Stepping motor

Abstract

The present invention provides a stepping motor, comprising a rotating shaft, magnetic steels fixed to the outer peripheral side of the shaft, and a winding unit sleeved on the rotating shaft and rotatably connected to the rotating shaft. The winding unit comprises at least one winding, each winding being spaced apart from the magnetic steels. Each winding comprises a housing sleeved on the rotating shaft, a bobbin fixed to the housing, two first claw poles fixed to two ends of the housing, two second claw poles fixed to a middle region of the bobbin, and two coils wound on the bobbin and spaced apart from each other. Two opposite sides of the housing in each winding are provided with notches passing through the side wall of the housing. The stepping motor of the present invention allows the effective volume of an entire magnetic circuit to be increased, and the torque performance can also be improved by approximately 15%.

Description

Stepper motor Technical Field

[0001] This invention relates to the field of motor technology, and more particularly to a stepper motor for use in foldable screen mobile phones. Background Technology

[0002] Stepper motors have been widely used in most technical fields, such as electric motors, generators, and folding machines, due to their compact structure, high efficiency, and energy saving.

[0003] In the field of folding, as shown in Figure 1, the automatic folding hinge 101 used in the foldable screen phone 100 requires a stepper motor. In order to make the foldable screen phone 100 thinner and lighter, its thickness in the Z-axis direction needs to be further reduced, that is, the arrangement space in the Z-axis direction needs to be reduced. However, the arrangement space in the Y-axis direction is relatively loose and does not need to be further reduced. Under this condition of limited arrangement space in the Z-axis direction, in order to ensure that the automatic folding of the foldable screen phone 100 is not affected, it is necessary to ensure that the output torque of the stepper motor is large enough.

[0004] In related technologies, as shown in Figures 2 and 3, the motor 200 mainly includes a shaft 210, a magnet 220 fixed to the outer periphery of the shaft 210, a winding structure 230 sleeved on the shaft 210 and rotatably connected to the shaft 210, and a flexible circuit board fixed to the winding structure 230 and electrically connected to the winding structure 230. The winding structure includes four winding groups 230. Each winding group 230 includes a shell 2301 sleeved on the shaft 210 and formed by the side wall, a bracket 2302 fixed to the inner side of the shell 2301, a first claw pole structure 2303 fixed to the shell 2301 and extending into the bracket 2302, a second claw pole structure 2304 fixed to the bracket 2302 and facing the first claw pole structure 2303, a coil structure 2305 fixed to the outer side of the bracket 2302, and a winding column 2306 fixed to the outer side of the bracket 2302. The outer shell 2301 is rotatably connected to the shaft 210 through a cover plate 2307 and a bearing body 2308. In order to limit the second claw pole structure 2304, a small slot 240 needs to be designed on the side of the shell 2301. In order to allow the winding column 2306 to pass through, a large slot 250 needs to be designed on the side of the shell 2301.

[0005] In summary, the small slots 240 and large slots 250 designed on the housing 2301 of the motor 200 in the related technology are both for creating avoidance positions. This design means that the size of the motor 200 is limited in one direction, and the volume of the magnet 220, the side wall of the housing 2301, the first claw pole structure 2303, the second claw pole structure 2304 and the coil structure 2305 are also limited in one direction, resulting in a smaller torque of the motor 200.

[0006] Therefore, it is necessary to provide a new stepper motor to solve the above-mentioned technical problems. Technical issues

[0007] The purpose of this invention is to provide a new stepper motor to solve the problem that the housing design of motors in related technologies leads to low torque. Technical solutions

[0008] To achieve the above objectives, the present invention provides a stepper motor, which includes a rotating shaft, a magnet fixed to the outer periphery of the rotating shaft, and a winding unit sleeved on the rotating shaft and rotatably connected to the rotating shaft. The winding unit includes at least one winding arranged along the axial direction of the rotating shaft, and each winding is spaced apart from the magnet.

[0009] Each winding includes a housing sleeved on and rotatably connected to the shaft, a frame fixed to the inner side of the housing and coaxially arranged with the housing, two first claw poles fixed to both ends of the housing, two second claw poles fixed to the middle region of the frame and extending into the frame, and two coils wound around the outer periphery of the frame and spaced apart; the housing is annular and formed by sidewalls, each second claw pole extends into the frame and is fixedly connected to the frame, each first claw pole is opposite to and cooperates with a corresponding second claw pole, and each coil is located outside a corresponding first claw pole and a second claw pole; slots penetrating the sidewalls are provided on opposite sides of the housing in each winding.

