Shaft hole matching structure of brushless motor rotor

Abstract

The invention discloses a shaft hole matching structure of a brushless motor rotor. The shaft hole matching structure comprises a rotor main body, magnetic steel attached to the outside of the rotor main body, and a shaft body matched on the axis of the rotor main body, the rotor main body comprises a framework part for supporting magnetic steel and a shaft seat part for inserting a shaft body, the framework part is arranged in a hollow manner and is connected to the outer wall of the shaft seat part, and the shaft seat part defines a shaft tensioning structure and a rotor transmission structure on the two sides of the connecting part of the framework part; the shaft tensioning structure extends to the hollow inner side of the framework part, the shaft tensioning structure comprises a plurality of petal-shaped bodies which are arranged around the axis at intervals, the petal-shaped bodies elastically enclasp the shaft body and limit the radial movement of the rotor main body relative to the shaft body, and the radial movement and collision noise in the rotating process of the rotor are effectively eliminated.

Description

Technical Field

[0001] This invention relates to the field of motor component technology, specifically to a shaft hole fitting structure for a brushless motor rotor. Background Technology

[0002] Currently, a brushless motor rotor typically includes a central shaft hole, a base shaft passing through the central shaft hole, and a rotor body. The rotor body is equipped with magnets. In the mating state, the base shaft and the central shaft hole are fitted with a clearance fit, allowing the rotor body to rotate relative to the base shaft. However, due to the clearance fit between the base shaft and the central shaft hole, if the clearance is too small, it will affect the smoothness of rotation; if the clearance is too large, there will be collision noise between the outer wall of the base shaft and the inner wall of the central shaft hole during rotation, affecting normal use.

[0003] Typically, brushless motor rotors in existing technologies usually have bearings at both ends of a fixed base shaft to improve stability during rotation. However, this traditional method undoubtedly increases assembly difficulty and overall cost. In the prior art, Chinese utility model patent with publication number CN219592223U, in order to ensure the matching degree of the steel shaft and gear hole, a split insert is set in the gear. The insert is supported by a spring and forms part of the shaft hole of the steel shaft. The spring provides corresponding compensation for the machining error. Although it can improve the fit of the steel shaft and gear, there is still wobble between the steel shaft and the rotor body during high-speed movement. At this time, the spring and the insert will repeatedly collide with the steel shaft under the wobble, generating abnormal noise. In addition, the extra insert and spring increase the assembly steps, which is not conducive to automated assembly. At the same time, a limiting end cap needs to be set on one side of the rotor body to prevent the insert from axially dislodging. However, this layout leads to the increase of independent parts, and the assembly of the magnet also depends on the cooperation between the rotor body and the limiting end cap, which will also affect the stability of the magnet on the rotor body to a certain extent. In another prior art publication, CN211151651U, the axial displacement of the rotor magnet assembly is limited by fixing spring elements and ring elements at both ends of the rotor magnet assembly. The spring elements are fixed to the rotor magnet assembly via a press-fit. While this method controls the axial displacement of the rotor magnet assembly through the spring element's clamping action, and the plastic ring element is fixed to the shaft, the different materials and mating positions of the elastic and ring elements make their design difficult to calculate, necessitating the use of an intermediate connecting element. On one hand, the connecting element effectively separates the spring and ring elements to reduce their linkage; thus, the connecting element is a necessary design element. However, this results in excessive axial space occupied by the fixing device on the rotor body. Furthermore, the connecting element... The space separated from the shaft needs to be filled and supported by bearings; otherwise, the space will cause instability in the rotor's operation. That is, the press-fit connection between the independent fixing device and the aforementioned bearing components will increase the assembly difficulty. On the other hand, the fixing device actually transmits torque through the frictional fit between the ring element and the shaft, and the frictional fit between the spring element and the rotor magnet assembly through axial pressure. The spring element relies on the fixing of the ring element on the shaft to achieve the compression posture. In other words, the rotor magnet assembly and the shaft do not directly contact each other, which is not suitable for brushless motor applications. At the same time, although the fixing device is fixed to the shaft radially, the fixing device is independent of the rotor magnet assembly. When radial yaw occurs, the spring elements at both ends will be pulled and yawed by the rotor magnet assembly. Without the bearing components at both ends to further hold it, the radial yaw problem cannot be solved well. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a shaft hole mating structure for a brushless motor rotor.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A shaft-hole mating structure for a brushless motor rotor includes: The rotor body, the magnets attached to the outside of the rotor body, and the shaft that fits on the axis of the rotor body; The rotor body includes a skeleton portion supporting the magnets and a bearing portion for inserting the shaft. The skeleton portion is hollow and connected to the outer wall of the bearing portion. The bearing portion defines a shaft tensioning structure and a rotor transmission structure on both sides of the connection point of the skeleton portion. The shaft tensioning structure extends into the hollow inner side of the skeleton portion and includes a plurality of petal-shaped bodies spaced around the axis. The petal-shaped bodies elastically hold the shaft and restrict the radial movement of the rotor body relative to the shaft.

