Middle motor

Abstract

The utility model discloses a middle motor, which comprises a casing, a middle shaft, a motor, a transmission assembly and a rotating speed sensing assembly, the middle shaft is rotatably assembled in the casing, and two ends of the middle shaft extend out of the casing; the motor is used for driving the middle shaft to rotate; the transmission assembly is used for transmitting the output torque of the motor to the middle shaft; the rotating speed sensing assembly comprises a magnetic conductive gear ring and a sensing piece, a plurality of sensing parts which are uniformly distributed at intervals are formed on the magnetic conductive gear ring in the circumferential direction of the magnetic conductive gear ring, a hollow part is formed between every two adjacent sensing parts, the hollow parts are filled with insulating parts, the sensing piece and the magnetic conductive gear ring are arranged at intervals, and the sensing piece is located on a radial extension line of the magnetic conductive gear ring; the magnetic conductive gear ring is fixed to the middle shaft in a surrounding mode, when the middle shaft rotates, the middle shaft drives the magnetic conductive gear ring to rotate synchronously, and the sensing piece senses signals in the rotating process of the magnetic conductive gear ring. The centrally-mounted motor is small in size and compact in structure, and the detection precision of the rotating speed of the center shaft in the centrally-mounted motor is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of middle -position motor, especially a kind of middle -position motor. BACKGROUND

[0002] New energy bicycle is the current more fashionable riding equipment, and power assist is one of its characteristics, and various signals generated by the central shaft of the bicycle need to be detected during power assist, including the central shaft speed sensing device for detecting pedal frequency signal.The central shaft speed sensing device mainly includes a central shaft, a magnetically conductive gear ring fixed around the central shaft, and a sensing element arranged on the radial extension line of the magnetically conductive gear ring.During the driving of the bicycle, especially in the driving process under the power assist mode, the magnetically conductive gear ring rotates synchronously with the central shaft, and the magnetic field around the magnet steel is affected by the magnetically conductive gear ring and changes periodically, and the change frequency is positively correlated with the speed of the central shaft and the magnetically conductive gear ring - the faster the speed of the central shaft and the magnetically conductive gear ring, the faster the change frequency of the magnetic field.The sensing element senses the change frequency of the magnetic field in real time, and transmits the change frequency signal of the magnetic field to the control circuit board in the form of voltage, and the motor control changes the frequency to control the output parameters of the motor.

[0003] The magnetically conductive gear ring in the prior art is an outer gear ring structure, which includes a circular ring-shaped gear body coaxially arranged with the central shaft, and a plurality of convex teeth are integrally arranged on the outer peripheral surface of the gear body and uniformly distributed along the circumferential direction.When the magnetically conductive gear ring rotates, the convex teeth and the recessed structure between adjacent convex teeth will alternately correspond to the magnet, and when the convex teeth are opposite the sensing element, the sensing element can sense the magnetic signal and generate a Hall signal, and the processor outputs the pedal frequency signal after synthesizing the Hall signal;However, the convex teeth arranged on the outer peripheral surface of the gear body increase the radial size of the central shaft speed sensing device, thereby increasing the volume of the middle -position motor, and the recessed structure between adjacent convex teeth may also affect the electromagnetic influence of the magnet on the Hall, which may cause false detection. CONTENT OF THE UTILITY MODEL

[0004] In view of the deficiencies of the prior art, the utility model provides a middle -position motor, which is small in size, compact in structure and improves the detection accuracy of the central shaft speed in the middle -position motor.

[0005] The utility model realizes the following technical schemes:

[0006] A middle -position motor, comprising:

[0007] A casing;

[0008] A central shaft, which is rotatably assembled in the casing and has two ends extending out of the casing;

[0009] A motor, which is arranged in the casing for driving the central shaft to rotate;

[0010] a transmission assembly arranged in the casing for transmitting an output torque of the motor to the intermediate shaft;

[0011] a rotating speed sensing assembly comprising a magnetically conductive gear ring and a sensing member, the magnetically conductive gear ring is formed with a plurality of evenly spaced induction portions along a circumferential direction thereof, and a hollow portion is formed between two adjacent induction portions, the hollow portion is filled with an insulating portion, and the sensing member is arranged in a radial extension line of the magnetically conductive gear ring.