[0010] Preferably, the two second claw poles in each winding are respectively embedded in the corresponding skeleton, and are integrally formed with the corresponding skeleton by insert injection molding.

[0011] Preferably, the stepper motor further includes a flexible circuit board fixed to the winding unit and electrically connected to the winding unit. The flexible circuit board is fixed to the skeleton in each winding and electrically connected to all coils in each winding.

[0012] Preferably, the central region of the skeleton in each winding is provided with a protruding extension that extends through the housing, and four protruding winding posts are provided at intervals on the side of the extension away from the skeleton. The four winding posts are respectively inserted and fixed to the flexible circuit board; the two ends of the two coils in each winding are respectively wound around the four winding posts and electrically connected to the flexible circuit board.

[0013] Preferably, the winding post and the extension in each winding are integrally formed with the skeleton by injection molding.

[0014] Preferably, the magnet is a sintered magnet.

[0015] Preferably, the magnets include a plurality of magnets, which are arranged around the rotating shaft and fixed to the outer periphery of the rotating shaft, and the plurality of magnets are arranged at intervals between each other.

[0016] Preferably, each of the first claw poles and each of the second claw poles includes an annular fixing portion and a plurality of bent portions extending axially from the inner periphery of the fixing portion, the plurality of bent portions being spaced apart and all extending into the skeleton; the bent portions of each first claw pole are located between two bent portions of the corresponding second claw pole, and the bent portions of each second claw pole are located between two bent portions of the corresponding first claw pole.

[0017] Preferably, the inner side of the skeleton in each winding is provided with a plurality of inwardly recessed grooves, the shapes of the plurality of grooves respectively matching the plurality of bent portions of the first claw pole and the plurality of bent portions of the second claw pole, and the plurality of bent portions of the first claw pole and the plurality of bent portions of the second claw pole are respectively housed and fixed in the corresponding grooves.

[0018] Preferably, each of the first claw poles is integrally formed with the corresponding housing.

[0019] Preferably, the winding unit includes a plurality of windings arranged axially along the rotating shaft, the housings of the plurality of windings are fixedly connected in sequence, and the corresponding slots of the plurality of windings are interconnected along the axial direction of the rotating shaft.

[0020] Preferably, each winding's housing includes a hollow first outer shell and a second outer shell stacked on top of each other along the axial direction of the rotating shaft, with the slots respectively disposed on the first and second outer shells; the two outer windings further include a cover fixed to the end of the first outer shell away from the second outer shell, the first outer shell of the two outer windings being further away from the other winding relative to the second outer shell, the cover being fixed to the rotating shaft by a bearing and forming a rotatable connection with the rotating shaft, the cover having an inwardly recessed notch corresponding to the position of the slot; the two first claw poles of each winding are respectively disposed at the ends of the first and second outer shells that are far apart from each other. Beneficial effects

[0021] Compared with related technologies, the stepper motor in this invention achieves limiting by fixing the second claw pole to the frame and opening slots through its sidewalls on opposite sides of the housing to achieve one-way avoidance. This allows the stepper motor to further increase the volume of the magnet, the first claw pole, the second claw pole, and the coil within the same size. Although the volume of the sidewalls of the housing is reduced, overall, it releases the space of the effective magnetic circuit composed of the magnet and the coil, increasing the effective volume of the entire magnetic circuit and improving the torque performance by about 15%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0023] Figure 1 is a structural schematic diagram of a foldable screen phone provided by related technologies;

[0024] Figure 2 is a three-dimensional structural diagram of a stepper motor provided by related technologies;

[0025] Figure 3 is an exploded view of the structure of a stepper motor provided by related technologies;

[0026] Figure 4 is a three-dimensional structural diagram of the stepper motor provided in an embodiment of the present invention;

[0027] Figure 5 is an exploded view of the structure of the stepper motor provided in an embodiment of the present invention;

[0028] Figure 6 is a cross-sectional view along line AA in Figure 4;

[0029] Figure 7 is a schematic diagram of the frame structure in the stepper motor provided in an embodiment of the present invention.

