rotation angle set corresponding to the positions with too small moment arm. When the rotation angle logically calculated by the second microcontroller is within the rotation angle range value, the second microcontroller logically calculates the torque according to the electric signal representing the torque. After the torque processing control circuit calculates the human power output power through the pedaling frequency and the torque force, the torque processing control circuit deduces the pedaling force applied to the crank by the leg according to the crank rotation angle logic, the human power output power is proportionally increased or reduced through the variation of the pedaling force, the corrected motor theoretical output power is calculated according to the assistant ratio logic, namely the motor synthesized output power is sent to the motor controller to control the motor to rotate, the pedaling force applied to the power-assisted bicycle by the leg of the bicycle is restored through the crank rotation angle, the torque force is corrected through the pedaling force to form the synthesized torque, the power error caused by the fluctuation of the force arm and transmitted to the middle shaft of the crank is avoided, and the power-assisted provided by the motor can be timely adjusted when the pedaling force is changed at any crank rotation angle position of the crank by a bicycle rider, the riding experience of the rider is improved.

The foregoing is merely an example of the present invention, and common general knowledge in the field of known specific structures and characteristics is not described herein in any greater extent than that known in the art at the filing date or prior to the priority date of the application, so that those skilled in the art can now appreciate that all of the above-described techniques in this field and have the ability to apply routine experimentation before this date can be combined with one or more of the present teachings to complete and implement the present invention, and that certain typical known structures or known methods do not pose any impediments to the implementation of the present invention by those skilled in the art. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims

1. The middle shaft torque detection system comprises a circuit board; the method is characterized in that: the magnetic circuit also comprises a bipolar magnetic ring and a bipolar linear Hall;

one of the two-pole magnetic ring and the bipolar linear Hall is arranged on the middle shaft and rotates along with the middle shaft, and the other one is arranged in a static way relative to the middle shaft; the two-pole magnetic ring comprises an N pole and an S pole which are same in shape and connected with each other to form a ring-shaped section; the bipolar linear Hall device can move relatively along the circumferences of the two polar magnetic rings; the circuit board receives an electric signal representing the rotation angle of the crank from the bipolar linear Hall;

the device also comprises a multi-pole magnetic ring and a double-Hall assembly; one of the multi-pole magnetic ring and the double Hall assembly is arranged on the middle shaft and rotates along with the middle shaft, and the other one is arranged in a static way relative to the middle shaft; the circuit board receives an electrical signal representing pedaling frequency from the double Hall assembly; the multi-pole magnetic ring comprises a plurality of N poles and S poles which are identical in shape and connected with each other to form a ring-shaped section; n poles and S poles in the multi-pole magnetic ring are alternately arranged; the double-Hall assembly comprises two unipolar switch Hall devices, and the two unipolar switch Hall devices can move relatively along the circumference of the multi-pole magnetic ring; one of two unipolar switches in the double-Hall assembly senses an N pole and the other senses an S pole;

the strain gauge is characterized by further comprising a deformation bridge arranged on the middle shaft, wherein a strain gauge unit is arranged on the deformation bridge; the circuit board receives an electric signal representing the magnitude of the torque moment from the strain gauge unit;

the circuit board is provided with a torque acquisition circuit and a torque processing control circuit;

the torque processing control circuit calculates the theoretical output power of the motor according to the torque and the pedaling frequency logic and sends the theoretical output power to the motor controller for controlling the motor to rotate;

or the torque processing control circuit calculates the pedaling force according to the crank rotation angle logic and corrects the torque moment according to the pedaling force to form a composite torque, and the torque processing control circuit calculates the composite output power of the motor according to the composite torque and the pedaling frequency logic and sends the composite output power to the motor controller for controlling the motor to rotate.

2. The bottom bracket axle torque sensing system of claim 1, wherein: the torque acquisition circuit is used for receiving an electric signal representing the magnitude of the torque from the strain gauge unit; the torque processing control circuit receives the electric signal representing the magnitude of the torque from the torque acquisition circuit and logically calculates the magnitude of the torque, the torque processing control circuit receives the electric signal representing the pedaling frequency from the double Hall assembly and logically calculates the pedaling frequency, and the torque processing control circuit receives the electric signal representing the crank rotation angle from the bipolar linear Hall assembly and logically calculates the crank rotation angle.

3. The bottom bracket axle torque sensing system of claim 1, wherein: the torque acquisition circuit is used for receiving an electric signal representing the magnitude of torque from the strain gauge unit, receiving an electric signal representing pedaling frequency from the double-Hall assembly, and receiving an electric signal representing the rotation angle of the crank from the bipolar linear Hall; and the torque processing control circuit is used for receiving electric signals respectively representing the magnitude of the torque, the pedaling frequency and the crank rotation angle from the torque acquisition circuit and logically calculating the magnitude of the torque, the pedaling frequency and the crank rotation angle.

4. The bottom bracket axle torque sensing system of claim 1, wherein: the torque acquisition circuit is used for receiving an electric signal representing the magnitude of the torque from the strain gauge unit and receiving an electric signal representing the pedaling frequency from the double-Hall assembly; the torque processing control circuit is used for receiving an electric signal representing the crank rotation angle from the bipolar linear Hall and logically calculating the crank rotation angle; and the torque processing control circuit is used for receiving the electric signals respectively representing the magnitude of the torque and the pedaling frequency from the torque acquisition circuit and logically calculating the magnitude of the torque and the pedaling frequency.

5. The bottom bracket axle torque sensing system of claim 1, wherein: the torque acquisition circuit is used for receiving an electric signal representing the magnitude of the torque from the strain gauge unit and receiving an electric signal representing the rotation angle of the crank from the bipolar linear Hall; the moment processing control circuit is used for receiving an electric signal representing the pedaling frequency from the double Hall assembly and logically calculating the pedaling frequency; and the torque processing control circuit is used for receiving the electric signals respectively representing the magnitude of the torque and the crank rotation angle from the torque acquisition circuit and logically calculating the magnitude of the torque and the crank rotation angle.

6. The bottom bracket axle torque sensing system of claim 1, wherein: the torque processing control circuit calculates the pedaling force according to the crank rotation angle logic and sends an acceleration signal to the motor controller according to the pedaling force, and the motor controller adjusts the speed of the motor reaching the theoretical output power of the motor.