High-speed motor rotor and motor

Abstract

The invention belongs to the field of permanent magnet synchronous motors, and discloses a high-speed motor rotor and a motor. The motor rotor comprises a hollow motor rotating shaft, a composite rotor iron core sleeving the motor rotating shaft, a permanent magnet sleeving the composite rotor iron core, and a rotor sheath sleeving the permanent magnet. The composite rotor iron core comprises a magnetic conductive layer and a supporting layer; the magnetic conductive layer is of an annular structure and covers the radial outer side area of the composite rotor iron core, and the periphery of the magnetic conductive layer is attached to the lower surface of the permanent magnet in an arc mode. The supporting layer is located on the inner wall of the annular structure of the magnetic conductive layer and comprises a plurality of spokes. The spokes are arranged in the circumferential direction of the motor rotor and located under the contact positions between adjacent magnetic poles of the permanent magnets, and the lower surfaces of the spokes are in interference fit with the hollow motor rotating shaft. The invention aims to provide a rotor structure design for improving the limit rotation speed of the motor under the condition that the pretightening force of the rotor sheath is limited, so that the technical problem of limit rotation speed limitation of the existing motor is solved.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet synchronous motors, and more specifically, relates to a high-speed motor rotor and motor. Background Technology

[0002] In the field of high-speed motors, the structure of surface-mounted permanent magnets paired with rotor sleeves has become the mainstream choice for drive systems of high-end equipment such as aerospace, high-speed machine tools, and precision vacuum pumps due to its ease of assembly and magnetic circuit stability. In this structure, the rotor sleeve, as a core protective component, needs to apply a preload force to counteract the centrifugal force exerted on the rotor (especially the permanent magnets) during high-speed motor operation. As the motor speed increases, if the sleeve preload force is insufficient, gaps or even separation can easily occur between the permanent magnets and the rotor core. This not only causes magnetic circuit disorder and a surge in air gap magnetic flux density harmonics, leading to increased motor torque fluctuations and noise, but may also cause structural damage due to magnet collisions, directly triggering motor failure.

[0003] Because using alloy materials for the rotor sheath introduces significant eddy current losses, current high-speed motors often use carbon fiber resin composite materials. However, carbon fiber sheaths cannot be directly fitted with interference fits; they can only be fixed by high-tension winding and curing. The level of preload application is limited, which greatly restricts the motor's maximum speed. Therefore, there is an urgent need to design a high-speed motor rotor. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a high-speed motor rotor and motor, which aims to improve the motor's limiting speed under the condition of limited rotor sheath preload, thereby solving the technical problem of limiting the limiting speed of existing motors.

[0005] To achieve the above objectives, in one aspect of the present invention, a high-speed motor rotor is provided, comprising a hollow motor shaft, a composite rotor core sleeved on the motor shaft, a permanent magnet sleeved on the composite rotor core, and a rotor sheath sleeved on the permanent magnet. The composite rotor core includes a magnetic conductive layer and a support layer. The magnetic conductive layer has a ring structure and covers the radially outer region of the composite rotor core. The outer periphery of the magnetic conductive layer is arc-shaped and fits against the lower surface of the permanent magnet. The support layer is located on the inner wall of the ring structure of the magnetic conductive layer and includes multiple spokes. The spokes are arranged circumferentially along the motor rotor and are located directly below the contact point between adjacent magnetic poles of the permanent magnet. The lower surface is interference-fitted with the hollow motor shaft.

[0006] Preferably, when the permanent magnet is a tile-shaped permanent magnet, the spokes are located directly below the contact point between adjacent magnetic poles in the permanent magnet.

[0007] Preferably, the radial cross-section of the spoke is an arc surface that matches the surface of the hollow motor shaft, and the spoke is inserted into the motor shaft to form a keyway structure.

[0008] Preferably, at least two through holes are provided axially through the middle of the spoke, and the axial cross-section of the through holes is elliptical.

[0009] Preferably, the number of spokes is the same as the number of permanent magnet stages.