[0030] In Figures 4 to 7: 300, stepper motor; 1, shaft; 2, magnet; 3, winding; 31, housing; 311, slot; 312, first outer shell; 313, second outer shell; 314, shallow slot; 32, frame; 321, extension; 322, winding post; 323, groove; 33, first claw pole; 331, fixing part; 332, bending part; 34, second claw pole; 35, coil; 4, flexible circuit board; 5, cover; 51, notch; 6, bearing; 7, gasket. Embodiments of the present invention

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a stepper motor 300, as shown in Figures 4 to 7. It includes a rotating shaft 1, a magnet 2 fixed to the outer periphery of the rotating shaft 1, a winding unit sleeved on the rotating shaft 1 and rotatably connected to the rotating shaft 1, and a flexible circuit board 4 fixed to the winding unit and electrically connected to the winding unit. The winding unit includes at least one winding 3 arranged along the axial direction of the rotating shaft 1, and each winding 3 is spaced apart from the magnet 2.

[0033] In this embodiment, the magnet 2 is a sintered magnet. The magnetic remanence of the magnet 2 is one of the factors affecting the torque performance of the stepper motor 300. Since the magnet 2 can be in the shape of a ring or formed by multiple magnets 2 surrounding a ring with a small diameter, if the magnet 2 is fixed by bonding, its magnetic remanence is low, which is not conducive to improving the torque performance of the stepper motor 300. However, the magnet 2 in this embodiment is a sintered magnet, and its magnetic remanence is increased by more than 50% compared with the bonding method, which can effectively improve the torque performance of the stepper motor 300. This is suitable for situations where the size of the stepper motor 300 is limited in one direction.

[0034] Of course, fixing the magnet 2 by bonding also has advantages: the mold imaging is convenient to prepare, multi-pole magnetization is possible, it is simple and convenient, and it is conducive to mass production; using sintered magnets also has disadvantages: it cannot be directly molded and cannot be multi-pole magnetized. It needs to go through slicing → magnetization → patching → grinding → powder removal → electroplating in sequence, which is a complex and immature process with high cost.

[0035] The magnets 2 include multiple magnets, which are arranged around the rotating shaft 1 and fixed to the outer periphery of the rotating shaft 1, with the magnets 2 spaced apart from each other. In this embodiment, there are eight magnets 2 arranged at equal intervals. Of course, the number of magnets 2 can be adapted to meet actual needs.

[0036] Specifically, each winding 3 includes a housing 31 sleeved on and rotatably connected to the rotating shaft 1, a frame 32 fixed to the inner side of the housing 31 and coaxially arranged with the housing 31, two first claw poles 33 respectively fixed to both ends of the housing 31, two second claw poles 34 fixed to the middle region of the frame 32, and two coils 35 respectively wound around the outer periphery of the frame 32 and spaced apart. The housing 31 is annular and formed by side walls. Each second claw pole 34 extends into the frame 32 and is fixedly connected to the frame 32. Each first claw pole 33 is opposite to and cooperates with a corresponding second claw pole 34. Each coil 35 is located outside a corresponding first claw pole 33 and a second claw pole 34. The housing 31 in each winding 3 has slots 311 through its side walls on opposite sides.

[0037] The flexible circuit board 4 is fixed to the frame 32 in each winding 3, and the flexible circuit board 4 is electrically connected to all the coils 35 in each winding 3.

[0038] Each winding 3 has a protruding extension 321 in the middle region of the skeleton 32 that extends through the housing 31. On the side of the extension 321 away from the skeleton 32, there are four protruding winding posts 322. The four winding posts 322 are respectively inserted and fixed to the flexible circuit board 4. The two ends of the two coils 35 in each winding 3 are respectively wound on the four winding posts 322 and electrically connected to the flexible circuit board 4.

[0039] The winding post 322 and extension 321 in each winding 3 are integrally molded with the frame 32 by injection molding. This design uses integrally molded plastic pins, eliminating the need for injection molding of metal pin inserts used in related technologies, thus avoiding the instability and easy detachment of metal pins in small sizes.

[0040] As shown in Figures 2 and 3, the coil structure 2305, the first claw pole structure 2303, and the second claw pole structure 2304 of the motor 200 in the related technology are separate parts. The coil structure 2305 is wound and fixed on the bracket 2302. The four coil structures 2305 are installed in sequence, and the winding cylinders 2306 are uniformly arranged in one direction. The disadvantage is that a large slot 250 must be opened on the side wall of the outer shell 2301 to avoid this, which results in the torque performance of the motor 200 not being fully improved and occupies the side space. The bracket 2302 is injection molded, and its radial thickness needs to be at least 0.15mm, which wastes the arrangement space.