[0012] The magnetically conductive gear ring is fixed around the intermediate shaft, and the intermediate shaft drives the magnetically conductive gear ring to rotate synchronously when the intermediate shaft rotates, and the sensing member senses a signal during rotation of the magnetically conductive gear ring.

[0013] Further, the rotating speed sensing assembly further comprises a mounting ring, the mounting ring is integrally formed by injection molding and fixedly sleeved on the intermediate shaft, and the insulating portion is integrally formed on the mounting ring.

[0014] Further, the magnetically conductive gear ring is in a circular ring structure, and the magnetically conductive gear ring is embedded on an outer circumferential surface of the mounting ring.

[0015] Further, the rotating speed sensing assembly further comprises a mounting bracket, the mounting bracket is fixed in the casing, and the sensing member is fixed on the mounting bracket.

[0016] Further, the sensing member comprises a magnetic member and a speed Hall element, the magnetic member and the speed Hall element are both mounted on the mounting bracket, and the speed Hall element is located between the magnetically conductive gear ring and the magnetic member.

[0017] Further, a thickness of the magnetically conductive gear ring in a radial direction is 0.8-1mm.

[0018] Further, a circumferential dimension of the induction portion is consistent with that of the hollow portion, and a sum of circumferential dimensions of the plurality of induction portions: a sum of circumferential dimensions of the plurality of hollow portions is 1:1.

[0019] Further, a material of the insulating portion is plastic.

[0020] Further, an outer circumferential surface of the mounting ring is provided with a mounting groove adapted to the magnetically conductive gear ring, the magnetically conductive gear ring is mounted in the mounting groove, and the insulating portion is integrally formed on a bottom wall of the mounting groove by injection molding.

[0021] Further, the magnetic member and the speed Hall element are fixed by a heat shrink tube.

[0022] Further, the outer circumferential surface of the middle shaft is sleeved with a shaft sleeve, and the mounting ring is fixedly sleeved on the shaft sleeve.

[0023] Further, the mounting frame comprises a ring sleeve sleeved on the middle shaft, the magnetic member and the speed Hall element are mounted in the ring sleeve, and the magnetically conductive gear ring is arranged on the inner side of the ring sleeve.

[0024] Further, the magnetic member and the speed Hall element are located on the radial extension line of the magnetically conductive gear ring.

[0025] Further, the projection size of the speed Hall element on the magnetically conductive gear ring is consistent with the size of the induction part.

[0026] Further, the speed Hall element is provided with two, and the two speed Hall elements are distributed along the circumference of the magnetically conductive gear ring; when one of the speed Hall elements corresponds to the induction part, the other speed Hall element corresponds to the insulation part.

[0027] Further, the distance between the magnetic member and the magnetically conductive gear ring in the radial direction is 1.9-2.1mm.

[0028] Further, the speed Hall element is electrically connected with a control circuit board, the control circuit board is electrically connected with the motor, in the driving process in the bicycle assisting mode, the magnetically conductive gear ring rotates synchronously with the middle shaft, the magnetic field around the magnetic member is influenced by the induction part of the magnetically conductive gear ring and changes periodically, the speed Hall element in real time induces the magnetic field change frequency of the magnetic member around and transmits the magnetic field change frequency signal to the control circuit board in the form of voltage, and the control circuit board controls the output parameter of the motor according to the magnetic field change frequency signal.

[0029] Compared with the prior art, the utility model has the advantages that:

[0030] 1, through the magnetically conductive gear ring is sleeved on the mounting ring, and the magnetically conductive gear ring is provided with a plurality of evenly distributed induction parts along the circumference, and the hollow part is formed between adjacent induction parts. Compared with the full metal gear ring, the non-induction part of the magnetically conductive gear ring adopts the hollow structure, and the hollow structure is filled with insulating material. On the one hand, the required installation space of the magnetically conductive gear ring in the radial direction can be reduced, the overall structure is compact, and the weight is reduced. On the other hand, in the process of induction signal, the insulating material has no influence on the induction signal compared with the original metal material, thereby ensuring the accuracy of the induction signal. And the magnetically conductive gear ring is matched with the mounting ring. The mounting ring not only can support the magnetically conductive gear ring, but also can prevent the magnetically conductive gear ring from deforming during installation and operation.