[0010] Preferably, the support layer is further provided with multiple sets of convex teeth, wherein the convex teeth in the convex teeth are evenly arranged between two adjacent spokes.

[0011] Preferably, the protruding tooth is an arc tooth with an axial cross-section of circular arc or an inverted triangular tooth with an axial cross-section of inverted triangle, and the wider end of the inverted triangular tooth is closer to the side of the motor shaft; The convex tooth group includes multiple arc teeth, multiple inverted triangular teeth, or a combination of arc teeth and inverted triangular teeth; when the convex tooth group includes a combination of arc teeth and inverted triangular teeth, the inverted triangular teeth are located on both sides of the spoke, and the arc teeth are located between the inverted triangular teeth.

[0012] Preferably, the connection between the spokes and the composite rotor core is rounded.

[0013] Preferably, the composite rotor core is 20%-40% of the mass of a solid rotor core with the same inner and outer diameter.

[0014] In another aspect of the present invention, a high-speed motor is provided, comprising at least one high-speed motor rotor as described above.

[0015] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: 1. This invention discloses a high-speed motor rotor, the rotor core of which is a composite rotor core (i.e., a spoked core), the structure of which includes a magnetic conductive layer and a support layer; the magnetic conductive layer has a ring structure, covering the radially outer region of the composite rotor core, and the outer periphery of the magnetic conductive layer is arc-shapedly fitted with the lower surface of the permanent magnet; the support layer is located on the inner wall of the ring structure of the magnetic conductive layer, and the support layer includes multiple spokes; the spokes are arranged circumferentially along the motor rotor, located directly below the contact point between adjacent magnetic poles of the permanent magnet, and the lower surface is interference-fitted with the hollow motor shaft. The spoked core structure supports the magnetic conductive layer and other structures above it through the interference fit between the spokes and the motor shaft; on the other hand, the spokes and the motor shaft transmit torque; at high speeds, the easy elastic deformation of the spokes enables the core and permanent magnet to self-adaptively fit; and while ensuring structural strength, it achieves lightweighting, thereby realizing a rotor structure design that improves the motor's limiting speed under the condition of limited rotor sleeve preload.

[0016] 2. Preferably, the present invention has at least two through holes axially extending through the middle of the spokes, which reduces the weight of the rotor and enhances the tensile deformation capacity of the spokes, making the radial displacement response of the spokes more sensitive.

[0017] 3. Preferably, the present invention has teeth on the support layer of the composite rotor core to ensure that the surface shape of the composite rotor core and the permanent magnet matches at high speed, thereby realizing differential adjustment of the compressive stress of the permanent magnet. Attached Figure Description

[0018] Figure 1 A schematic diagram of a planar structure of a high-speed motor rotor provided by the present invention; Figure 2 A detailed structural schematic diagram of the composite rotor core provided by the present invention.

[0019] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-Rotor sheath, 2-Permanent magnet, 3-Composite rotor core, 301-Magnetic conductive layer, 302-Inverted triangular teeth, 303-Circular arc teeth, 304-Spokes, 4-Motor shaft. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] In the description of this invention, it should be understood that the terms "center", "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 this 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 this invention. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection", and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an abutting connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In a first aspect of the present invention, a high-speed motor rotor is provided, the structure of which is as follows: Figure 1 and Figure 2 As shown, the whole is symmetrically distributed to ensure dynamic balance performance during high-speed operation. It includes a motor shaft 4, a composite rotor core 3 sleeved on the motor shaft 4, a permanent magnet 2 sleeved on the composite rotor core 3, and a rotor sleeve 1 sleeved on the permanent magnet 2. The permanent magnet 2 is a ring structure composed of multiple magnetic poles. Unlike conventional permanent magnet synchronous motors, the composite rotor core 3 of this invention has a composite structure, which is prone to tensile deformation at high speeds. The composite rotor core 3 is more tightly bonded to the permanent magnet. Its structure includes a magnetic conductive layer 301 and a support layer. The magnetic conductive layer 301 has a ring structure, covering the radially outer region of the composite rotor core 3. At the same time, the outer peripheral wall of the magnetic conductive layer 301 is arc-shapedly bonded to the lower surface of the permanent magnet 2 to ensure that the magnetic lines of force generated by the permanent magnet are transmitted in an orderly manner along the magnetic conductive layer 301. The support layer is located on the inner wall of the ring structure of the magnetic conductive layer 301 and includes multiple spokes 304. The spokes 304 are arranged circumferentially along the motor rotor and are located directly below the adjacent magnetic poles in the permanent magnet 2. The lower surface is interference-fitted with the motor shaft 4.