[0041] In this embodiment, the two second claw poles 34 in each winding 3 are respectively embedded into the corresponding frame 32, and both are integrally formed with the corresponding frame 32 by insert injection molding. With this design, the radial thickness of the frame 32 can be reduced to 0.08, which effectively increases the magnetic circuit space of the stepper motor 300. Moreover, the housing 31 is installed from both sides of the coil 35, so there is no need to open a large slot. Only a shallow slot 314 is needed to meet the assembly requirements, which effectively increases the side wall height of the housing 31 and effectively improves the torque performance of the stepper motor 300.

[0042] Each first claw pole 33 is integrally formed with the corresponding housing 31.

[0043] Each first claw pole 33 and each second claw pole 34 includes an annular fixing portion 331 and a plurality of bent portions 332 extending axially from the inner periphery of the fixing portion 331. The plurality of bent portions 332 are spaced apart and all extend into the frame 32. The bent portions 332 of each first claw pole 33 are located between the two bent portions 332 of the corresponding second claw pole 34, and the bent portions 332 of each second claw pole 34 are located between the two bent portions 332 of the corresponding first claw pole 33.

[0044] The fixing part 331 of each first claw pole 33 is fixed to one end of the housing 31, and the fixing part 331 of each second claw pole 34 is fixed to the middle region of the corresponding frame 32. This design ensures the stability of the first claw pole 33 and the second claw pole 34 and allows both to extend into the frame 32 to be adapted to the corresponding coil 35.

[0045] Each winding 3 has a plurality of inwardly recessed grooves 323 on the inner side of the frame 32. The shapes of the grooves 323 respectively match the multiple bends 332 of the first claw pole 33 and the multiple bends 332 of the second claw pole 34. The multiple bends 332 of the first claw pole 33 and the multiple bends 332 of the second claw pole 34 are respectively received and fixed in the corresponding grooves 323. This design can limit the first claw pole 33 and the second claw pole 34 respectively through the grooves 323 designed on the frame 32.

[0046] Specifically, the winding unit includes multiple windings 3 arranged axially along the shaft 1. The housings 31 of the multiple windings 3 are fixedly connected in sequence, and the corresponding slots 311 of the multiple windings 3 are interconnected along the shaft 1. In this embodiment, the winding unit includes two windings 3.

[0047] Each winding 3 has a housing 31 comprising a hollow first outer shell 312 and a second outer shell 313 stacked on top of each other along the axial direction of the shaft 1. Slots 311 are respectively provided on the first outer shell 312 and the second outer shell 313. The two outer windings 3 also include a cover 5 fixed to the end of the first outer shell 312 away from the second outer shell 313. The first outer shell 312 of the two outer windings 3 is further away from the other winding 3 than the second outer shell 313. The cover 5 is fixed to the shaft 1 by a bearing 6 and forms a rotatable connection with the shaft 1. The cover 5 has an inwardly recessed notch 51 corresponding to the position of the slot 311. Two first claw poles 33 in each winding 3 are respectively provided at the ends of the first outer shell 312 and the second outer shell 313 that are far apart from each other. This design not only facilitates the rotatable connection between the housing 31 and the shaft 1, but also facilitates the assembly and disassembly of the housing 31 and the design of the slots 311.

[0048] In addition, the stepper motor 300 also includes two spacers 7 sleeved on the rotating shaft 1 and spaced apart from each other, with the two spacers 7 respectively abutting against both ends of the magnet 2. This design can strengthen the fixing strength between the magnet 2 and the rotating shaft 1.

[0049] The stepper motor 300 in this embodiment can be applied to the automatic folding hinge of a foldable screen phone.

[0050] Compared with related technologies, the stepper motor 300 in this embodiment achieves limiting by fixing the second claw pole 34 to the frame 32, and opens slots 311 through its sidewalls on opposite sides of the housing 31 to achieve one-way avoidance. This allows the stepper motor 300 to further increase the volume of the magnet 2, the first claw pole 33, the second claw pole 34 and the coil 35 within the same size. Although the volume of the sidewall of the housing 31 is reduced, overall, it releases the space of the effective magnetic circuit composed of the magnet 2 and the coil 35, increases the effective volume of the entire magnetic circuit, and improves the torque performance by about 15%.