[0006] Furthermore, the connecting portion connects the skeleton portion and the bearing portion in the radial direction and forms the axial end of the rotor body. The petal-shaped body includes a root portion formed on the connecting portion and an elastic arm extending from the root portion away from the rotor drive structure.

[0007] Furthermore, the elastic arm includes a clamping curved surface that fits on the outer wall of the shaft body. The clamping curved surface includes at least a clamping section that protrudes radially toward the axis and a retractable section that extends axially to the clamping section. The plurality of the petals control the dynamic clearance of the rotor body relative to the shaft body through the clamping section. The retractable section is at least connected to the connecting part and provides a clamping surface that fits with the shaft body.

[0008] Furthermore, the petal-shaped body includes an initial pose detached from the shaft and an assembly pose mating with the shaft; In the initial position, the clamping section protrudes near the axis relative to the retracting section. In the assembly position, the clamping section is abutted and expanded by the shaft, and the retracting section is at least partially clamped to the shaft.

[0009] Furthermore, in the initial position, the retracting section is inclined radially inward from the root along the axial direction and connects to the clamping section, and the back of the elastic arm is set as a vertical curve parallel to the axis.

[0010] Furthermore, the retractable section is connected between the clamping section and the connecting part, and the clamping surface expands from the clamping section toward the retractable section, and the clamping surface forms the minimum clamping surface on the clamping section.

[0011] Furthermore, the rotor drive structure is configured to extend axially away from the frame portion from the connecting part, so that the center of gravity of the rotor body is offset along the axis toward the connecting part.

[0012] Furthermore, the elastic arm has a guide opening on its open side, and the guide opening forms the maximum clamping surface.

[0013] Furthermore, the frame portion has support portions on both sides of the shaft end, the magnet is sleeved on the frame portion and abuts against the support portions, and the magnet and the support portions have a concave-convex fit structure.

[0014] Furthermore, a material stacking area is provided between the root of the elastic arm and the connecting part.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention solves the problems of collision noise caused by excessive clearance and smooth rotation caused by insufficient clearance in traditional clearance fits. By arranging elastic petal-shaped bodies around the rotation axis, the petal-shaped bodies provide reliable support and elastic clamping for the shaft inserted into the rotor body, and the shaft provides reference support on the bearing portion on the other side of the axis. When a deviation occurs on the rotation axis between the rotor body and the rotating shaft, the deviation transmission will be suppressed by the elastic clamping action of the petal-shaped bodies. In the assembled state, after the shaft is inserted, the petal-shaped body automatically adapts to the shaft diameter and dynamically adjusts the fitting clearance, effectively eliminating radial movement and collision noise during rotor rotation, while ensuring smooth rotation and effectively reducing speed fluctuations. The elastic design of the flaps allows them to compensate for manufacturing errors, thermal expansion, and wear in the shaft and rotor body bores, maintaining long-term stable fit accuracy. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the rotor body and shaft assembly position of the present invention; Figure 3 This is a front view of the valve body of the present invention; Figure 4 This is a schematic diagram of the rotor body of the present invention; Figure 5 This is an exploded view of the rotor body and magnets of the present invention; Figure 6 This is an exploded view of the rotor body and magnets from another angle according to the present invention; Figure 7 This is a cross-sectional view of the rotor body of the present invention; Figure 8 This is a schematic diagram of the structure of the elastic arm of the present invention; Figure 9 This is a cross-sectional schematic diagram of the elastic arm of the present invention; In the diagram: 1. Rotor body; 11. Frame part; 12. Shaft seat part; 13. Connection part; 14. Support part; 2. Magnet; 3. Shaft; 4. Shaft tensioning structure; 41. Elastic arm; 42. Root; 421. Material stacking part; 43. Clamping section; 44. Retracting section; 45. Clamping curved surface; 5. Rotor transmission structure; 6. Guide opening; 7. Concave-convex mating structure; 71. Ring body; 72. Protrusion; 73. Contour body. Detailed Implementation

