A shock-absorbing and noise-reducing inner rotor and small micro direct-current brushless motor

Abstract

This invention proposes a vibration-damping and noise-reducing inner rotor and a miniature brushless DC motor, relating to the field of motors. It includes a coaxially mounted rotor structure and a magnetic ring. The rotor structure comprises a magnetic ring coupling part, a connecting part, and a power output part arranged sequentially along its axial direction. The magnetic ring coupling part is a cavity structure with one open end, and a magnetic ring mounting position is provided on its outer wall. The power output part has a through hole along the axial direction of the rotor structure. The inner wall of the connecting part is provided with a fixing claw part with three elastic claws extending towards the opening of the cavity structure. These claws form a fitting channel along the axial direction of the rotor structure that coincides with the central axis of the through hole, and the fitting channel includes at least one elastic clamping section configured as a straight cylindrical hole. When the rotor structure is mounted on the outer wall of the fixed shaft, the through hole and the outer wall of the fixed shaft are clearance-fitted, and the elastic clamping section tightly clamps the outer wall of the fixed shaft. The inner rotor proposed in this invention can effectively reduce vibration and lower motor operating noise.

Description

Technical Field

[0001] This invention relates to the field of motor technology, specifically to a shock-absorbing and noise-reducing inner rotor and a miniature brushless DC motor. Background Technology

[0002] The miniature internal rotor brushless DC motor integrates high power density design and electronic commutation technology, enabling the integration of a high-torque motor within a confined space of less than 60mm in diameter. In application, Hall effect sensors or back EMF are used to detect the rotor position in real time, and the current direction is dynamically adjusted by a controller to achieve contactless commutation. Compared to existing miniature motors, it not only effectively improves power density and heat dissipation efficiency but also significantly reduces noise and vibration, extending motor lifespan. Furthermore, the miniature internal rotor brushless DC motor uses rare-earth permanent magnet materials to increase the motor's magnetic field strength while reducing weight by more than 20%, further enhancing torque output. Based on the superior performance of the miniature internal rotor brushless DC motor, it has broad application prospects in precision robots, new energy vehicle auxiliary systems, and smart home devices.

[0003] The structure of the inner rotor not only affects the torque output of miniature internal rotor brushless DC motors, but also their safety and lifespan. Currently, most miniature internal rotor brushless DC motors on the market use a single spring combined with a clamping block for elastic clamping. This design only allows for unidirectional pre-tightening, making it difficult to guarantee rotor dynamic balance. Therefore, the larger the shaft hole clearance, the more severe the rotor runout. Abnormal operating noises, such as a "knocking" sound, can only be achieved when the total weight of the inner rotor is less than 5g, the single motor output torque is less than 0.5Nmm, and the shaft hole clearance is less than 0.02mm. Furthermore, the single spring combined with clamping block assembly method is costly, including higher material and material management costs, and higher assembly costs. It requires the procurement, quality control, and storage of additional clamping blocks and springs, as well as the purchase of automated pressing equipment for these components. During the inner rotor assembly process, there is also a risk of the clamping blocks and springs falling off. In addition, after the inner rotor is assembled inside the motor, the rotor will have a slight upward movement when the stator is powered on, and the installation state of the spring and pressure block will change slightly. It is also difficult to replace the inner rotor when the motor is pulled out. When the rotor is pulled out, the pressure block and spring will jump out and fall off.

