A permanent magnet finite angle motor

Abstract

This invention discloses a permanent magnet finite angle motor, comprising a stator assembly, a rotor assembly, and an angle sensing assembly coaxially arranged. The rotor assembly includes a rotating shaft, two bearings mounted on the rotating shaft, and an annular magnet. The annular magnet is disposed between the two bearings. The stator assembly includes a winding mechanism and a stall plate. The winding mechanism includes a coil, a frame, and two iron cores. A non-uniformly distributed gap is formed between the iron cores and the annular magnet. The frame is provided around the periphery of the two iron cores, and the coil is disposed within the frame. The angle sensing assembly is sleeved on the rotating shaft and corresponds to the position of the other bearing. A spring assembly is provided on the side of the angle sensing assembly facing away from the annular magnet. By using an annular magnet, the motor can be given more stable magnetic capability and higher reliability. By optimizing the magnetic gap of the iron cores, the magnetic circuit distribution can be gradually improved. This not only increases the magnetic force of the rotor but also effectively shortens the rotation and engagement time of the motor.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a permanent magnet finite angle motor. Background Technology

[0002] Miniaturized motors have a wide range of applications. From a macroscopic perspective, they are widely used in key areas such as ignition devices and vehicle drive systems; from a microscopic perspective, miniaturized motors are also suitable for servo valve operation in home appliances and furniture, as well as various drive systems that achieve operation through small-angle rotation.

[0003] As mechanical and drive products continue to evolve towards miniaturization, the specifications of power and drive devices within these devices are also becoming increasingly smaller. During the design process, it is necessary to maximize performance while further reducing size, ensuring good drive performance and ease of installation. However, existing limited-angle motors are too large and have insufficient output torque to meet these requirements. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a permanent magnet finite angle motor, which aims to solve the technical problems mentioned in the background art.

[0005] A permanent magnet finite angle motor includes a stator assembly, a rotor assembly, and an angle sensing assembly coaxially arranged. The rotor assembly includes a rotating shaft, two bearings mounted on the rotating shaft, and an annular magnet. The annular magnet is disposed between the two bearings. The stator assembly includes a winding mechanism and a stall plate. The winding mechanism includes a coil, a frame, and two iron cores. The iron cores correspond to the positions of the annular magnets, and a non-uniformly distributed gap is formed between the iron cores and the annular magnets. The frame is disposed around the periphery of the two iron cores. The coil is disposed within the frame. After magnetization, the polarities of the two iron cores are different. The stall plate is connected to one of the bearings. The angle sensing assembly is sleeved on the rotating shaft and corresponds to the position of the other bearing. The angle sensing assembly is used to sense the rotation angle of the rotating shaft. A spring assembly is disposed on the side of the angle sensing assembly facing away from the annular magnet.

[0006] The beneficial effects of this invention are:

[0007] By employing toroidal magnets, the motor gains more stable magnetic capabilities and higher reliability. During operation, when the coil is energized, the generated magnetic poles are distributed tangentially around the circumference, producing thrust and resistance to drive the motor shaft. Optimizing the core magnetic gap gradually improves the magnetic circuit distribution, increasing the rotor's magnetic force and effectively shortening the motor's engagement time. Furthermore, the motor utilizes a design where the coil is fully enclosed by a frame. This frame features high insulation, high strength, and high thermal stability, reliably isolating the housing from the coil and effectively preventing short circuits, thus significantly improving the motor's operational reliability. While maintaining a compact size and high reliability, this motor still possesses powerful torque output capabilities. Its switching time is short, utilizing a stall plate to limit the shaft's rotation angle, allowing for precise small-angle rotations. Finally, a spring assembly quickly resets the shaft.

[0008] Furthermore, the angle sensing component includes an outer ring, an inner ring, and a plurality of brushes. The outer ring is disposed on the housing, and the inner ring is sleeved on the rotating shaft. The outer ring is provided with a plurality of brushes, each brush including a brush blade and brush filaments connected to the brush blade. The brush blade is connected to the outer ring. The inner ring includes an insulating member and a metal member disposed on the insulating member. The insulating member is sleeved on the rotating shaft, and the metal member has an arc-shaped portion. The brush filaments abut against the periphery of the arc-shaped portion.