[0017] 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 embodiments of the present invention, and not all embodiments. 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.

[0018] It should be understood that although the terms upper, middle, lower, top, one end, etc., appear in this document to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish the elements from each other for ease of understanding, and are not used to define any directional or sequential restrictions.

[0019] like Figure 1-9 As shown, a shaft hole fitting structure for a brushless motor rotor includes: The rotor body 1, the magnet 2 attached to the outside of the rotor body 1, and the shaft 3 that is fitted on the axis of the rotor body 1; The rotor body 1 includes a skeleton portion 11 supporting the magnet 2 and a bearing portion 12 for inserting the shaft 3. The skeleton portion 11 is hollow and connected to the outer wall of the bearing portion 12. The skeleton portion 11 is an annular body 71. The magnet 2 is arranged on the outer wall of the skeleton portion 11. The bearing portion 12 extends along the axis of the rotor body 1. The bearing portion 12 defines a shaft tensioning structure 4 and a rotor transmission structure 5 on both sides of the connection portion 13 of the skeleton portion 11. The inner diameter of the skeleton portion 11 is larger than the outer diameter of the bearing portion 12. The connection portion 13 refers to the position where the outer wall of the bearing portion 12 connects to the inner wall of the skeleton portion 11. In the axial direction, the shaft tensioning structure 4 and the rotor transmission structure 5 extend axially opposite each other. Preferably, the shaft tensioning structure 4 extends inside the hollow skeleton portion 11. The shaft tensioning structure 4 specifically includes a plurality of petal-shaped bodies spaced apart around the axis. The petal-shaped bodies are arranged in an annular pattern and elastically clamp together. The rotor body 1 is placed on the shaft 3 and its radial movement is restricted relative to the shaft 3. The inner surface of the petal-shaped body forms an arc-shaped structure that matches the outer wall of the shaft 3. The inner surface of the petal-shaped body defines a first hole area for the shaft 3 to pass through. The inner surface of the bearing portion 12 defines a second hole area that is axially connected to the first hole area. The minimum inner diameter of the first hole area is smaller than the outer diameter of the shaft 3, so that the petal-shaped body is pressed against the shaft 3 under the insertion action, thereby applying an elastic clamping force to the shaft 3. The second hole area preferably forms a clearance fit with the shaft 3. The first hole area and the second hole area together form a shaft hole structure. The first hole area forms an open opening through the free end side of the petal-shaped body for the shaft 3 to be inserted. In this embodiment, the first hole area is used as the reference fit for the shaft 3. During the rotation of the rotor, the clearance between the rotor body 1 and the shaft 3 is dynamically adjusted by the second hole area so that the rotor body 1 rotates around the axis of the shaft 3.

[0020] In some embodiments, the shaft tensioning structure 4 preferably extends axially from the connecting portion 13 away from the rotor drive structure 5 and is close to the axial side end of the skeleton portion 11 away from the connecting portion 13. Of course, the shaft tensioning structure 4 can also extend axially outside the skeleton portion 11 to further optimize the holding effect of the petal on the shaft 3. In contrast, the rotor drive structure 5, as the application part for torque transmission, extends axially from the connecting portion 13 to the skeleton portion 11 in at least part, thus forming an axial misalignment between the skeleton portion 11 and the shaft seat portion 12. The first hole region is located in the skeleton portion 11. The radial sway generated in the working state of the rotor body 1 is controlled by the petal that elastically hugs the shaft 3, ensuring the concentricity of the first hole region and the second hole region relative to the shaft 3.