[0004] Therefore, developing and designing a new, highly stable internal rotor structure can not only improve the torque output of a micro internal rotor brushless DC motor, but also enhance the motor's vibration and noise reduction performance, and reduce the motor's operating costs and safety hazards. Summary of the Invention

[0005] The purpose of this invention is to provide a shock-absorbing and noise-reducing inner rotor and a miniature brushless DC motor. The aim is to achieve multi-directional pre-tightening of the fixed shaft by improving the rotor structure, so that the inner rotor runs more smoothly. This not only effectively improves the shock-absorbing and noise-reducing performance of the motor, but also greatly reduces the manufacturing and usage costs.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: In the first aspect, a vibration-damping and noise-reducing inner rotor is proposed, which is suitable for a small and micro brushless DC motor in which the inner rotor rotates around a fixed shaft. It includes a rotor structure and a magnetic ring. The rotor structure is coaxially fitted onto the outer wall of the fixed shaft, and the magnetic ring is coaxially fitted onto the outer wall of the rotor structure. The rotor structure includes a magnetic ring coupling part, a connecting part, and a power output part arranged sequentially along its axial direction. The power output part is a gear. The magnetic ring coupling part is configured as a cavity structure away from the end opening of the power output part, and a magnetic ring mounting position is provided on its outer wall. The magnetic ring is adapted to be installed in the magnetic ring mounting position. The power output part is provided with a through hole for mounting a fixed shaft along the axial direction of the rotor structure. The through hole communicates with the interior of the magnetic ring coupling part, and the power output part is used to output the power provided by the rotation of the inner rotor. The connecting part transitionally connects the magnetic ring coupling part and the power output part. Its inner wall surface is provided with a fixing claw part extending towards the opening of the magnetic ring coupling part. The fixing claw part includes three elastic claws evenly arranged. The fixing claw part forms a fitting channel with both ends open along the axial direction of the rotor structure. The fitting channel extends from the end of the fixing claw part near the power output part to the end near the opening of the magnetic ring coupling part. The fitting channel coincides with the central axis of the through hole, and the fitting channel includes at least one elastic clamping section that is set as a straight cylindrical hole. When the rotor structure is fitted onto the outer wall of the fixed shaft through the through hole and the fitting channel, the through hole and the outer wall of the fixed shaft are in clearance fit, and the elastic clamping section tightly clamps the outer wall of the fixed shaft.

[0007] Furthermore, the fitting channel formed inside the fixed claw also includes a clearance fit section; The clearance fit section is located near the power output part and is configured as a straight cylindrical hole, and the diameter of the clearance fit section is equal to the diameter of the through hole; the elastic clamping section is located at the end of the clearance fit section away from the power output part and near the opening of the magnetic ring joint part, and its diameter is smaller than the diameter of the clearance fit section and smaller than the outer diameter of the fixed shaft.

[0008] Furthermore, the clearance fit section and the elastic clamping section are connected by an inverted conical hole transition.

[0009] Furthermore, the connection between the connecting part and the magnetic ring joint is configured as a planar connection, the fixing claw extends from the inner wall of the planar connection near the opening of the magnetic ring joint towards the opening direction, and the end of the fitting channel near the power output part is connected to the end of the through hole near the magnetic ring joint.

[0010] Furthermore, the inner wall surface of the fitting channel formed by the elastic claw is an arc-shaped surface, and the opening of the arc-shaped surface faces the central axis; when the elastic clamping segment tightly hugs the outer wall of the fixed shaft, the arc-shaped surface adheres to the outer wall of the fixed shaft.

[0011] Furthermore, let H be the height of the fixed claw along its axial direction and h be the height of the elastic clamping section on the fitting channel along its axial direction, then h = 1 / 3H ~ 2 / 3H.

[0012] Furthermore, the elastic claws of the fixed claw portion have the same structure and dimensions. The height of the elastic claw along the axial direction of the fixed claw portion is greater than three times the average claw wall thickness. The bending deformation deflection of any elastic claw is calculated as follows: y=(dD) / 2 ; in, y Indicates bending deformation deflection. d Indicates the outer diameter of the fixed shaft. D This indicates the diameter of the elastic clamping section, and y The maximum value does not cause the elastic claw to undergo plastic deformation.

[0013] Furthermore, the inner edge of the end claw opening near the opening of the magnetic ring joint is provided with a chamfer, the chamfer is at an angle of 15° to 30° with the axial direction of the fixed claw, and the diameter of the end claw opening after chamfering is larger than the outer diameter of the fixed shaft.