[0031] 2. By using heat shrink tube to fix between the magnetic member and the speed hall element. Compared with the glue fixing, it can greatly simplify the process operation, reduce the production of bad, and effectively avoid the falling of the back magnet. Specifically, the aging phenomenon will occur in the glue bonding process during long-term use, and the working mode of the riding equipment often appears the phenomenon of jolt, so it is easy to cause the phenomenon of falling of the magnetic member relative to the speed hall element. The use of heat shrink tube wrapping and fixing solves the above problems; in addition, the glue bonding needs to align the magnetic member and the speed hall element, and needs a certain glue solidification time, which not only has great positioning difficulty, but also has long cycle; the use of heat shrink tube can correct the wrapping process, and does not need to wait for time, short cycle, and simple process. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the middle shaft speed detection part;

[0033] Figure 2 It is a sectional view of the middle shaft speed detection part Figure 1 ;

[0034] Figure 3 It is a sectional view of the middle shaft speed detection part Figure 2 ;

[0035] Figure 4 It is an assembly drawing of the mounting ring and the magnetism tooth circle;

[0036] Figure 5 It is a schematic diagram of the structure of the magnetism tooth circle;

[0037] Figure 6 It is a front view of the middle shaft speed detection part;

[0038] Figure 7 It is Figure 6 the sectional view along A-A.

[0039] 2, middle shaft; 3, speed sensing assembly; 30, mounting ring; 300, insulation part; 31, magnetism tooth circle; 310, hollow part; 311, induction part; 32, mounting frame; 320, ring sleeve; 33, magnetic member; 34, speed hall element; 35, heat shrink tube; 36, shaft sleeve; 37, control circuit board. DETAILED DESCRIPTION

[0040] The utility model discloses further non-restrictive detailed description of technical scheme to the utility model and its drawings in combination with preferred embodiments. In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" are based on the orientation or positional relationship shown in the drawings. In addition, the terms "first", "second" are only for the purpose of description, and can not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the utility model, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise explicitly specified. The embodiments described below by referring to the drawings are exemplary, and are intended to explain the utility model, and can not be understood as limiting the utility model.

[0041] As Figures 1-7 The utility model discloses an embodiment of a middle motor for being installed in the middle part of the electric bicycle frame to drive the bicycle to travel. The middle motor includes a casing, a middle shaft 2, a motor, a transmission assembly and a torque sleeve pipe, the middle shaft 2 is rotatably assembled in the casing, and the both ends of the middle shaft 2 extend out of the casing, and a support bearing is arranged between the middle shaft 2 and the casing. The motor is arranged in the casing for driving the middle shaft 2 to rotate, the transmission assembly is arranged in the casing for transmitting the output torque of the motor to the middle shaft 2, the torque sleeve pipe is coaxially sleeved on the outside of the middle shaft 2, and one end of the torque sleeve pipe is fastened with the middle shaft 2, and the other end is provided with a cogwheel connecting part, and the torque sleeve pipe has a certain deformation capacity, and will produce circumferential torsional deformation when subjected to circumferential torsional force. The torque sensing device corresponding to the torque sleeve pipe indirectly obtains the pedaling force of the rider on the middle shaft 2 by sensing the deformation amount of the torque sleeve pipe.

[0042] The motor includes a rotor and a stator, and the rotor and the stator are arranged in the casing, and the stator is relatively fixed with the casing. In actual application, a crank is connected to the both ends of the middle shaft 2, the aforementioned cogwheel connecting part on one end of the torque sleeve pipe is installed with a cogwheel, the cogwheel is connected with the sprocket of the rear wheel of the bicycle through a chain, and the rotor is drivingly connected with the cogwheel through the transmission assembly. In the pure electric or power-assisted mode, the motor is powered to make the rotor rotate, the rotor drives the cogwheel to rotate through the transmission assembly, the cogwheel drives the rear wheel to rotate through the chain, and the bicycle moves forward. In the pure riding mode, the rider pedals the pedals on the crank to drive the middle shaft 2 to rotate, the middle shaft 2 drives the cogwheel to rotate through the torque sleeve pipe, and the cogwheel drives the rear wheel to rotate through the chain, and the bicycle moves forward.