[0021] like Figure 2 and Figure 7 As shown, as a further embodiment of the petal-like body on the connecting portion 13, the connecting portion 13 connects the skeleton portion 11 and the bearing portion 12 in the radial direction and forms the axial end of the rotor body 1. The connecting portion 13 specifically forms the axial end sidewall of the skeleton portion 11. The petal-like body includes a root portion 42 formed on the connecting portion 13 and an elastic arm 41 extending from the root portion 42 away from the rotor transmission structure 5. The elastic arm 41 specifically extends axially on the hollow side of the skeleton portion 11. Multiple elastic arms 41 are spaced apart from each other in the circumferential direction to provide a clearance for the movement of the elastic arms 41. The connecting portion 13, as the connection hub between the skeleton and the bearing, provides a stable foundation for the petal-like body and ensures the uniformity of the force on the elastic arm 41. The integrated design of the root portion 42 and the connecting portion 13 enhances the structural strength and avoids stress concentration. The extension direction of the elastic arm 41 optimizes the transmission path of the clamping force, improves the reliability and fatigue life of the system, and the minimum inner diameter of the elastic arm 41 is arranged on the side away from the root portion 42. The constraint parts of the first hole area and the second hole area on the shaft 3 are arranged at both ends of the rotor body 1 to better control the radial runout of the rotor body 1 relative to the shaft 3.

[0022] As an example, there are three elastic arms 41, which are spaced apart around the axis. When the motor is running, the rotor body 1 is affected by radial electromagnetic force, load changes or slight dynamic imbalance, causing the axis to shift momentarily. At this time, the shaft 3 will slightly squeeze or loosen the clamping section 43 on one side. The elastic deformation of the petal on the squeezed side increases, the clamping force increases instantaneously, and a reverse support force is generated, pushing the rotor body 1 back to the center position. The elastic deformation of the petal on the loosened side decreases, and the clamping force weakens accordingly. This achieves dynamic and elastic concentricity maintenance, effectively suppressing radial movement and the resulting collision noise.

[0023] The rotor drive structure 5 is configured as a gear. In some embodiments, the outer diameter of the elastic arm 41 is configured to match the root circle diameter of the gear to improve the structural consistency of the bearing portion 12.

[0024] Further reference Figure 2 , Figure 4 and Figures 8 to 9 As shown, the elastic arm 41 includes a clamping curved surface 45 that fits on the outer wall of the shaft 3. On both sides of the clamping curved surface 45 of each elastic arm 41, there are inclined base surfaces that expand outward in the radial direction. The inclined base surfaces on both sides connect from the clamping area surface 45 to the back of the elastic arm 41, and the inclined base surfaces connect axially to the root 42 of the elastic arm 41. The clamping curved surface 45 is preferably an arc surface that fits with the outer wall of the shaft 3 so that the elastic arm 41 and the shaft 3 are fully fitted.

[0025] In this embodiment, the clamping surface 45 is configured to provide elastic contact and clamping force to the shaft 3. It releases the shaft hole in the first hole area by inserting the shaft 3 between the petals and applies clamping force to the shaft 3. The clamping surface 45 includes at least a clamping section 43 that protrudes radially toward the axis and a retractable section 44 that extends on the axial side of the clamping section 43. The multiple petals control the dynamic clearance of the shaft 3 through the clamping section 43. The retractable section 44 is at least connected to the connecting part 13 and provides a clamping surface that mates with the shaft 3. The radial protrusion of the clamping section 43 causes the clamping force to be applied to the part of the shaft 3 inside the rotor body 1, effectively suppressing radial movement and realizing clearance control between the rotor body 1 and the shaft 3.

[0026] Specifically, the flap includes the initial pose detached from the shaft 3, and the assembly pose mating with the shaft 3; In the initial position, the clamping section 43 protrudes close to the axis relative to the retracting section 44. In the assembly position, the clamping section 43 is abutted and expanded by the shaft 3, and the retracting section 44 is at least partially clamped to the shaft 3.

