CN107628185B

CN107628185B - Torque force detector

Info

Publication number: CN107628185B
Application number: CN201610563442.6A
Authority: CN
Inventors: 梁嘉生
Original assignee: Xingan Electrical And Mechanical Co Ltd
Current assignee: Xingan Electrical And Mechanical Co Ltd
Priority date: 2016-07-18
Filing date: 2016-07-18
Publication date: 2019-12-06
Anticipated expiration: 2036-07-18
Also published as: CN107628185A

Abstract

The invention provides a torsion force detector, which comprises a torsion force transmission mechanism part with magnetic expansion and contraction characteristics, wherein the torsion force transmission mechanism part is arranged on an outer layer to form a shell-shaped sleeve, spiral threads which are engraved and penetrated through the sleeve are engraved on the sleeve to form a transmission part which is connected by a pair of spiral ribs with opposite rotation directions, a pair of magnetic conductive winding shafts are arranged in the transmission part and are surrounded by the transmission part, and a pair of exciting coils and a pair of measuring coils are wound on the magnetic conductive winding shafts. When the exciting coil is energized with alternating current, magnetic lines of force generated by excitation are intensively guided to pass through the spiral rib, so that the magnetic stretching effect of the torsion transmission member under torsion load can be more effectively expressed, and a voltage signal is induced in the measuring coil to achieve the effect of detecting torsion.

Description

Torque force detector

Technical Field

The present invention relates to a torque detector, and more particularly, to a magnetic telescopic torque detector for transmitting torque from a sleeve located at the periphery of the torque detector.

Background

The method of detecting the torque applied to the fixed shaft or the rotating shaft by using the magnetic expansion and contraction characteristics of the magnetic conductive material is widely used, and the method detects the change of the magnetic permeability of the fixed shaft or the rotating shaft when the torque is applied to the fixed shaft or the rotating shaft, and can calculate the magnitude of the torque applied to the shaft. The magnetic telescopic torque detection is a non-contact torque detection, and has the advantages of no abrasion, no need of maintenance, high reliability and the like compared with other torque detection methods.

The phenomenon of magnetic expansion and contraction characteristic is that when a specific material is subjected to tensile force or pressure, the magnetic permeability of the material changes correspondingly, if the magnetic permeability increases with the increase of the tensile force or decreases with the increase of the pressure, the material is called to have positive magnetic expansion and contraction characteristic, otherwise, the material is called to have negative magnetic expansion and contraction characteristic. When a torque force is applied to a shaft, the shaft will produce a pulling force and a pressure force at the angle of plus and minus 45 degrees respectively, so as to produce a phenomenon of magnetic permeability increase or decrease, and at least one set of coils is respectively arranged in the direction of plus and minus 45 degrees of the shaft by utilizing the phenomenon, or a spiral groove (or rib) with a specific length of plus and minus 45 degrees is respectively processed at the adjacent position on the shaft, and at least one set of coils is arranged at the periphery of the corresponding position as a detector, so that the inductance value of the set of coils can be correspondingly changed due to the change of the magnetic permeability, and when an alternating current power supply is applied to the coils, the corresponding torque force value can be detected by utilizing a proper circuit configuration. These basic applications can be found in U.S. patent nos. 4506554, 4697459, 4765192, 4823620, and the like.

The structure of the traditional magnetic telescopic torque force detector basically comprises that an upper transmission shaft is positioned at the center, a detection coil surrounds the outside, and a cylindrical magnetic conduction ring is used as an outer ring to increase the detection sensitivity. This arrangement is also applicable to motor-assisted bicycles, such as U.S. Pat. No. 8807260 and taiwan patent No. 293508, except that the applications are installed in a bottom break shell of a bicycle, and the torque generated when the pedal crank shaft is acted by the pedal force is detected, and the torque signal is converted into a digital signal and transmitted to a control unit as a judgment basis for controlling the operation timing of a motor providing the assistance force. However, this configuration requires changing the shape and assembly interface of the original frame, and is still inconvenient in application.

Disclosure of Invention

Accordingly, the present invention is directed to a torque detector for a bicycle, which is adapted to detect the pedaling force applied to the pedals by the rider. The power input and power output of the bicycle are respectively a pedal and a rear tire, and a pedal force detector can be arranged between the pedal and the rear tire, or a torque force detector is arranged between the pedal force detector and the rear tire for detecting the pedal force. The torque detector is arranged between the rear wheel disc and the hub of the bicycle, so that the original frame, the pedal crank, the crankshaft, the large disc and the like can be simply integrated into the rear wheel without changing the configuration, and the combination procedure is greatly simplified.