[0009] Furthermore, the spring assembly includes a support, a return spring, and a fixing post. The support is connected to the housing. A plurality of first protrusions are spaced apart on the side of the support facing away from the housing. One end of the return spring is connected to one of its first protrusions, and the other end of the return spring is elastically connected to the rotating shaft. The fixing post is provided on the rotating shaft, and the fixing post abuts against the return spring.

[0010] Furthermore, one end of the rotating shaft is provided with a groove, and the return spring includes a bent portion and a straight portion provided at one end of the bent portion. The straight portion is connected to the bent portion and is located in the groove. The end of the bent portion away from the straight portion is provided with a bent portion. The bent portion is connected to the bent portion and is adapted to the first protrusion.

[0011] Furthermore, the skeleton includes two symmetrically arranged first skeleton bodies, each of which is provided with a first receiving groove and a second receiving groove. The first receiving groove and the second receiving groove are spaced apart. The two first receiving grooves are used to accommodate the iron core, and the two second receiving grooves are used to accommodate the coil.

[0012] Furthermore, the skeleton includes a second skeleton body, on which a first accommodating space is provided. The first accommodating space is used to accommodate the iron core. Third accommodating slots are provided at opposite ends of the first accommodating space. The first accommodating space and the two third accommodating slots are spaced apart. The two third accommodating slots are used to accommodate the coil.

[0013] Furthermore, the angle between the two opposite ends of the iron core is 120°~160°.

[0014] Furthermore, one side of the stall plate protrudes to form two second protrusions, which are located on opposite sides of the periphery of the stall plate. The rotating shaft is also provided with a limiting part, which is located between one of the bearings and the annular magnet. The limiting part includes a limiting body, a first limiting protrusion, and a second limiting protrusion. The first limiting protrusion and the second limiting protrusion are provided on the limiting body. The second protrusion corresponds to the position of the first limiting protrusion and is positioned towards the annular magnet.

[0015] Furthermore, the included angle formed by the two second protrusions is greater than the included angle formed by the arcuate portion.

[0016] Furthermore, the rotor assembly also includes an annular magnet protective ring, which is disposed between the annular magnet and the iron core.

[0017] Furthermore, the annular magnet is provided with a positioning groove, which is adapted to the second limiting protrusion. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art 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.

[0019] Figure 1 This is a schematic diagram of the permanent magnet finite angle motor according to the first embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the rotating shaft according to the first embodiment of the present invention. Figure 1 ;

[0021] Figure 3 This is a schematic diagram of the structure of the rotating shaft according to the first embodiment of the present invention. Figure 2 ;

[0022] Figure 4 This is a schematic diagram of the skeleton structure of the first embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of the stall plate according to the first embodiment of the present invention;

[0024] Figure 6 This is a schematic diagram of the structure of the annular magnet according to the first embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the structure of the annular magnet and iron core according to the first embodiment of the present invention;

[0026] Figure 8 This is a schematic diagram of the angle sensing component according to the first embodiment of the present invention. Figure 1 ;

[0027] Figure 9 This is a schematic diagram of the angle sensing component according to the first embodiment of the present invention. Figure 2 ;

[0028] Figure 10 This is a schematic diagram of the spring assembly according to the first embodiment of the present invention;

[0029] Figure 11 This is a schematic diagram of the structure of the reset spring according to the first embodiment of the present invention;

[0030] Figure 12 This is a schematic diagram of the skeleton structure of the second embodiment of the present invention.

[0031] In the diagram: 1. Stator assembly; 11. Winding mechanism; 111. Coil; 112. Frame; 1121. First frame body; 11211. First receiving groove; 11212. Second receiving groove; 1123. Second frame body; 11231. First receiving space; 11232. Third receiving groove; 113. Iron core; 12. Stalling plate; 121. Second protrusion; 2. Rotor assembly; 21. Shaft; 211. Groove; 212. Limiting part; 2121. Limiting body; 2122. First limiting protrusion; 2123. Second limiting part. 1. Protrusion; 22. Bearing; 23. Ring magnet; 231. Positioning groove; 24. Ring magnet protective ring; 3. Angle sensing assembly; 31. Outer ring; 311. First terminal; 32. Inner ring; 321. Insulating component; 322. Metal component; 3221. Arc-shaped part; 3222. Second terminal; 33. Brush; 331. Brush blade; 332. Brush filament; 4. Spring assembly; 41. Support; 411. First protrusion; 42. Return spring; 421. Bending part; 4211. Bending part; 422. Straight part; 43. Fixing post.