[0027] In other words, in the initial position, the petal is in a pre-tightened state, and the radial clamping force is provided by the expansion of the petal. Specifically, it is controlled by the outer diameter of the shaft 3 and the minimum inner diameter defined by the clamping section 43 of the petal in the initial position, so that the pre-tightened state of the initial position allows the shaft 3 to be easily inserted; the adaptive expansion of the assembly position ensures that the clamping force is dynamically adjusted with the position of the shaft 3, and compensates for eccentricity or offset in real time, so that the rotor body 1 is always automatically aligned with the axis, improving the rotational balance.

[0028] Further reference Figure 8 and Figure 9As shown, as a further embodiment of the retractable section 44, in its initial position, the retractable section 44 is inclined radially inward from the root 42 along the axial direction and connects to the clamping section 43, thereby creating a radial distance between the clamping section 43 and the axis during the stroke from the root 42, and this radial distance expands toward the root 42. On the one hand, this arrangement provides a reliable elastic clamping force for the clamping section 43 after expansion. On the other hand, for the assembly position after the shaft 3 is inserted, the clamping section 43 adaptably moves radially outward, so that the retractable section 44, which is inclined in the initial position, tends to fit against the outer wall of the shaft 3, and further clamps onto the shaft 3 through the retractable section 44 with a larger axial span, thereby realizing the dynamic gap adjustment between the shaft 3 and the rotor body 1 by the entire elastic arm 41.

[0029] Preferably, the back of the elastic arm 41 is set as a vertical curve parallel to the axis. The purpose is to control the wall thickness of the elastic arm 41, that is, the clamping section 43 has the maximum wall thickness, while the retracting section 44 has a smaller wall thickness near the root 42. This allows the elastic arm 41 to expand better when the shaft 3 is inserted to apply clamping force. In addition, this arrangement allows the clamping section 43 to apply the maximum clamping force, so that the clamping effect of the shaft 3 is more uniform in the axial direction of the elastic arm 41. During rotation, it can also reduce the friction between the elastic arm 41 and the shaft 3 that is not conducive to the smooth rotation of the rotor body 1.

[0030] In the above embodiments, the retracting section 44 has different assembly positions depending on the outer diameter of the shaft 3. Those skilled in the art can conceive of designing a shaft 3 with a reasonable outer diameter or a reliable wall thickness based on the above embodiments, so that the rotor body 1 can rotate smoothly and reliably on the shaft 3. At the most basic level, the outer diameter of the shaft 3 is at least greater than the minimum inner diameter of the clamping section 43.

[0031] For example, if the outer diameter of the shaft 3 is smaller than the maximum inner diameter defined by the retracting section 44, the retracting section 44 is partially clamped to the shaft 3 in the assembly position. If the outer diameter of the shaft 3 is larger than the maximum inner diameter defined by the retracting section 44, the retracting section 44 is fully clamped to the shaft 3 in the assembly position. It can be seen that the elastic petal-shaped body can adapt to shafts 3 with different outer diameters to improve the adaptability of the shaft 3. In any of the above cases, the clamping section 43 can apply an elastic clamping force to the shaft 3, which relatively reduces the design difficulty. At the same time, the petal-shaped body is integrally formed on the connecting part 13, which eliminates the need for additional assembly work and improves the assembly efficiency of the brushless motor. During the assembly process, it is only necessary to insert the rotor, which is configured as a whole, into the shaft 3.

[0032] As a further improvement to the clamping surface 45, it is preferable to apply a reliable clamping force to cope with different axial positions. The retractable section 44 is connected between the clamping section 43 and the connecting part 13. The clamping surface expands from the clamping section 43 toward the retractable section 44. The clamping surface forms the minimum clamping surface on the clamping section 43. The expansion design of the clamping surface increases the contact area with the shaft 3, distributes the clamping stress, and prevents the plastic deformation of the petal-shaped body caused by stress concentration. Especially during the installation of the shaft 3, the outer wall of the shaft 3 abuts against the clamping section 43, causing the petal-shaped body to expand. At this time, the outer wall of the shaft 3 and the expanded retractable section 44 fully cooperate to further improve the control of the sway of the shaft 3 and the concentricity of the shaft 3 and the rotor body 1.