[0043] As Figure 2 , figures andFigure 5 In the embodiment, the middle motor further comprises a rotating speed sensing assembly 3, which comprises a magnetically conductive gear ring 31 and a sensing member. The magnetically conductive gear ring 31 is formed with a plurality of evenly spaced sensing portions 311 along the circumference thereof, and a hollow portion 310 is formed between any two adjacent sensing portions 311. The hollow portion 310 is filled with an insulating portion 300. The sensing member is arranged in a spaced manner with the magnetically conductive gear ring 31 and is located on the radial extension line of the magnetically conductive gear ring 31. The magnetically conductive gear ring 31 is fixedly arranged around the middle shaft 2. When the middle shaft 2 rotates, the middle shaft 2 drives the magnetically conductive gear ring 31 to rotate synchronously, and the sensing member senses signals during the rotation of the magnetically conductive gear ring 31.

[0044] The rotating speed sensing assembly 3 further comprises a mounting ring 30 which is integrally formed by injection molding and fixedly sleeved on the middle shaft 2. Further, the outer circumferential surface of the middle shaft 2 is tightly sleeved with a shaft sleeve 36, and the mounting ring 30 is fixedly sleeved on the shaft sleeve 36.

[0045] In the embodiment, the insulating portion 300 is integrally formed on the mounting ring 30, further strengthening the stability of the installation between the magnetically conductive gear ring 31 and the mounting ring 30.

[0046] The rotating speed sensing assembly 3 further comprises a mounting bracket 32 which is fixed in the shell by screws, and the sensing member is fixed on the mounting bracket 32. Further, the sensing member comprises a magnetic member 33 and a speed Hall element 34, both of which are mounted on the mounting bracket 32, and the speed Hall element 34 is located between the magnetically conductive gear ring 31 and the magnetic member 33.

[0047] In actual application, the speed Hall element 34 is electrically connected with a control circuit board 37 which is electrically connected with the motor. During the driving of the bicycle, especially in the driving process in the assist mode, the magnetically conductive gear ring 31 rotates synchronously with the middle shaft 2. The magnetic field around the magnetic member 33 is periodically changed due to the influence of the sensing portions 311 of the magnetically conductive gear ring 31, and the change frequency is positively correlated with the rotating speed of the middle shaft 2 and the magnetically conductive gear ring 31. The faster the rotating speed of the middle shaft 2 and the magnetically conductive gear ring 31, the faster the change frequency of the magnetic field around the magnetic member 33. The speed Hall element 34 senses the change frequency of the magnetic field around the magnetic member 33 in real time, and transmits the magnetic field change frequency signal to the control circuit board 37 in the form of voltage. The control circuit board 37 controls the output parameters of the motor according to the magnetic field change frequency signal.

[0048] The mounting bracket 32 comprises a ring sleeve 320 which is sleeved on the middle shaft 2, and the magnetic member 33 and the speed Hall element 34 are both mounted in the ring sleeve 320. The magnetically conductive gear ring 31 is arranged on the inner side of the ring sleeve 320.

[0049] In order to enhance the influence of the magnetically conductive gear ring 31 on the magnetic field around the magnetic member 33, in the embodiment, the magnetic member 33 and the speed Hall element 34 are both located on the radial extension line of the magnetically conductive gear ring 31.

[0050] As shown in Figures 4-5 the magnetic tooth circle 31 is sleeved on the mounting ring 30, and in the process of rotating with the middle shaft 2, the magnetic member 33 alternately corresponds to the induction part 311 and the hollow part 310. When the induction part 311 corresponds to the magnetic member 33, the speed Hall element 34 generates a Hall signal. Compared with the full-metal tooth circle, the non-induction part of the magnetic tooth circle 31 adopts a hollow structure, and the hollow structure is filled with insulating material. On the one hand, the required installation space of the magnetic tooth circle 31 in the radial direction can be reduced, the overall structure is compact, and the weight is reduced. On the other hand, in the process of induction signal, the insulating material has no effect on the induction signal compared with the original metal material, thereby ensuring the accuracy of the induction signal. Moreover, the magnetic tooth circle 31 is matched with the mounting ring 30, and the mounting ring 30 can not only support the magnetic tooth circle 31, but also prevent the magnetic tooth circle 31 from deforming during installation and work.