The technical means of the invention is to arrange a magnetic telescopic torque force detector on a fixed supporting shaft, comprising: a torque transmission sleeve made of metal with magnetic expansion property into hollow shell shape and pivoted with the fixed support shaft, wherein a pair of spiral ribs with opposite left and right rotation directions are formed at the middle section of the torque transmission sleeve, and the torque transmission sleeve is provided with a power input end and a power output end; a pair of magnetic conductive winding shafts made of high magnetic conductive material and surrounded by the pair of spiral ribs and fixed on the fixed supporting shaft; and a coil assembly wound on the pair of magnetic conductive winding shafts for detecting the magnetic permeability change generated by the pair of spiral ribs when the torque transmission sleeve is subjected to the torque load.

In further implementations, the present invention further includes:

Wherein the spiral rib is composed of a plurality of ribs which are arranged at equal intervals in the circumferential direction in a specific axle distance.

Wherein the pair of spiral ribs with opposite left and right rotation directions respectively has a spiral angle theta, and 0< | theta ≦ 45 degrees.

the magnetic conductive winding shaft is formed by a cylinder and a disc-shaped ear ring which respectively extends outwards in a radiation way along two sides of the cylinder. Wherein, an air gap is formed between the disc-shaped ear ring of the magnetic conductive bobbin and the torque transmission sleeve. Wherein, the magnetic conductive bobbin, the air gap and the spiral rib form a magnetic loop.

Wherein the coil assembly comprises a pair of inner exciting coils and a pair of outer measuring coils. Wherein the pair of excitation coils are connected in series in the same helical direction and the pair of measurement coils are connected in series in opposite helical directions. Alternatively, the pair of excitation coils are connected in series in opposite helical directions, and the pair of measurement coils are connected in series in the same helical direction.

Wherein the power input end of the torque transmission sleeve can be assembled with a rear wheel set (or called fly) of a bicycle

Wheel), a hub motor can be assembled at the power output end, and then according to the torque force detection embodiment, the magnetic telescopic torque force detector and the motor providing the power assistance can be simply integrated to the rear wheel of the bicycle.

In addition, the present invention further includes an electromagnetic wave isolation device with high conductivity and low permeability, comprising: a first electromagnetic wave isolation sleeve, which is arranged between the magnetic conductive winding shaft and the fixed support shaft and is fixedly connected with the magnetic conductive winding shaft and the fixed support shaft into a whole; the second electromagnetic wave isolation sleeve is tightly attached to the periphery of the torsion transmission sleeve; three electromagnetic wave isolation sheets are arranged at intervals and the side surfaces of the three electromagnetic wave isolation sheets are tightly attached to the magnetic conductive winding shaft. The electromagnetic wave shielding device is used for shielding the interference of electromagnetic waves transmitted from the outside and preventing the electromagnetic waves generated by the exciting coil from being diffused to the outside environment.

According to the above embodiment of the present invention, the technical originality and effect are as follows: the torque transmission mechanism with magnetic expansion and contraction characteristic is arranged on the outer layer to form a shell-shaped sleeve, spiral threads are engraved on the sleeve to form a transmission part connected by spiral ribs, when an excitation coil is electrified with alternating current, magnetic force lines generated by excitation can be intensively guided to pass through the spiral ribs, the central shaft is different from the traditional central shaft with the spiral ribs, a solid rod piece is still arranged below the spiral ribs, and the magnetic force lines can be dispersed to solid parts, so the magnetic expansion and contraction effect of the material can be more effectively expressed.

Furthermore, details relating to the technology with which the present invention may be practiced are set forth in the following detailed description and the accompanying drawings.

Drawings

Fig. 1 is an exploded perspective view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an embodiment of the present invention.

Fig. 3 is a cross-sectional view of the torque detector of the present invention.

Fig. 4 is a sectional view taken along line a-a of fig. 3.

FIG. 5 is a schematic diagram of a torque detector magnetic circuit according to an embodiment of the present invention.

Fig. 6 is a circuit diagram of a two-pair coil of the coil assembly of the present invention.