[0033] It should be noted that the expanded clamping surface also improves the adaptability to the shaft 3. At least the clamping section 43 of the smallest clamping surface can apply a reliable clamping force to the shaft 3. Depending on the outer diameter of the shaft 3, the larger the outer diameter of the shaft 3, the larger the contact area between the shaft 3 and the elastic arm 41, until the shaft 3 is fitted to the position of the elastic arm 41 near the root 42. At this time, the radial expansion deformation of the elastic arm 41 is also greater. For the shaft 3 with a larger outer diameter, a more reliable clamping force is required. Therefore, the clamping surface is designed to expand near the root 42, thereby optimizing the reliability of the fit between the rotor body 1 and the shaft 3.

[0034] Specifically, the rotor drive structure 5 is configured to extend axially away from the frame portion 11 from the connecting part 13. The rotor drive structure 5 extends out of the rotor body 1 along the axis to control the center of gravity of the rotor body 1 to shift towards the connecting part 13 along the axis, thereby reducing the inertial torque when the rotor body 1 rotates, improving the dynamic balance performance, and reducing vibration and noise. At the same time, since the center of gravity is shifted away from the shaft tensioning structure 4, the elastic deformation of the petal-shaped body is more controllable, improving the compensation sensitivity for the eccentricity of the shaft body 3 and ensuring stability under high-speed rotation.

[0035] Based on this, the root 42 of the elastic arm 41 is arranged on the connecting part 13, relatively close to the center of gravity of the rotor body 1. That is, the rotor transmission structure 5 is configured at one end of the center of gravity for balance, and the clamping force of the clamping section 43 is configured at the other end of the center of gravity to provide reliable dynamic balance. The root 42, which is thicker than the wall thickness of the clamping section 43 and the retracting section 44, is set at the position close to the center of gravity to further improve the dynamic balance at the connecting part 13 and the retracting force of the elastic arm 41 on the shaft 3.

[0036] Specifically, a material stacking portion 421 is provided between the root 42 of the elastic arm 41 and the connecting portion 13. The material stacking portion 421 specifically refers to the arc-shaped portion formed on the root 42 of the elastic arm 41. This arc-shaped portion expands outward from the back of the root 42 of the elastic arm 41 towards the periphery. Its purpose is to increase the material thickness in the root 42 region, significantly improve the fatigue strength of the petal, and avoid the risk of fracture under repeated elastic deformation. The material stacking also optimizes the stress distribution. Importantly, the material stacking portion 421 provides a reliable reset action for the petal to ensure the elastic clamping effect of the petal on the shaft 3.

[0037] In other embodiments, to further improve assembly efficiency, the elastic arm 41 is provided with a guide opening 6 on the open side. The guide openings 6 of multiple elastic arms 41 form a guide opening at the axial end. The guide opening 6 forms a maximum clamping surface, and the maximum inner diameter defined by the guide opening 6 is greater than the maximum inner diameter defined by the retracting section 44, so that the shaft 3 can be quickly aligned and inserted during assembly, reducing the assembly error rate. The opening structure also allows easy inspection of the petal condition during maintenance, improving maintainability.

[0038] like Figure 5 and Figure 6 As shown, as a further embodiment of the cooperation between the magnet 2 and the rotor body 1, the frame portion 11 has support portions 14 on both sides of the shaft end. The magnet 2 is sleeved on the frame portion and abuts against the support portions 14. A concave-convex fitting structure 7 is provided between the magnet 2 and the support portions 14. The support portions 14 and the concave-convex fitting structure 7 ensure that the magnet 2 is fixed in the circumferential and axial directions on the rotor body 1, preventing the magnet 2 from loosening or shifting under high-speed rotation.

[0039] Preferably, the magnet 2 is a regular circular ring shape to control the rotor's center of gravity to be on the axis.