[0022] Furthermore, when the permanent magnet 2 is a tile-shaped permanent magnet, the spokes 304 are located directly below the contact point between adjacent parts of the permanent magnet 2. Raised teeth are provided on the lower surface of the support layer to ensure better contact between the permanent magnet 2 and the composite rotor core 3. In particular, when a typical tile-shaped permanent magnet rotates at high speed, the outer radius of rotation is large, resulting in greater force and expansion; the inner radius of rotation is small, resulting in less force and contraction. The composite rotor core 3 is supported by spokes. The tensile strain of the core near the spokes is relatively small, while the tensile strain of the core in the middle of the inner side of the two spokes (the middle of the permanent magnet) is relatively large. At high speeds, the permanent magnet is wider at the top and narrower at the bottom, with the two sides of the lower surface converging towards the center. By providing raised teeth 302 and 303 with different axial cross-sectional shapes in the composite rotor core 3, centrifugal force adaptive adjustment is achieved, ensuring a tight fit between the composite rotor core 3 and the permanent magnet 2.

[0023] Furthermore, the radial section of the spoke 304 is an arc surface that matches the surface of the motor shaft 4. The spoke 304 is inserted into the motor shaft to form a keyway structure, and its lower surface is interference-fitted with the hollow motor shaft 4.

[0024] Furthermore, at least two through holes are axially penetrating the center of the spoke 304. To prevent stress concentration, the number of elliptical holes should not be one; at least two through holes should be provided. Considering safety margins, and to facilitate tensioning, the through holes are designed with an elliptical axial cross-section. The through holes in the center of the spokes reduce rotor weight and enhance the tensile deformation capacity of the spokes, making the radial displacement response of the spokes more sensitive.

[0025] Furthermore, the spokes 304 are distributed circumferentially along the motor rotor and are located directly below the contact point between adjacent magnetic poles of the permanent magnet 2. The number of spokes 304 corresponds to the number of magnetic poles in the permanent magnet 2 (they are the same), and is twice the number of pole pairs. Ignoring axial and circumferential segmentation, the number of spokes 304 is 2p, the number of magnetic poles in the permanent magnet 2 is 2p, and the number of pole pairs in the motor is p.

[0026] In this invention, the spokes primarily serve three functions: 1. The spokes, with their interference fit to the motor shaft, support the magnetic layer and other structures above it; 2. The spokes, through a keyway-like structure, transmit torque to the motor shaft; 3. Compared to a solid rotor core, the composite rotor core is more prone to tensile deformation under centrifugal force. At high speeds, the composite rotor core exhibits a more pronounced outward radial displacement, resulting in a tighter fit between the rotor core and the permanent magnet. Consequently, under a constant pressure exerted by the sheath on the permanent magnet, the composite rotor core generates a greater compressive force below the permanent magnet, effectively increasing the protective performance of the sheath. Although the rotor sheath generates greater circumferential stress, the circumferential stress is generally much smaller than its circumferential strength, thus not limiting the motor's maximum speed.

[0027] Furthermore, the support layer is also provided with multiple sets of convex teeth, with the convex teeth in the convex teeth set being evenly arranged between two adjacent spokes 304. And the number of convex teeth sets corresponds to the number of units in the permanent magnet 2 (they are the same).