[0014] Furthermore, the rotor structure is integrally injection molded from an elastic plastic material, or the elastic claws and the rest of the rotor structure are molded using a two-color injection molding process with different plastic materials.

[0015] Secondly, a miniature brushless DC motor is proposed, characterized in that the miniature brushless DC motor adopts the above-mentioned shock-absorbing and noise-reducing inner rotor.

[0016] As can be seen from the above technical solutions, the technical solutions of the present invention have achieved the following beneficial effects: This invention discloses a vibration-damping and noise-reducing inner rotor and a miniature brushless DC motor. The inner rotor includes a rotor structure coaxially fitted onto the outer wall of a fixed shaft and a magnetic ring coaxially fitted onto the outer wall of the rotor structure. The rotor structure includes a magnetic ring coupling part, a connecting part, and a power output part arranged sequentially along its axial direction. The magnetic ring coupling part is configured as a cavity structure away from the opening of the power output part, and its outer wall is provided with a magnetic ring mounting position for fitting and installing the magnetic ring. The power output part is provided with a through hole for installing the fixed shaft along the axial direction of the rotor structure, and the through hole communicates with the interior of the magnetic ring coupling part. The inner wall surface of the connecting part is provided with a fixing claw part with three elastic claws extending towards the opening of the magnetic ring coupling part. The fixing claw part forms a fitting channel along the axial direction of the rotor structure that coincides with the central axis of the through hole, and the fitting channel includes at least one section of elastic clamping section configured as a straight cylindrical hole. When the rotor structure is fitted onto the outer wall of the fixed shaft, the through hole and the outer wall of the fixed shaft are clearance-fitted, and the elastic clamping section tightly clamps the outer wall of the fixed shaft. The inner rotor proposed in this invention uses elastic claws to elastically deform and fix the target object. When installed on a miniature brushless DC motor, it can achieve multi-directional elastic preload on the fixed shaft, thereby effectively reducing rotor yaw and vibration during motor operation, resulting in smoother rotor operation, reduced motor operating noise, and elimination of abnormal noise. Furthermore, the symmetrical structure of the inner rotor proposed in this invention makes it easier to maintain dynamic balance during rotation, thus reducing motor vibration and comprehensively improving the motor's vibration damping and noise reduction performance.

[0017] Furthermore, the internal rotor structure proposed in this invention eliminates the need for springs, pressure blocks, and other materials compared to existing technologies, thus saving material costs, management costs, and assembly costs. Moreover, due to the design of the internal rotor structure, its installation and replacement are relatively simple, and there is no need to worry about the springs or pressure blocks falling off or being lost, further reducing the repair and maintenance costs during the use of the motor.

[0018] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0019] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0020] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a three-dimensional structural diagram of the vibration-damping and noise-reducing inner rotor power output section disclosed in an embodiment of the present invention; Figure 2 This is a side view of the vibration-damping and noise-reducing inner rotor magnetic ring joint disclosed in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the vibration-damping and noise-reducing inner rotor structure disclosed in an embodiment of the present invention; Figure 4 for Figure 3 A magnified view of region A in the middle.

[0021] The specific meanings of each mark in the diagram are as follows: 1-Inner rotor; 11-Magnetic ring joint; 12-Connecting part; 13-Power output part; 131-Through hole; 14-Fixing claw part; 141-Elastic clamping section; 142-Clear fit section; 143-Elastic claw; 144-Chamfer; 15-Magnetic ring. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0023] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" mean that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0024] Currently, most micro-sized brushless DC motors on the market employ a single spring and pressure block-based vibration reduction and noise reduction scheme for their internal rotors. This scheme only allows for unidirectional pre-tightening of the fixed shaft, making it difficult to guarantee rotor dynamic balance. Therefore, the larger the shaft-hole clearance, the more severe the rotor runout. This method can only achieve noise-free operation, such as a "knocking" sound, when the total weight of the internal rotor is less than 5g, the single motor output torque is less than 0.5Nmm, and the shaft-hole clearance is less than 0.02mm. Furthermore, this scheme has high material, assembly, and maintenance costs. Therefore, this invention aims to propose a new vibration-damping and noise-reducing internal rotor. This structure is compact and easy to install and maintain, allowing for multi-directional elastic pre-tightening of the fixed shaft, effectively reducing rotor runout and vibration. This not only makes the rotor run more smoothly but also significantly reduces motor operating noise and eliminates abnormal noise.