[0051] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements all fall within the protection scope of the present invention.

Claims

1. A stepper motor, characterized in that, The stepper motor includes a rotating shaft, a magnet fixed to the outer periphery of the rotating shaft, and a winding unit sleeved on the rotating shaft and rotatably connected to the rotating shaft. The winding unit includes at least one winding arranged along the axial direction of the rotating shaft, and each winding is spaced apart from the magnet. Each winding includes a housing sleeved on and rotatably connected to the shaft, a frame fixed to the inner side of the housing and coaxially arranged with the housing, two first claw poles fixed to both ends of the housing, two second claw poles fixed to the middle region of the frame, and two coils wound around the outer periphery of the frame and spaced apart; the housing is annular and formed by sidewalls, each second claw pole extends into the frame and is fixedly connected to the frame, each first claw pole is opposite to and cooperates with a corresponding second claw pole, and each coil is located outside a corresponding first claw pole and a second claw pole; slots penetrating the sidewalls are provided on opposite sides of the housing in each winding.

2. The stepper motor as described in claim 1, characterized in that, The two second claw poles in each winding are respectively embedded in the corresponding skeleton, and are integrally formed with the corresponding skeleton by insert injection molding.

3. The stepper motor as described in claim 1, characterized in that, The stepper motor further includes a flexible circuit board fixed to the winding unit and electrically connected to the winding unit. The flexible circuit board is fixed to the skeleton in each winding and electrically connected to all coils in each winding.

4. The stepper motor as described in claim 3, characterized in that, Each of the windings has a protruding extension in the middle region of the skeleton that extends through the housing. On the side of the extension away from the skeleton, there are four protruding winding posts spaced apart. The four winding posts are respectively inserted and fixed to the flexible circuit board. The two ends of the two coils in each winding are respectively wound around the four winding posts and electrically connected to the flexible circuit board.

5. The stepper motor as described in claim 4, characterized in that, The winding post and the extension in each winding are integrally formed with the skeleton by injection molding.

6. The stepper motor as described in claim 1, characterized in that, The magnet is a sintered magnet.

7. The stepper motor as described in claim 6, characterized in that, The magnets include multiple magnets, which are arranged around the rotating shaft and fixed to the outer periphery of the rotating shaft, and the multiple magnets are arranged at intervals with each other.

8. The stepper motor as described in claim 1, characterized in that, Each of the first claw poles and each of the second claw poles includes an annular fixing portion and a plurality of bent portions extending axially from the inner periphery of the fixing portion, the plurality of bent portions being spaced apart and all extending into the skeleton; the bent portions of each first claw pole are located between two bent portions of the corresponding second claw pole, and the bent portions of each second claw pole are located between two bent portions of the corresponding first claw pole.

9. The stepper motor as described in claim 8, characterized in that, The inner side of the skeleton in each winding is provided with a plurality of inwardly recessed grooves. The shapes of the plurality of grooves are respectively matched with the plurality of bent portions of the first claw pole and the plurality of bent portions of the second claw pole. The plurality of bent portions of the first claw pole and the plurality of bent portions of the second claw pole are respectively housed and fixed in the corresponding grooves.

10. The stepper motor as described in claim 1, characterized in that, Each of the first claw poles is integrally formed with the corresponding housing.

11. The stepper motor as described in claim 1, characterized in that, The winding unit includes multiple windings arranged axially along the rotating shaft, the housings of the multiple windings are fixedly connected in sequence, and the corresponding slots of the multiple windings are interconnected along the rotating shaft.

12. The stepper motor as described in claim 11, characterized in that, Each winding's housing includes a hollow first outer shell and a second outer shell stacked on top of each other along the axial direction of the rotating shaft. The slots are respectively disposed on the first outer shell and the second outer shell. The two outer windings also include a cover fixed to the end of the first outer shell away from the second outer shell. The first outer shell of the two outer windings is further away from the other winding than the second outer shell. The cover is fixed to the rotating shaft by a bearing and forms a rotatable connection with the rotating shaft. The cover has an inwardly recessed notch corresponding to the position of the slot. The two first claw poles of each winding are respectively disposed at the ends of the first outer shell and the second outer shell that are far apart from each other.

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