[0028] Furthermore, to accommodate strain magnitudes at different locations, two types of protruding teeth are provided on the lower surface of the support layer according to different axial cross-sectional shapes. The first type: axially arc-shaped teeth with a relatively flat shape, evenly distributed between the two spokes. At high speeds, the lower surface of the permanent magnet converges towards the center from both sides. To highlight the strain in the middle of the composite rotor core, the arc-shaped teeth in the middle of the composite rotor core are used to increase the centrifugal force in the center, thereby making the composite rotor core and permanent magnet fit more tightly. The arc shape and flat design are to disperse the centrifugal force and avoid excessive tensile strain in the very center of the composite rotor core. The second type: axially triangular teeth with a narrower upper section and a wider lower section, with the wider end closer to the motor shaft, evenly distributed between the two spokes. The core strain near the spokes is smaller. At high speeds, the area above the spokes is where the composite rotor core first separates from the permanent magnet. To maintain the fit between the composite rotor core and the permanent magnet, inverted triangular teeth are provided on both sides of the spokes to generate a larger centrifugal force in a smaller area, highlighting local strain. The preferred third method is to use a combination of arc teeth and inverted triangular teeth, with the inverted triangular teeth located on both sides of the spokes and the arc teeth located between the inverted triangular teeth, thereby leveraging the advantages of the first and second methods mentioned above.

[0029] Furthermore, the connections between the spokes and the composite rotor core 3 are all rounded. The spokes experience higher stress, resulting in larger fillet radii, while the fillet radii at the teeth are smaller.

[0030] Furthermore, the connections between the spokes and the composite rotor core 3 are all rounded. The spokes experience higher stress, resulting in larger fillet radii, while the fillet radii at the teeth are smaller.

[0031] Furthermore, the composite rotor core has a mass of 20%-40% that of a solid rotor core with the same inner and outer diameter.

[0032] Furthermore, the motor shaft 4 can be a hollow motor shaft or a solid motor shaft.

[0033] Furthermore, the magnetic conductive layer 301 and the support layer are formed by an integral stamping process without any splicing gaps. In a second aspect of the invention, a high-speed motor is provided, comprising at least one high-speed motor rotor as described in any of the preceding claims. Because the composite rotor core of the present invention has a larger radial strain, a greater contact pressure between the composite rotor core and the permanent magnet, and a better fit, the maximum permissible speed of the motor rotor is greater, resulting in an extremely high maximum safe speed for the corresponding motor, thus providing a foundation for improving the performance of the motor towards higher speeds and higher power density.

[0034] The present invention will now be described in further detail with reference to the accompanying drawings.

[0035] Example 1: This invention discloses a 6-pole motor rotor with a pole arc coefficient of 1, such as... Figure 1 As shown, the whole is symmetrically distributed, including the motor shaft 4 (specifically, a hollow motor shaft with an outer diameter of R26.5mm and an inner diameter of R20mm), the composite rotor core 3 (outer diameter of R44mm and spoke inner diameter of 25mm) sleeved outside the hollow motor shaft, the permanent magnet 2 (specifically, a 6-pole, 11mm thick) sleeved outside the composite rotor core 3, and the rotor sheath 1 (outer diameter of R56mm and thickness of 1mm) sleeved outside the permanent magnet. The composite rotor core has a composite structure including a magnetic conductive layer 301 (5mm thick on one side) and a support layer. The magnetic conductive layer 301 has a ring structure, covering the radially outer area of ​​the composite rotor core 3, and the outer peripheral wall of the magnetic conductive layer 301 is arc-shaped and fits against the lower surface of the permanent magnet 2. The support layer is located on the inner wall of the ring structure of the magnetic conductive layer 301, including 6 spokes 304 (spanning angle 10°) and 6 sets of convex teeth (each set of convex teeth specifically includes two inverted triangular teeth on the spoke side and one arc tooth between the two inverted triangular teeth). The spokes 304 are arranged circumferentially along the motor rotor and are located directly below the adjacent units in the permanent magnet 2, and the lower surface is interference-fitted with the motor shaft 4. Specifically, the parameters involved in this motor rotor are shown in Table 1 below.