Fig. 7 is a diagram of the counterclockwise rotation of the hub motor ratchet set of the present invention as viewed from the left.

Fig. 8 is a diagram of the hub motor ratchet set of the present invention viewed from the left for clockwise motion.

Description of reference numerals: 10 a torque detector; 11a torque transmission sleeve; 11a, 11b helical ribs; 11c a power input; 11d power output end; 12a, 12b magnetic conductive winding shafts; 121 a cylinder; 122. 123 disc-shaped earrings; 13. 13a, 13b air gap; 14 coil groups; 15. 16 coils; 15a, 15b excitation coils; 16a, 16b measuring coils; 17a, 17b magnetic circuit; 20 a hub motor; 21 a motor reducer; 22 ratchet wheel sets; 23, a hub; 30 rear fluted disc group; 41 fixing the supporting shaft; 50. 51 a bearing; 61 a first electromagnetic wave isolation sleeve; 62 a second electromagnetic wave isolation sleeve; 63 an electromagnetic wave shielding sheet; h, wheelbase; theta a helix angle.

Detailed Description

first, referring to fig. 1 and fig. 2, the configuration details of a preferred embodiment of the present invention are disclosed, and the torque detector 10 provided by the present invention integrates the hub motor 20 with the rear wheel of the bicycle and is mounted on a fixed supporting shaft 41 used as a fixed end.

Referring to fig. 3 and 4, it can be seen that the torque detector 10 of the present invention includes: a torque transmission sleeve 11, a pair of magnetically permeable bobbins 12a, 12b and a coil assembly 14. The torque transmission sleeve 11 is made of metal with magnetic expansion (magnetic stretching) characteristics, such as chrome-molybdenum steel or nickel-chrome-molybdenum steel, and is hollow shell-shaped, a pair of spiral ribs 11a and 11b with opposite spiral directions are formed at the middle section of the torque transmission sleeve 11, a specific axial distance h (as shown in fig. 1) is kept between the pair of spiral ribs 11a and 11b in the axial direction of a fixed support shaft 41, and the pair of spiral ribs 11a and 11b consists of a plurality of ribs arranged circumferentially at equal pitch within the specific axial distance h; the pair of magnetic conductive bobbins 12a and 12b are surrounded by the pair of spiral ribs 11a and 11b, respectively, and fixed to the support shaft 41; the coil assembly 14 includes two pairs of coils 15, 16, the two pairs of coils 15, 16 are respectively wound on the pair of magnetic conductive bobbins 12a, 12b for detecting the magnetic permeability change generated on the pair of spiral ribs 11a, 11b when the torque transmission sleeve 11 is subjected to the torque load.

in practice, the pair of spiral ribs 11a, 11b have a respective helix angle θ (see fig. 1) that is relatively flared toward the radial direction of the fixed support shaft 41, and 0< | θ | ≦ 45 °, so that the pair of spiral ribs 11a, 11b are relatively each formed in a reverse helix. When the torque transmission sleeve 11 is subjected to a torque force, the pair of spiral ribs 11a, 11b are respectively subjected to a compressive force on one of them and a tensile force on the other, for example, if the spiral rib 11a is subjected to a compressive force, the spiral rib 11b is subjected to a tensile force, and if the torque transmission sleeve 11 is made of a material with positive magnetic expansion effect, the magnetic permeability of the spiral rib 11a is reduced and the magnetic permeability of the spiral rib 11b is increased.

The torque transmission sleeve 11 is pivotally connected to the fixed support shaft 41 at two ends thereof by bearings 50 and 51, and can stably rotate on the fixed support shaft 41.

The pair of magnetic-conductive bobbins 12a and 12b may be made of a high-magnetic-conductivity material, such as high-magnetic-conductivity martensite stainless steel, pure iron, nickel steel, or silicon steel, and the pair of magnetic-conductive bobbins 12a and 12b are symmetrically disposed in mirror symmetry with respect to the pair of spiral ribs 11a and 11b, respectively. The single magnetic conductive bobbin is formed by a cylinder 121 and disc-shaped ear rings 122, 123 extending radially outward along two sides of the cylinder 121. An air gap 13 is formed between the disc-shaped earrings 122, 123 and the torque transmission sleeve 11, and includes air gaps 13a, 13b corresponding to the disc-shaped earrings 122, 123, so as to avoid friction interference with the disc-shaped earrings 122, 123 when the torque transmission sleeve 11 rotates.