[0032] The embodiments of the present invention will be further described below with reference to the accompanying drawings. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain embodiments of the present invention, and should not be construed as limiting the present invention.

[0034] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] Example 1

[0037] A permanent magnet finite angle motor, such as Figures 1 to 11 As shown, it includes a stator assembly 1, a rotor assembly 2, an angle sensing assembly 3, and a spring assembly 4 arranged coaxially.

[0038] Specifically, the rotor assembly 2 includes a rotating shaft 21, two bearings 22 mounted on the rotating shaft 21, an annular magnet 23, and an annular magnet protective ring 24. The two bearings 22 are spaced apart, and the annular magnet 23 is disposed between the two bearings 22. The rotating shaft 21 is also provided with a limiting part 212, which is located between one of the bearings 22 and the annular magnet 23. The limiting part 212 includes a limiting body 2121, a first limiting protrusion 2122, and a second limiting protrusion 2123. The first limiting protrusion 2122 and the second limiting protrusion 2123 are disposed on the limiting body 2121. The second protrusion 121 corresponds to the position of the first limiting protrusion 2122, and the second limiting protrusion 2123 faces the annular magnet 23. The annular magnet protective ring 24 is located between the annular magnet 23 and the iron core 113. The annular magnet 23 is provided with a positioning groove 231, which is adapted to the second limiting protrusion 2123. The annular magnet 23 provides magnetic force for switching the polarity circuit of the motor. When the motor rotates, the entire rotating shaft 21 rotates under the action of electromagnetic force. The annular magnet 23 interacts with the magnetic field generated by the current of the coil 111, thereby generating rotational force. The annular magnet 23 is made of NdFeB material, which has high magnetic properties and high temperature resistance. The positioning groove 231 on the annular magnet 23 facilitates the assembly with the second limiting protrusion 2123 of the rotating shaft 21 and facilitates the differentiation of the north and south pole orientations during magnetization.

[0039] It should be noted that the toroidal magnet 23 has higher energy conversion efficiency and lower energy loss, which can improve energy utilization efficiency, generate greater magnetic force, and provide a uniform magnetic field, which helps the motor to run smoothly. The toroidal magnet 23 is designed to save space and is easy to integrate and assemble. Combined with materials with high magnetic energy product, it has a large magnetic field strength and high torque.

[0040] Specifically, the stator assembly 1 includes a winding mechanism 11 and a stall plate 12. The winding mechanism 11 includes a coil 111, a frame 112, and two iron cores 113. After magnetization, the two iron cores 113 have different polarities, namely N pole and S pole, respectively. The positions of the iron cores 113 and the toroidal magnets 23 correspond, and a non-uniformly distributed gap is formed between the iron cores 113 and the toroidal magnets 23. The frame 112 includes two first frame bodies 1121 symmetrically arranged along the central axis. Each of the two first frame bodies 1121 is provided with a first receiving groove 11211. The first and second receiving slots 11211 and 11212 are spaced apart. The two first receiving slots 11211 are used to receive the iron core 113, and the two second receiving slots 11212 are used to receive the coil 111. The angle between the two opposite ends of the iron core 113 is 152°. The magnetic gap between the iron core 113 and the annular magnet 23 is not uniformly distributed, which realizes the high torque design of the motor. The corresponding air gap pressure drop increases accordingly, and the magnetic pressure drop that balances it increases, the excitation current increases, and the power factor increases. Since leakage reactance is inversely proportional to air gap, a decrease in total leakage reactance leads to an increase in torque and motor efficiency. On the other hand, while ensuring torque, the motor's heat dissipation and rotational reliability are maintained, increasing the motor's service life. Coil 111 is the core of the motor signal source. According to the principle of electromagnetic induction, after being energized, coil 111 magnetizes iron core 113, thereby generating electromagnetic force. This electromagnetic force forms a tangential magnetic force after generating a magnetic circuit with toroidal magnet 23. Coil 111 is wound on the first frame body 1121 and located in the second receiving groove 11212, thereby using the first frame body 1121 to separate coil 111 from iron core 113. The first frame body 1121 is made of PEEK polyetheretherketone, which has high strength, high insulation, and high thermal stability, and can meet the requirements of structural strength, insulation, and temperature resistance. The coil 111 is wrapped with a polyimide insulating protective film to isolate the housing from the coil 111, achieving the insulation requirements between the housing and the lead wire.