[0036] Table 1: Material and dimensional parameters of each component in Example 1

[0037] The present invention also discloses a motor rotor containing a solid rotor core, which differs from the above-mentioned 6-pole motor rotor with a pole arc coefficient of 1 in that it has a composite rotor core and a solid rotor core.

[0038] Table 2 compares the radial displacements of solid rotor cores and composite rotor cores, considering only the elastic strain caused by centrifugal force without applying an interference fit. The elastic strains of the two topologies differ by nearly an order of magnitude.

[0039] Table 2: Comparison of radial displacement of solid rotor core and composite rotor core

[0040] Table 3 compares the rotational speeds at which the magnets separate from the rotor core under the same rotor sleeve interference (same preload). The rotational speed at which the composite rotor core separates from the permanent magnet is slightly higher than that of the solid core.

[0041] Table 3: Comparison of rotational speeds when the magnet separates from the rotor core

[0042] In summary, as shown in Tables 2 and 3, at high speeds, the composite rotor core exhibits greater radial strain, greater contact pressure between the rotor core and the permanent magnet, better fit, and a larger maximum allowable operating speed.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations. The above-described embodiments are merely preferred embodiments given to fully illustrate this invention, and their scope of protection is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this invention are all within the scope of protection of this invention.

Claims

1. A high-speed motor rotor, characterized in that, It includes a hollow motor shaft, a composite rotor core sleeved on the motor shaft, a permanent magnet sleeved on the composite rotor core, and a rotor sheath sleeved on the permanent magnet; The composite rotor core includes a magnetic conductive layer and a support layer. The magnetic conductive layer has a ring structure and covers the radially outer region of the composite rotor core. The outer periphery of the magnetic conductive layer is arc-shaped and fits against the lower surface of the permanent magnet. The support layer is located on the inner wall of the ring structure of the magnetic conductive layer and includes multiple spokes. The spokes are arranged circumferentially along the motor rotor and are located directly below the contact point between adjacent magnetic poles of the permanent magnet. The lower surface is interference-fitted with the hollow motor shaft.

2. The high-speed motor rotor according to claim 1, characterized in that, When the permanent magnet is a tile-shaped permanent magnet, the spokes are located directly below the contact point between adjacent magnetic poles in the permanent magnet.

3. The high-speed motor rotor according to claim 1, characterized in that, The spoke radial cross section is an arc surface that matches the surface of the hollow motor shaft, and the spoke is inserted into the motor shaft to form a keyway structure.

4. The high-speed motor rotor according to claim 1, characterized in that, At least two through holes are provided axially through the middle of the spoke, and the axial cross-section of the through holes is elliptical.

5. The high-speed motor rotor according to claim 1, characterized in that, The number of spokes is the same as the number of poles of the permanent magnet.

6. The high-speed motor rotor according to claim 1, characterized in that, The support layer is also provided with multiple sets of convex teeth, and the convex teeth in the convex teeth are evenly arranged between two adjacent spokes.

7. The high-speed motor rotor according to claim 6, characterized in that, The protruding tooth is either an arc tooth with an axial cross-section of a circular arc or an inverted triangular tooth with an axial cross-section of an inverted triangle, with the wider end of the inverted triangular tooth closer to the side of the motor shaft. The convex tooth group includes multiple arc teeth, multiple inverted triangular teeth, or a combination of arc teeth and inverted triangular teeth; when the convex tooth group includes a combination of arc teeth and inverted triangular teeth, the inverted triangular teeth are located on both sides of the spoke, and the arc teeth are located between the inverted triangular teeth.

8. The high-speed motor rotor according to claim 1, characterized in that, The connections between the spokes and the composite rotor core are all rounded.

9. The high-speed motor rotor according to claim 1, characterized in that, The composite rotor core is 20%-40% of the mass of a solid rotor core with the same inner and outer diameter.

10. A high-speed motor, characterized in that, It includes at least one high-speed motor rotor as described in any one of claims 1-9.

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