[0051] In this embodiment, the magnetic tooth circle 31 is a circular ring structure, and the thickness of the magnetic tooth circle 31 in the radial direction is 0.8-1mm, which further effectively reduces the installation space of the magnetic tooth circle 31 in the radial direction.

[0052] In this embodiment, the hollow part 310 is filled with an insulating part 300, and the material of the insulating part 300 is plastic. When the magnetic member 33 passes through the induction part 311 and the insulating part 300, the magnetic field generated by the magnetic member 33 passing through the magnetic field of the speed Hall element 34 is very different, or in other words, when passing through the insulating part 300, the magnetic field generated by the magnetic member 33 passing through the magnetic field of the speed Hall element 34 is very small, which cannot make the speed Hall element 34 conduct, thereby generating a change in high and low levels. Compared with the full-metal tooth circle, the magnetic field influence of the insulating part 300 on the speed Hall element 34 is much lower than that of the induction part 311, so the induction of the speed Hall element 34 is more obvious and accurate.

[0053] The magnetic tooth circle 31 is embedded on the outer circumferential surface of the mounting ring 30. Specifically, the outer circumferential surface of the mounting ring 30 is provided with a mounting groove matched with the magnetic tooth circle 31, and the magnetic tooth circle 31 is installed in the mounting groove. Only the induction part 311 of the magnetic tooth circle 31 is exposed, and the other parts are wrapped, reducing the contact area with air and reducing the risk of rusting of the magnetic tooth circle 31, thereby improving the stability and reliability of the frequency signal output and prolonging the service life.

[0054] In this embodiment, the sizes of the induction part 311 and the hollow part 310 in the circumferential direction are consistent, and the sum of the sizes of the plurality of induction parts 311 in the circumferential direction: the sum of the sizes of the plurality of hollow parts 310 in the circumferential direction is 1:1, which is for cooperation with the speed Hall element 34.

[0055] In the embodiment, the projected size of the speed Hall element 34 on the magnetically conductive tooth ring 31 is consistent with the size of the sensing portion 311.

[0056] In the embodiment, two speed Hall elements 34 are arranged, and the two speed Hall elements 34 are distributed along the circumference of the magnetically conductive tooth ring 31. When one of the speed Hall elements 34 corresponds to the sensing portion 311, the other speed Hall element 34 corresponds to the insulation portion 300, so that the pedal frequency signal can be continuously monitored without interruption.

[0057] In the embodiment, the insulation portion 300 is integrally formed on the bottom wall of the mounting groove by injection molding, which further strengthens the stability of the installation between the magnetically conductive tooth ring 31 and the mounting ring 30.

[0058] As shown in Figure 3 In the embodiment, the heat shrink tube 35 is used to fix the magnetic member 33 and the speed Hall element 34. Compared with the glue fixing, the process operation can be greatly simplified, the production defects can be reduced, and the falling of the back magnet can be effectively avoided. Specifically, the aging phenomenon may occur in the glue bonding process during long-term use, and the working mode of the riding equipment often appears to be jolted, so that the magnetic member 33 is easily separated from the speed Hall element 34. The use of the heat shrink tube 35 solves the above problems. In addition, the magnetic member 33 and the speed Hall element 34 need to be aligned when the glue is bonded, and a certain glue solidification time is required. This not only has a large positioning difficulty, but also has a long cycle. The use of the heat shrink tube 35 can correct the position during the wrapping process, and does not need to wait for a certain time, so the cycle is short and the process is simple.

[0059] In the embodiment, the mounting bracket 32 includes a ring sleeve 320 sleeved on the middle shaft 2, and the magnetic member 33 and the speed Hall element 34 are mounted in the ring sleeve 320. The magnetically conductive tooth ring 31 is arranged on the inner side of the ring sleeve 320.