It should be further noted that the pair of spiral ribs 11a and 11b and the pair of magnetic conductive bobbins 12a and 12b surrounded by the pair of spiral ribs form a pair of magnetic circuits 17a and 17 b. The magnetic circuit 17a is formed by the cylinder 121, the disc-shaped ear ring 122, the air gap 13a, the spiral rib 11a, the air gap 13b, and the disc-shaped ear ring 123; the magnetic circuit 17b is formed by the cylinder 121, the disc-shaped ear ring 122, the air gap 13a, the spiral rib 11b, the air gap 13b, and the disc-shaped ear ring 123.

Please refer to fig. 3 and fig. 6, which illustrate that the two pairs of coils 15 and 16 included in the coil assembly 14 are a pair of exciting coils 15a and 15b and a pair of measuring coils 16a and 16b, respectively, and are respectively wound on the magnetic-conductive bobbins 12a and 12 b; more specifically, the pair of excitation coils 15a and 15b are respectively wound on the magnetic conductive bobbins 12a and 12b, and then the pair of measurement coils 16a and 16b are respectively wound on the magnetic conductive bobbins 12a and 12b, such that the pair of excitation coils 15a and 15b and the pair of measurement coils 16a and 16b are respectively interposed between the inner layer and the outer layer of the magnetic conductive bobbins 12a and 12 b. The number of winding turns of the exciting coil 15a and the exciting coil 15b is N, the number of winding turns of the measuring coil 16a and the measuring coil 16b is M, and M is usually a multiple of N.

Fig. 6 shows the wiring scheme adopted by the present invention, that is, the pair of exciting coils 15a, 15b are connected in series in the same spiral direction, and the pair of measuring coils 16a, 16b are connected in series in the opposite spiral direction. Other wiring schemes may be used in which the pair of excitation coils 15a, 15b are connected in series in opposite helical directions, and the pair of measurement coils 16a, 16b are connected in series in the same helical direction. When the pair of exciting coils 15a, 15b are supplied with ac sine wave power, that is, magnetic lines of force, that is, magnetic fluxes are generated on the pair of magnetic circuits 17a, 17b, and the strength and direction of the magnetic fluxes vary with sine waves of the ac power, according to the law of law, the measuring coils 16a, 16b thus induce alternating voltages Va, Vb, which can be expressed as the following mathematical expression:

Va＝Am×cos(ωt)

Vb＝Bm×cos(ωt)

Where Am is the peak voltage value induced by the measurement coil 16a, and Bm is the peak voltage value induced by the measurement coil 16 b.

Since the pair of measuring coils 16a, 16b are connected in series in opposite spiral directions, the voltages generated by the measuring coils 16a and 16b will cancel each other out, i.e. the voltage Vab in series of the pair of measuring coils 16a, 16b can be expressed as:

Vab＝Va-Vb＝(Am-Bm)×cos(ωt)

when the torque transmission sleeve 11 is not yet subjected to the torque load, the magnetic resistance of the magnetic circuit 17a is equal to the magnetic resistance of the magnetic circuit 17b, so that the inductance of the exciting coil 15a is equal to the inductance of the exciting coil 15b, and therefore the impedance thereof is equal, and the voltage division in the series circuit is equal, so that the voltage across the exciting coil 15a is equal to the voltage across the exciting coil 15b, and therefore the voltage Va induced by the measuring coils 16a and 16b is equal to Vb, that is, Am is equal to Bm, so that Vab is equal to 0. When the torque transmission sleeve 11 is under a torque load, if the spiral rib 11a is under a pressure, the spiral rib 11b is under a tension, and if the torque transmission sleeve 11 is made of a material with positive magnetostriction effect, the magnetic permeability of the spiral rib 11a is reduced, and the magnetic permeability of the spiral rib 11b is increased, so that the magnetic resistance of the magnetic circuit 17a is greater than the magnetic resistance of the magnetic circuit 17b, the inductance of the exciting coil 15a is smaller than the inductance of the exciting coil 15b, so that the impedance of the exciting coil 15a is smaller than the impedance of the exciting coil 15b, the partial voltage of the exciting coil 15a is smaller than the partial voltage of the exciting coil 15b on the series circuit, that is, the terminal voltage of the exciting coil 15a is smaller than the terminal voltage of the exciting coil 15b, so that the absolute value Va | < | Vb |, that Am < Bm ═ Va ═ Vb ═ xs (ω t) ≠ 0. In accordance with the foregoing, Vab is derived from the inductance difference of the pair of exciting coils 15a, 15b, which is derived from the magnetic permeability variation of the pair of spiral ribs 11a, 11b, that is, the magnitude variation of the torque force applied to the torque transmission sleeve 11, and according to the technical theory, the coil assembly 14 can be used to detect the torque force applied to the torque transmission sleeve 11.