[0025] Combination Figures 1 to 4 As shown, the present invention discloses a vibration-damping and noise-reducing inner rotor, which is suitable for a small and micro brushless DC motor in which the inner rotor rotates around a fixed shaft. It includes a rotor structure and a magnetic ring 15. The rotor structure is coaxially fitted onto the outer wall of the fixed shaft, and the magnetic ring 15 is coaxially fitted onto the outer wall of the rotor structure. As shown in the figure, the rotor structure includes a magnetic ring coupling part 11, a connecting part 12, and a power output part 13 arranged sequentially along its axial direction. In this embodiment, the power output part 13 is configured as a gear. The magnetic ring coupling part 11 is configured as a cavity structure with its opening away from the end of the power output part 13. A magnetic ring mounting position is provided on its outer wall, and the magnetic ring 15 is adapted to be installed in the magnetic ring mounting position. The power output part 13 is provided with a through hole 131 for mounting a fixed shaft along the axial direction of the rotor structure. The through hole 131 communicates with the interior of the magnetic ring coupling part 11, and the power output part 13 is used to output the power provided by the rotation of the inner rotor 1. The connecting portion 12 transitionally connects the magnetic ring coupling portion 11 and the power output portion 13, and its inner wall surface is provided with a fixing claw portion 14 extending towards the opening direction of the magnetic ring coupling portion 11, such as Figure 2 As shown, the fixing claw portion 14 includes three evenly arranged elastic claws 143; the fixing claw portion 14 forms a fitting channel with both ends open along the axial direction of the rotor structure, the fitting channel extends from the end of the fixing claw portion 14 near the power output portion 13 to the end near the opening of the magnetic ring coupling portion 11; the fitting channel coincides with the central axis of the through hole 131, and the fitting channel includes at least one elastic clamping section 141 configured as a straight cylindrical hole; Therefore, when the rotor structure is fitted onto the outer wall of the fixed shaft through the through hole 131 and the fitting channel, the through hole 131 and the outer wall of the fixed shaft are in clearance fit, and the elastic clamping section 141 tightly clamps the outer wall of the fixed shaft; wherein, the clearance between the through hole 131 and the shaft hole of the fixed shaft is 0.01mm~0.05mm, for example, if the outer diameter of the fixed shaft is 1.5mm, then the diameter of the through hole 131 is 1.51mm~1.55mm; the larger the clearance, the greater the risk of inner rotor yaw vibration noise. In the embodiment, to facilitate the pre-tightening of the fixed shaft by the elastic claw 143, the inner wall surface of the fixed claw portion 14 forming the fitting channel is an arc-shaped surface, and the opening of the arc-shaped surface faces the central axis; thus, when the elastic clamping section 141 tightly clamps the outer wall of the fixed shaft, the arc-shaped surface adheres to the outer wall of the fixed shaft.

[0026] Specific combination Figure 3 and Figure 4 As shown, the magnetic ring coupling portion 11 has flanges on its outer periphery at both ends along its axial direction, and the flanges extend away from its central axis. The flange of the magnetic ring coupling portion 11 near the end of the connecting portion 12 is defined as the first flange and the flange away from the end of the connecting portion 12 is defined as the second flange. The sidewalls of the first flange and the second flange that are close to each other and the part of the outer wall of the magnetic ring coupling portion 11 located between the two flanges constitute the magnetic ring mounting position. The magnetic ring 15 is adapted to be embedded in the magnetic ring mounting position.