[0060] As shown in Figure 7 In the embodiment, the distance d between the magnetic member 33 and the magnetically conductive tooth ring 31 in the radial direction is 1.9-2.1 mm.

[0061] The strength of the magnetic member 33 is selected in the range of 300-400 mT.

[0062] The torque sensing device capable of sensing the deformation amount of the torque sleeve corresponding to the torque sleeve is specifically structured as follows:

[0063] A circle of magnetically conductive sheets is fixed around the outer periphery of the torque sleeve, and a plurality of holes are arranged on the magnetically conductive sheets in the circumferential direction. The magnetically conductive sheets are coaxially sleeved with the excitation coil and the induction coil (the two coils constitute a coupled coil), and the excitation coil and the induction coil are fixed on the mounting bracket 32.

[0064] In actual application, the excitation coil is connected with the excitation voltage (alternating power supply), and the induction coil is connected with the control circuit board 37 of the middle motor. The voltage signal obtained after the induction coil signal is processed by the circuit is transmitted to the control circuit board 37 of the middle motor through CAN. According to electromagnetic effect, the excitation coil generates alternating current under the action of the excitation voltage, and further generates alternating electromagnetic field around the excitation coil. Under the action of the aforementioned alternating electromagnetic field, alternating induction voltage is generated on the induction coil. Generally, because the size (and frequency) of the excitation voltage is fixed, the alternating induction voltage generated on the induction coil is also fixed. When the rider pedals the crank, the torque sleeve is twisted and deformed, and the magnetically conductive sheet fixed on the periphery of the torque sleeve is also twisted and deformed, thereby causing the hole on the magnetically conductive sheet to be deformed. The deformation of the magnetically conductive sheet changes the size of the electromagnetic field generated by the excitation coil, and further causes the size of the induction voltage on the induction coil to change. The greater the change of the induction voltage is, the greater the mechanical deformation of the torque sleeve is, and the greater the pedaling torque applied to the middle shaft 2 by the rider is. The induction coil transmits the induction voltage signal generated by the induction coil to the control circuit board 37 in real time, and the control circuit board 37 adjusts the output parameters of the motor according to the size of the signal change.

[0065] It is mentioned above that the rotor 3 is in transmission connection with the toothed disc installed at the end of the torque sleeve, and the torque sleeve is in the transmission path of the rotor 3 and the toothed disc. The rotor 3 is in transmission connection with the torque sleeve through the transmission assembly, and a one-way clutch is arranged in the transmission path of the rotor 3 and the torque sleeve. In the pure electric or assist mode, the rotor 3 drives the torque sleeve to rotate through the transmission assembly (at this time, the aforementioned one-way clutch is in the locked state), the torque sleeve drives the toothed disc to rotate, the toothed disc drives the rear wheel to rotate through the chain, and the bicycle moves forward. In the pure riding mode, the rider pedals the pedal on the crank to drive the middle shaft 2 to rotate, the middle shaft 2 drives the toothed disc to rotate through the torque sleeve (at this time, the aforementioned one-way clutch is in the separated state, and the rotor will not rotate), and the toothed disc drives the rear wheel to rotate through the chain, and the bicycle moves forward.

[0066] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present application. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. An electric motor, characterized in that Include: The shell; The middle shaft (2) is rotatably assembled in the shell, and the two ends of the middle shaft (2) extend out of the shell; The motor is arranged in the shell for driving the middle shaft (2) to rotate; The transmission assembly is arranged in the shell for transmitting the output torque of the motor to the middle shaft (2); The rotating speed sensing assembly (3) comprises a magnetically conductive gear ring (31) and a sensing part, the magnetically conductive gear ring (31) is formed with a plurality of evenly distributed induction parts (311) along the circumference, and a hollow part (310) is formed between adjacent two induction parts (311), the hollow part (310) is filled with an insulating part (300), and the sensing part is arranged in the magnetically conductive gear ring (31) and the sensing part is located on the radial extension line of the magnetically conductive gear ring (31); The magnetically conductive gear ring (31) is fixed around the middle shaft (2), when the middle shaft (2) rotates, the middle shaft (2) drives the magnetically conductive gear ring (31) to rotate synchronously, and the sensing part senses the signal in the process of rotating the magnetically conductive gear ring (31).