Referring to fig. 1 and 3, it can be seen that the electromagnetic wave isolation device with high conductivity and low magnetic permeability according to the present invention comprises: a first EMI shielding sleeve 61, a second EMI shielding sleeve 62 and three EMI shielding sheets 63. Wherein, the first electromagnetic wave isolation sleeve 61 is disposed between the pair of magnetic-conductive bobbins 12a and 12b and the fixed support shaft 41 (as shown in fig. 4), and the first electromagnetic wave isolation sleeve 61, the pair of magnetic-conductive bobbins 12a and 12b and the fixed support shaft 41 are fixedly connected to form a whole; the second electromagnetic wave isolation sleeve 62 is tightly fitted around the torque transmission sleeve 11; the three electromagnetic wave shielding sheets 63 are spaced apart from each other and are closely attached to the pair of magnetic conductive bobbins 12a and 12b at side surfaces thereof. The electromagnetic wave shielding device is used for shielding the interference of electromagnetic waves transmitted from the outside and preventing the electromagnetic waves generated by the exciting coil from being diffused to the outside environment. It should be noted that the pair of magnetic conductive bobbins 12a, 12b, the coil assembly 14, the three electromagnetic wave shielding sheets 63, the first electromagnetic wave shielding sleeve 61 and the fixed support shaft 41 are integrally fixed; the second electromagnetic wave shielding sleeve 62 is tightly fitted around the torque transmission sleeve 11 and is pivoted to the fixed support shaft by bearings 50 and 51 to serve as a rotating member. A specific gap 13 is set between the rotating part and the fixing part, so that interference friction is avoided during rotation.

The torque transmission sleeve 11 further comprises a power input end 11c and a power output end 11 d. The power input end 11c of the torque transmission sleeve 11 can be assembled with a rear wheel disc set (or called flywheel) 30 of a bicycle, the power output end 11d can be assembled with a hub motor 20, and according to the torque detection embodiment, the magnetic stretching torque detector 10 and the hub motor 20 providing power assistance can be easily integrated with the rear wheel of the bicycle.

basically, the rear wheel set 30 already includes a ratchet set (not shown), and when the pedal force is applied to rotate the rear wheel set 30 counterclockwise as viewed from the left side of the bicycle, the rear wheel set 30 applies a torque to the torque transmission sleeve 11; conversely, when the rear disc set 30 is rotated clockwise, the rear disc set 30 does not apply a torque to the torque transmission sleeve 11.

In addition, the operation principle of the hub motor 20 should be described, and referring to fig. 2, it can be seen that the hub motor 20 includes: a motor reducer 21, a ratchet set 22, a hub 23. The internal mechanism of the motor reducer 21 will not be described in detail.

Referring now also to fig. 7 and 8, both views are taken from the left side of the bicycle (i.e., the left side of fig. 2). When the hub 23 rotates counterclockwise, which means the bicycle is in a forward direction, when the motor provides power to push the motor reducer 21 to rotate counterclockwise, the motor reducer 21 can engage the hub 23 by means of the ratchet set 22 to push the hub 23 to rotate counterclockwise synchronously (as shown in fig. 7); when the motor does not provide power, the motor reducer 21 does not rotate, and when the hub 23 rotates counterclockwise by other force, the ratchet set 22 does not provide the meshing function, and the motor reducer 21 and the hub 23 are not linked with each other (as shown in fig. 8).