[0027] Further integration Figure 3 and Figure 4In the illustrated embodiment, the fitting channel formed inside the fixed claw portion 14 further includes a clearance fit section 142; the clearance fit section 142 is located near the power output portion 13, is configured as a straight cylindrical hole, and the diameter of the clearance fit section 142 is equal to the diameter of the through hole 131; the elastic clamping section 141 is located at the end of the clearance fit section 142 away from the power output portion 13, near the opening of the magnetic ring coupling portion 11, and its diameter is smaller than the diameter of the clearance fit section 142 and smaller than the outer diameter of the fixed shaft; as shown in the figure, in the design, the clearance fit section 142 and the elastic clamping section 141 are connected by an inverted conical hole transition connection. In the embodiment, the connection between the magnetic ring coupling portion 11 and the connecting portion 12 is configured as a planar connection, the fixed claw portion 14 extends from the inner wall of the planar connection near the opening of the magnetic ring coupling portion 11 towards the opening direction, and the end of the clearance fit section 142 of the fitting channel near the power output portion 13 is connected to the end of the through hole 131 near the magnetic ring coupling portion 11.

[0028] In addition, during the design, the lengths of the clearance fit section 142 and the elastic clamping section 141 must be set to ensure the pre-tightening effect of the fixed claw 14, meet the requirements of the initial elastic clamping force, and ensure the dynamic balance of the inner rotor 1 when it rotates on the fixed shaft; that is, the height of the fixed claw 14 along its axial direction is defined as H, and the height of the elastic clamping section 141 on the fitting channel along its axial direction is defined as h, then h = 1 / 3H ~ 2 / 3H.

[0029] Furthermore, to ensure the service life of the elastic claw 143, the design must also consider the size, thickness, and bending deflection of the elastic claw 143 to ensure that no plastic deformation occurs when the elastic claw 143 is interference-fitted with the fixed shaft. Specifically, the structure and dimensions of each elastic claw 143 in the fixed claw portion 14 are the same, the height of the elastic claw 143 along the axial direction of the fixed claw portion 14 is greater than three times the average claw wall thickness of the elastic claw 143, and the bending deflection of any elastic claw 143 is calculated as follows: y=(dD) / 2 ; in, y Indicates bending deformation deflection. d Indicates the outer diameter of the fixed shaft. D This indicates the diameter of the elastic clamping section, and y The maximum value does not cause the elastic claw 143 to undergo plastic deformation.

[0030] A simplified way to calculate the bending deformation deflection y of the elastic claw 143 is to simplify the elastic claw 143 into a cantilever beam and calculate it according to the deflection calculation formula for cantilever beams in mechanics of materials: y = (FL³) / (3EI) ; in, FThis refers to the force exerted by a single elastic gripper on a fixed shaft, also known as the shaft gripping force. L This indicates the minimum axial distance between the contact position between the elastic clamping section 141 and the outer diameter of the fixed shaft and the root of the elastic claw. E This represents the elastic modulus of the material of elastic claw 143. I The moment of inertia represents the cross-section of the elastic claw 143; Therefore, the clamping force of the single elastic claw 143 is... F The calculation formula is as follows: F=3yEI / L³ ; Among them, elastic modulus E The elasticity of the claw 143 is related to the material used; for example, PA9T has an elastic modulus of 2.3 GPa and a moment of inertia. I The cross-sectional shape of the elastic claw 143 is related to the calculation formula, which is as follows: I=∫x²dA ; Moment of inertia I The calculation formula is defined as the area of ​​each infinitesimal element of the cross-section of the elastic claw 143. dA Distance from the infinitesimal element to the specified axis x The integral of the square of.

[0031] The bending deformation deflection of the aforementioned elastic claw 143 y The calculation process is only applicable to rough calculations; fine calculations require CAE simulation of real-world scenarios.