[0041] It should be noted that the addition of the iron core 113 improves the efficiency of the motor. This is because the iron core 113 reduces magnetic leakage, thus minimizing the waste of electromagnetic energy. The gap between the iron core 113 and the toroidal magnet 23 decreases from the edge to the center, resulting in better efficiency of the initial tangential magnetic force and faster motor operation. The angle between the two opposite ends of the iron core 113 is 152°. The larger the angle, the greater the magnetic force coverage of the toroidal magnet 23. However, it cannot reach 180°, which would balance the attractive and repulsive forces of the iron core 113 on the toroidal magnet 23, preventing the toroidal magnet 23 from rotating.

[0042] Specifically, the stall plate 12 is connected to one of its bearings 22. One side of the stall plate 12 has two protrusions 121. The two protrusions 121 are located on opposite sides of the periphery of the stall plate 12. When the shaft 21 is stalled, the first limiting protrusion 2122 abuts against the second protrusions 121, thereby forming a stall and ensuring that the shaft 21 rotates clockwise or counterclockwise within a limited angle. The included angle formed by the two second protrusions 121 is greater than the included angle formed by the arc-shaped portion 3221, thereby ensuring that the shaft 21 rotates within the angle formed by the two second protrusions 121. When rotating within the angular range, the rotation angle of the rotating shaft 21 covers the range of rotation of the sensing angle. The rotation of the rotating shaft 21 drives the adapter shaft, which in turn drives the metal part 322 to rotate through the transmission insulation part 321. The rotation of the metal part 322 is connected to the brush bristles 332 at different positions and the connecting wires, forming a path when the rotating shaft 21 rotates at different rotation angles, thereby obtaining the specific rotation angle range of the rotating shaft 21. The stall plate 12 is made of stainless steel, which has excellent corrosion resistance, mechanical properties, oxidation resistance, and high temperature resistance, making it suitable as a mechanical stall material.

[0043] Specifically, the angle sensing component 3 is sleeved on the rotating shaft 21 and corresponds to the position of another bearing 22. The angle sensing component 3 is used to sense the rotation angle of the rotating shaft 21. The angle sensing component 3 includes an outer ring portion 31, an inner ring portion 32, and multiple brushes 33. The outer ring portion 31 is disposed on the housing, and the inner ring portion 32 is sleeved on the rotating shaft 21. Multiple brushes 33 are disposed on the outer ring portion 31. Each brush 33 includes a brush blade 331 and brush filaments 332 connected to the brush blade 331. The brush blade 331 is connected to the outer ring portion 31. The inner ring portion 32 includes an insulating member 321 and a metal part disposed on the insulating member 321. 322, the insulating component 321 is sleeved on the rotating shaft 21, the metal component 322 has an arc-shaped part 3221, the brush bristles 332 abut against the periphery of the arc-shaped part 3221, the insulating component 321 is connected to the rotating shaft 21 through the adapter shaft, the brush blade 331 is an elastic traction arm to fix the brush bristles 332 and ensure long-term stable and reliable contact, the brush bristles 332 are made of precious metal wear-resistant material, to maintain reliable contact and ensure low contact resistance during long-term and repeated use, the rotating shaft 21 drives the insulating component 321 to rotate, forming a connection between the metal component 322 and the brush bristles 332, so as to obtain the change of the rotation angle of the rotating shaft 21.