According to the above arrangement details, when a cyclist applies a pedaling force to the pedals, a torque is applied to the rear chainset 30 via a chain (not shown), which is transmitted to the hub 23 to drive the bicycle against a load. In the process, the power input end 11c of the torque transmission sleeve 11 receives the torque force from the rear gear set 30, and the power output end 11d transmits the torque force to overcome the load (strictly speaking, the torque force required for accelerating the bicycle) encountered by the bicycle, the torque force is the same at each section perpendicular to the central axis on the torque transmission sleeve 11, and the helical ribs 11a and 11b will show pressure and tension in the directions of the helix angles of plus and minus 45 degrees, so that the helical ribs 11a and 11b bear the pressure, the magnetic permeability is reduced, and the magnetic permeability is increased. At the same time, the pair of excitation coils 15a, 15b are also applied with an alternating current power source to generate an alternating magnetic flux on the pair of magnetic circuits 17a, 17 b. As described above, the pair of measurement coils 16a and 16b can measure a series terminal voltage Vab-Vb (Am-Bm) xcos (ω t), and Am-Bm is proportional to the torque value, and the Vab signal is transmitted to a signal processing unit to control the hub motor to provide the assisting power at an appropriate time, and the assisting power can be calculated according to the magnitude of Vab, so as to reduce the pedaling force of the rider when the rider encounters a rough road or climbs.

In view of the above, it should be understood that the feasibility of the torque detector utilizing the magnetostriction effect according to the present invention is not obvious. However, the above examples are only for the purpose of illustrating preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention.

Claims

1. A torque detector is configured on a fixed support shaft, and is characterized by comprising:

A torque transmission sleeve made of metal with magnetic expansion property into a hollow shell shape and pivoted with the fixed support shaft, wherein a pair of spiral ribs with opposite left and right rotation directions are formed at the middle section of the torque transmission sleeve, and the torque transmission sleeve is provided with a power input end and a power output end;

A pair of magnetic conductive winding shafts made of high magnetic conductive material and surrounded by the pair of spiral ribs and fixed on the fixed supporting shaft; and

A coil set wound on the pair of magnetic conductive winding shafts for detecting the magnetic permeability change generated by the pair of spiral ribs when the torque transmission sleeve is subjected to torque load;

The pair of spiral ribs are respectively formed by engraving through spiral grains, magnetic lines of force generated by the excitation of the coil group can be intensively guided to pass through the spiral ribs, and the pair of spiral ribs and the pair of magnetic conductive winding shafts surrounded by the pair of spiral ribs form a pair of magnetic loops.

2. The torque detector of claim 1, wherein: the spiral rib is composed of a plurality of ribs arranged at equal intervals in the circumferential direction within a specific axle base.

3. the torque detector according to claim 1 or 2, wherein: the pair of spiral ribs with opposite left and right rotation directions respectively has a spiral angle theta, and 0< | theta ≦ 45 degrees.

4. the torque detector of claim 1, wherein: the magnetic conductive winding shaft is formed by a cylinder and a disc-shaped ear ring which respectively extends outwards in a radiation way along two sides of the cylinder.

5. the torque detector of claim 4, wherein: an air gap is formed between the disc-shaped ear ring of the magnetic conductive bobbin and the torque transmission sleeve.

6. The torque detector of claim 5, wherein: the magnetic circuit is formed among the magnetic conductive winding shaft, the air gap and the spiral rib.

7. the torque detector of claim 1, wherein: the coil assembly includes a pair of inner excitation coils and a pair of outer measurement coils.

8. The torque detector of claim 7, wherein: the pair of excitation coils are connected in series in the same helical direction, and the pair of measurement coils are connected in series in opposite helical directions.

9. The torque detector of claim 7, wherein: the pair of excitation coils are connected in series in opposite helical directions, and the pair of measurement coils are connected in series in the same helical direction.

10. The torque detector of claim 1, wherein: an electromagnetic wave isolation device is also provided, comprising:

The first electromagnetic wave isolation sleeve is arranged between each magnetic conduction winding shaft and the fixed support shaft, and the first electromagnetic wave isolation sleeve, the magnetic conduction winding shaft and the fixed support shaft are fixedly connected into a whole;

The second electromagnetic wave isolation sleeve is tightly sleeved on the periphery of the torsion transmission sleeve; and

three electromagnetic wave isolation sheets are respectively arranged at intervals and the side surfaces of the three electromagnetic wave isolation sheets are tightly attached to the magnetic conductive winding shaft.

11. The torque detector of claim 1, wherein: the power input end of the torque transmission sleeve is assembled with a rear wheel disc group of the bicycle, and the power output end is assembled with a hub motor.