[0032] Typically, the fixed shaft passes axially through the rotor structure from the fixed claw portion 14. In this embodiment, to facilitate the installation of the fixed shaft, such as... Figure 4 As shown, the inner edge of the end claw opening of the fixed claw portion 14 near the opening of the magnetic ring coupling portion 11 is provided with a chamfer 144. The angle between the chamfer 144 and the axial direction of the fixed claw portion 14 is 15°~30°, and the diameter of the end claw opening after the chamfer 144 is larger than the outer diameter of the fixed shaft, which facilitates the insertion of the fixed shaft. In the embodiment, the angle between the chamfer 144 and the axial direction of the fixed claw portion 14 is 20°.

[0033] In the embodiments, the rotor structure of the inner rotor is integrally injection molded from an elastic plastic material, such as wear-resistant and self-lubricating plastic materials like POM, PEEK, and PA9T. Within the operating temperature range, the dimensions are relatively stable and not prone to plastic deformation. In some embodiments, the rotor structure is molded using a two-color injection molding process with different plastic materials for the elastic claw 143 and other parts of the rotor structure, depending on actual needs. The elastic claw 143 still needs to be made of an elastic plastic material.

[0034] Therefore, the vibration-damping and noise-reducing inner rotor disclosed in this invention can be prepared by the following three processes respectively; Process 1: Using overmolded injection molding, the magnetic ring 15, made of adhesive magnet or injection-molded magnet, is placed into the injection mold and then injection molded; wherein, the injection mold is a mold made in advance according to the designed inner rotor structure; this process has moderate efficiency in preparing vibration-damping and noise-reducing inner rotors and can be used for inner rotor 1 in mass production schemes; Process 2: Two-color injection molding is adopted, in which the magnetic ring 15 is injection molded magnetically, and both the magnetic ring 15 and the rotor structure are injection molded; This process is highly efficient in preparing the vibration-damping and noise-reducing inner rotor and is more suitable for the inner rotor 1 in mass production schemes; Process 3: The rotor structure is formed by CNC machining and then assembled with the magnetic ring 15 to form a vibration-damping and noise-reducing inner rotor. Since CNC machining takes a long time, this process is generally used for small-batch sample production.

[0035] In practice, a suitable process scheme is selected based on the requirements for the performance and weight of the magnetic ring 15, as well as the production cycle and cost of the inner rotor.

[0036] The vibration-damping and noise-reducing inner rotor disclosed in this invention allows the fixed shaft to smoothly enter the fitting channel through the bending deformation of the elastic claws 143. Upon reaching the target position, the three elastic claws 143 provide a clamping force to movably connect the inner rotor 1 to the fixed shaft. Simultaneously, the deformation caused by the bending of the elastic claws 143 reduces or offsets the swaying and vibration of the inner rotor 1 during operation, thereby reducing the operating noise of the brushless motor or eliminating abnormal noise, such as the clicking sound emitted when the inner rotor 1 sways and strikes the fixed shaft. Furthermore, compared to existing technologies, the simplified structure effectively saves production and maintenance costs and is more convenient to use.