[0044] It should be noted that the two first protrusions 411 form a 100° angle. After the motor drives the motor, relative movement occurs between the outer ring 31 and the inner ring 32, corresponding to an angular deflection of the inner ring 32 from -5° to 95°. Different angles in different areas are distinguished by varying contact positions between the brush bristles 332 and the metal part 322. The outer ring 31 has multiple first terminals 311, and the metal part 322 has two second terminals 3222. Adjacent first terminals 311 are connected to the gray and yellow wires, respectively, and the two second terminals 3222 are connected to the brown-blue wire I and brown-blue wire II, respectively. Both brown-blue wire I and brown-blue wire II are connected to an external power source. The conduction status corresponding to different rotation angles of the rotating shaft 21 is as follows:

[0045] In the range of -5° to 20°, the gray line and brown-blue line I, as well as the yellow line and brown-blue line II, are all in an open circuit state.

[0046] In the 20° to 85° range, the gray line is conductive with brown-blue line I, and the yellow line is open-circuited with brown-blue line II.

[0047] In the 85° to 95° range, the gray line is fully connected to the brown-blue line I and the yellow line is fully connected to the brown-blue line II, as detailed in Table 1.

[0048] Table 1

[0049]

[0050] Specifically, the angle sensing component 3 has a spring assembly 4 on the side facing away from the annular magnet 23. The spring assembly 4 includes a support 41, a return spring 42, and a fixing post 43. The support 41 is connected to the housing. A plurality of first protrusions 411 are spaced apart on the side of the support 41 facing away from the housing. One end of the return spring 42 is connected to one of its first protrusions 411, and the other end of the return spring 42 is elastically connected to the rotating shaft 21. The fixing post 43 is provided on the rotating shaft 21 and abuts against the return spring 42. The return spring 42 includes a bent portion 421 and a straight portion 422 provided at one end of the bent portion 421. The straight portion 422 is connected to the bent portion 421. One end of the rotating shaft 21 is provided with a groove 211, and the straight portion 422 is located in the groove 211. The bent portion 421 is away from the straight portion 421. One end of the straight portion 422 is provided with a bent portion 4211, which is connected to the bent portion 421. The axis of the return spring 42 is provided with a straight portion 422 and is fixed in the groove 211. The fixing post 43 restricts the straight portion 422 in the groove 211 so that it does not come out. The bent portion 4211 is engaged with a first protrusion 411. By connecting with the first protrusion 411 at different positions, the return torque of the return spring 42 is changed. When the rotating shaft 21 rotates clockwise, the return spring 42 contracts and provides a restoring force for the rotation of the rotating shaft 21. When the rotating shaft 21 needs to be reset, the return spring 42 drives the rotating shaft 21 to rotate counterclockwise to reset. This structure makes full use of the elastic potential energy of the return spring 42, ensuring efficient operation while saving energy.

[0051] Specifically, the main function of the housing is to fix the entire motor structure and to provide magnetic conductivity and magnetic shielding. Therefore, stainless steel, which is corrosion-resistant, high-temperature resistant, and impact-resistant, is selected.

[0052] This invention, by employing a ring magnet 23, endows the motor with more stable magnetic capabilities and higher reliability. During motor operation, after the two coils 111 are energized, their magnetic poles are distributed tangentially around the circumference, generating thrust and resistance to drive the shaft 21 to rotate. By optimizing the magnetic gap of the iron core 113, the magnetic circuit distribution can be gradually improved. This not only increases the rotor's magnetic force but also effectively shortens the motor's rotation engagement time. Furthermore, the motor adopts a design where the coils 111 are surrounded by a frame 112. The frame 112 features high insulation, high strength, and high thermal stability, reliably isolating the housing from the coils 111 and effectively preventing short circuits in the coils 111, thereby significantly improving the reliability of motor operation. This motor, while ensuring a compact size and high reliability, still possesses powerful torque output capabilities. Its switching time during operation is short. The stall plate 12 forms a limit on the rotation angle of the shaft 21, thereby precisely completing small-angle rotations. Finally, the spring assembly 4 quickly resets the shaft 21.

[0053] Example 2

[0054] The difference from Example 1 is that:

[0055] Specifically, such as Figure 12 As shown, the frame 112 includes a second frame body 1123. The second frame body 1123 is provided with a first receiving space 11231, which is used to receive the iron core 113. The two opposite ends of the first receiving space 11231 are provided with third receiving grooves 11232. The first receiving space 11231 and the two third receiving grooves 11232 are spaced apart. The two third receiving grooves 11232 are used to receive the coil 111. The second frame body 1123 is a whole. During the injection molding process, the iron core 113 is placed in the second frame body 1123 and integrally formed. The second frame body 1123 separates the coil 111 from the iron core 113 and wraps the coil 111, so that the coil 111 is separated from the housing and avoids the risk of short circuit.