2. The line start motor of claim 1, wherein, The rotating speed sensing assembly (3) further comprises a mounting ring (30), the mounting ring (30) is integrally formed by injection molding and fixedly sleeved on the middle shaft (2), and the insulating part (300) is integrally formed on the mounting ring (30).

3. The line start motor of claim 2, wherein, The magnetically conductive gear ring (31) is a circular ring structure, and the magnetically conductive gear ring (31) is embedded on the outer circumferential surface of the mounting ring (30).

4. The line start motor of claim 1, wherein, The rotating speed sensing assembly (3) further comprises a mounting bracket (32), the mounting bracket (32) is fixed in the shell, and the sensing part is fixed on the mounting bracket (32).

5. An IPM as set forth in claim 4, characterized by The sensing part comprises a magnetic part (33) and a speed Hall element (34), the magnetic part (33) and the speed Hall element (34) are installed on the mounting bracket (32), and the speed Hall element (34) is located between the magnetically conductive gear ring (31) and the magnetic part (33).

6. The line start motor of claim 3 wherein, The thickness of the magnetically conductive gear ring (31) in the radial direction is 0.8-1mm.

7. An electric machine according to claim 1, characterized in that The size of the induction part (311) and the hollow part (310) in the circumferential direction is consistent, and the sum of the sizes of the induction part (311) and the hollow part (310) in the circumferential direction is 1:

1.

8. The line start motor of claim 1, wherein, The material of the insulating part (300) is plastic.

9. An electric machine according to claim 3, characterized in that The outer circumferential surface of the mounting ring (30) is provided with a mounting groove matched with the magnetically conductive gear ring (31), the magnetically conductive gear ring (31) is installed in the mounting groove, and the insulating part (300) is integrally formed on the bottom wall of the mounting groove by injection molding.

10. The line start motor of claim 5 wherein, The magnetic part (33) and the speed Hall element (34) are fixed by a heat shrink tube (35).

11. The line start motor of claim 2 wherein, The outer circumferential surface of the middle shaft (2) is tightly sleeved with a shaft sleeve (36), and the mounting ring (30) is fixedly sleeved on the shaft sleeve (36).

12. The line start motor of claim 5 wherein, The mounting frame (32) comprises a sleeve (320) sleeved on the middle shaft (2), the magnetic member (33) and the speed Hall element (34) are both mounted in the sleeve (320), and the magnetically conductive tooth ring (31) is arranged on the inner side of the sleeve (320).

13. The line start motor of claim 5 wherein, The magnetic member (33) and the speed Hall element (34) are both located on the radial extension line of the magnetically conductive tooth ring (31).

14. The line start motor of claim 5 wherein, The projection size of the speed Hall element (34) on the magnetically conductive tooth ring (31) is consistent with the size of the induction part (311).

15. The line start motor of claim 14, wherein, The speed Hall element (34) is provided with two, and the two speed Hall elements (34) are distributed along the circumference of the magnetically conductive tooth ring (31), when one of the speed Hall elements (34) corresponds to the induction part (311), the other speed Hall element (34) corresponds to the insulation part (300).

16. The line start motor of claim 5 wherein, The distance (d) between the magnetic member (33) and the magnetically conductive tooth ring (31) in the radial direction is 1.9-2.1mm.

17. The line start motor of claim 5 wherein, The speed Hall element (34) is electrically connected with a control circuit board (37), the control circuit board (37) is electrically connected with the motor, in the driving process in the bicycle assisting mode, the magnetically conductive tooth ring (31) rotates synchronously with the middle shaft (2), the magnetic field around the magnetic member (33) is influenced by the induction part (311) of the magnetically conductive tooth ring (31) and changes periodically, the speed Hall element (34) in real time inducts the magnetic field change frequency around the magnetic member (33), and the magnetic field change frequency signal is transmitted to the control circuit board (37) in the form of voltage, and the control circuit board (37) controls the output parameter of the motor according to the magnetic field change frequency signal.

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