[0037] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A vibration-damping and noise-reducing inner rotor, characterized in that, A miniature brushless DC motor suitable for internal rotor rotating around a fixed shaft, comprising a rotor structure and a magnetic ring, wherein the rotor structure is coaxially fitted onto the outer wall of the fixed shaft, and the magnetic ring is coaxially fitted onto the outer wall of the rotor structure; The rotor structure includes a magnetic ring coupling part, a connecting part, and a power output part arranged sequentially along its axial direction. The power output part is a gear. The magnetic ring coupling part is configured as a cavity structure away from the end opening of the power output part, and a magnetic ring mounting position is provided on its outer wall. The magnetic ring is adapted to be installed in the magnetic ring mounting position. The power output part is provided with a through hole for mounting a fixed shaft along the axial direction of the rotor structure. The through hole communicates with the interior of the magnetic ring coupling part, and the power output part is used to output the power provided by the rotation of the inner rotor. The connecting part transitionally connects the magnetic ring coupling part and the power output part. Its inner wall surface is provided with a fixing claw part extending towards the opening of the magnetic ring coupling part. The fixing claw part includes three elastic claws evenly arranged. The fixing claw part forms a fitting channel with both ends open along the axial direction of the rotor structure. The fitting channel extends from the end of the fixing claw part near the power output part to the end near the opening of the magnetic ring coupling part. The fitting channel coincides with the central axis of the through hole, and the fitting channel includes at least one elastic clamping section that is set as a straight cylindrical hole. When the rotor structure is fitted onto the outer wall of the fixed shaft through the through hole and the fitting channel, the through hole and the outer wall of the fixed shaft are in clearance fit, and the elastic clamping section tightly clamps the outer wall of the fixed shaft.

2. The vibration-damping and noise-reducing inner rotor according to claim 1, characterized in that, The fitting channel formed inside the fixed claw portion further includes a clearance fit section; The clearance fit section is located near the power output part and is configured as a straight cylindrical hole, and the diameter of the clearance fit section is equal to the diameter of the through hole; the elastic clamping section is located at the end of the clearance fit section away from the power output part and near the opening of the magnetic ring joint part, and its diameter is smaller than the diameter of the clearance fit section and smaller than the outer diameter of the fixed shaft.

3. The vibration-damping and noise-reducing inner rotor according to claim 2, characterized in that, The clearance fit section and the elastic clamping section are connected by an inverted conical hole transition.

4. The vibration-damping and noise-reducing inner rotor according to claim 2, characterized in that, The connection between the connecting part and the magnetic ring joint is configured as a planar connection. The fixing claw extends from the inner wall of the planar connection near the opening of the magnetic ring joint towards the opening direction. The end of the fitting channel with clearance fitting near the power output part is connected to the end of the through hole near the magnetic ring joint.

5. The vibration-damping and noise-reducing inner rotor according to claim 1, characterized in that, The inner wall surface of the fitting channel formed by the elastic claw is an arc-shaped surface, and the opening of the arc-shaped surface faces the central axis. When the elastic clamping section tightly hugs the outer wall of the fixed shaft, the arc-shaped surface fits against the outer wall of the fixed shaft.

6. The vibration-damping and noise-reducing inner rotor according to claim 3, characterized in that, Let H be the height of the fixed claw along its axial direction and h be the height of the elastic clamping section along its axial direction on the fitting channel. Then h = 1 / 3H ~ 2 / 3H.

7. The vibration-damping and noise-reducing inner rotor according to claim 2, characterized in that, The elastic claws of the fixed claw portion have the same structure and dimensions. The height of the elastic claw along the axial direction of the fixed claw portion is greater than 3 times the average claw wall thickness. The bending deformation deflection of any elastic claw is calculated as follows: y=(dD) / 2 ； in, y Indicates bending deformation deflection. d Indicates the outer diameter of the fixed shaft. D This indicates the diameter of the elastic clamping section, and y The maximum value does not cause the elastic claw to undergo plastic deformation.

8. The vibration-damping and noise-reducing inner rotor according to claim 2, characterized in that, The inner edge of the end claw opening near the opening of the magnetic ring joint is provided with a chamfer. The chamfer makes an angle of 15° to 30° with the axial direction of the fixed claw, and the diameter of the end claw opening after chamfering is larger than the outer diameter of the fixed shaft.

9. The vibration-damping and noise-reducing inner rotor according to claim 1, characterized in that, The rotor structure is integrally injection molded from an elastic plastic material, or the elastic claws and the rest of the rotor structure are molded using a two-color injection molding process with different plastic materials.

10. A miniature brushless DC motor, characterized in that, The miniature brushless DC motor adopts the vibration-damping and noise-reducing inner rotor as described in any one of claims 1-9.

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