[0056] Specifically, the angle between the two opposite ends of the iron core 113 is 125°.

[0057] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A permanent magnet finite angle motor, characterized in that: The device includes a stator assembly, a rotor assembly, and an angle sensing assembly arranged coaxially. The rotor assembly includes a rotating shaft, two bearings mounted on the rotating shaft, and an annular magnet. The annular magnet is positioned between the two bearings. The stator assembly includes a winding mechanism and a stall plate. The winding mechanism includes a coil, a frame, and two iron cores. The iron cores correspond to the positions of the annular magnets, and a non-uniformly distributed gap is formed between the iron cores and the annular magnets. The frame is provided around the periphery of the two iron cores. The coil is located inside the frame. After magnetization, the polarities of the two iron cores are different. The stall plate is connected to one of the bearings. The angle sensing assembly is sleeved on the rotating shaft and corresponds to the position of the other bearing. The angle sensing assembly is used to sense the rotation angle of the rotating shaft. A spring assembly is provided on the side of the angle sensing assembly facing away from the annular magnet. The angle sensing component includes an outer ring, an inner ring, and several brushes. The outer ring is disposed on the housing, and the inner ring is sleeved on the rotating shaft. Several brushes are disposed on the outer ring, and each brush includes a brush blade and brush filaments connected to the brush blade. The brush blade is connected to the outer ring. The inner ring includes an insulating member and a metal member disposed on the insulating member. The insulating member is sleeved on the rotating shaft, and the metal member has an arc-shaped portion. The brush filaments abut against the periphery of the arc-shaped portion. One side of the stall plate has two second protrusions, which are located on opposite sides of the periphery of the stall plate. The rotating shaft is also provided with a limiting part, which is located between one of the bearings and the annular magnet. The limiting part includes a limiting body, a first limiting protrusion and a second limiting protrusion. The first limiting protrusion and the second limiting protrusion are provided on the limiting body. The second protrusion corresponds to the position of the first limiting protrusion and is oriented towards the annular magnet. The included angle formed by the two second protrusions is greater than the included angle formed by the arc-shaped portion.

2. The permanent magnet finite angle motor according to claim 1, characterized in that: The spring assembly includes a support, a return spring, and a fixing post. The support is connected to the housing. A plurality of first protrusions are provided at intervals on the side of the support facing away from the housing. One end of the return spring is connected to one of the first protrusions, and the other end of the return spring is elastically connected to the rotating shaft. The fixing post is provided on the rotating shaft, and the fixing post abuts against the return spring.

3. The permanent magnet finite angle motor according to claim 2, characterized in that: One end of the rotating shaft is provided with a groove. The return spring includes a bent portion and a straight portion provided at one end of the bent portion. The straight portion is connected to the bent portion and is located in the groove. The end of the bent portion away from the straight portion is provided with a bent portion. The bent portion is connected to the bent portion and is adapted to the first protrusion.

4. The permanent magnet finite angle motor according to claim 1, characterized in that: The frame includes two symmetrically arranged first frame bodies, each of which is provided with a first receiving groove and a second receiving groove. The first receiving groove and the second receiving groove are spaced apart. The two first receiving grooves are used to accommodate the iron core, and the two second receiving grooves are used to accommodate the coil.

5. The permanent magnet finite angle motor according to claim 1, characterized in that: The frame includes a second frame body, on which a first accommodating space is provided. The first accommodating space is used to accommodate the iron core. At opposite ends of the first accommodating space, a third accommodating groove is provided. The first accommodating space and the two third accommodating grooves are spaced apart. The two third accommodating grooves are used to accommodate the coil.

6. The permanent magnet finite angle motor according to claim 1, characterized in that: The angle between the two opposite ends of the iron core is 120°~160°.

7. The permanent magnet finite angle motor according to claim 1, characterized in that: The rotor assembly also includes an annular magnet protective ring, which is disposed between the annular magnet and the iron core.

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