[0040] Specifically, the support portion 14 is disposed at the outer edge of the frame portion 11 and expands radially at the outer edge. The concave-convex fitting structure 7 on the frame portion 11 is specifically disposed on the opposite sides of the two support portions 14. The concave-convex fitting structure 7 on the magnet 2 is disposed on its two ends in the axial direction. The concave-convex fitting structure 7 includes an annular body 71 disposed inside the support portion 14 and a plurality of protrusions 72 protruding from the annular body 71 in the axial direction. The plurality of protrusions 72 are spaced apart in the circumferential direction, thereby creating grooves between the plurality of protrusions 72. The concave-convex fitting structure 7 on the magnet 2 includes a contoured portion that fits into the annular body 71 and the protrusions 72. Both ends of the magnet 2 abut against the radial outer edge of the support portion 14 and extend radially out of the support portion 14. Optionally, the magnet 2 can be integrally formed on the rotor body 1.

[0041] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A shaft-hole mating structure for a brushless motor rotor, characterized in that, include: The rotor body (1), the magnet (2) attached to the outside of the rotor body (1), and the shaft (3) fitted on the axis of the rotor body (1); The rotor body (1) includes a skeleton part (11) supporting the magnet (2) and a bearing part (12) for inserting the shaft (3). The skeleton part (11) is hollow and connected to the outer wall of the bearing part (12). The bearing part (12) defines a shaft tensioning structure (4) and a rotor transmission structure (5) on both sides of the connection part (13) of the skeleton part (11). The shaft tensioning structure (4) extends into the hollow inner side of the skeleton part (11). The shaft tensioning structure (4) includes a plurality of petal-shaped bodies spaced around the axis. The petal-shaped bodies elastically hug the shaft (3) and restrict the radial movement of the rotor body (1) relative to the shaft (3).

2. The shaft hole fitting structure of a brushless motor rotor according to claim 1, characterized in that: The connecting part (13) connects the skeleton part (11) and the bearing part (12) in the radial direction and forms the axial end of the rotor body (1). The petal includes a root (42) formed on the connecting part (13) and an elastic arm (41) extending from the root (42) away from the rotor drive structure (5).

3. The shaft hole fitting structure of a brushless motor rotor according to claim 2, characterized in that: The elastic arm (41) includes a clamping surface (45) that fits on the outer wall of the shaft (3). The clamping surface (45) includes at least a clamping section (43) that protrudes radially toward the axis and a retracting section (44) that extends on the axial side of the clamping section (43). The plurality of the petals control the dynamic clearance of the rotor body (1) relative to the shaft (3) through the clamping section (43). The retracting section (44) is at least connected to the connecting part (13) and provides a clamping surface that fits with the shaft (3).

4. The shaft hole fitting structure of a brushless motor rotor according to claim 3, characterized in that: The flap includes an initial pose detached from the shaft (3) and an assembly pose that mates with the shaft (3); In the initial position, the clamping section (43) protrudes close to the axis relative to the retracting section (44). In the assembly position, the clamping section (43) is abutted and expanded by the shaft (3), and the retracting section (44) is at least partially clamped to the shaft (3).

5. The shaft hole fitting structure of a brushless motor rotor according to claim 4, characterized in that: In its initial position, the retractable section (44) is inclined radially inward from the root (42) along the axial direction and is connected to the clamping section (43).

6. The shaft hole mating structure of a brushless motor rotor according to claim 3, characterized in that: The retractable section (44) is connected between the clamping section (43) and the connecting part (13). The clamping surface expands from the clamping section (43) toward the retractable section (44), and the clamping surface forms the minimum clamping surface on the clamping section (43).

7. The shaft hole mating structure of a brushless motor rotor according to claim 1, characterized in that: The rotor drive structure (5) is configured to extend axially away from the frame part (11) from the connecting part (13) so that the center of gravity of the rotor body (1) is offset along the axis toward the connecting part (13).

8. The shaft hole fitting structure of a brushless motor rotor according to claim 2, characterized in that: The elastic arm (41) has a guide opening (6) on its open side, and the guide opening (6) forms the maximum clamping surface.

9. The shaft hole fitting structure of a brushless motor rotor according to claim 1, characterized in that: The frame part (11) has support parts (14) on both sides of the shaft end. The magnet (2) is sleeved on the frame part (11) and abuts against the support parts (14). The magnet (2) and the support parts (14) have a concave-convex fit structure (7).

10. The shaft hole fitting structure of a brushless motor rotor according to claim 2, characterized in that: A material stacking section (421) is provided between the root (42) of the elastic arm (41) and the connecting part (13).

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