Rotor assembly, electric machine and device comprising the same

Abstract

The present application relates to a rotor assembly, and an electric machine and an apparatus including the same. The rotor assembly includes a rotor including a rotor core and a magnet embedded in the rotor core between axial end surfaces of the rotor, and a balance weight having a bottom surface facing the axial end surface of the rotor. The balance weight includes a support portion protruding in an axial direction and a radial direction from an outer peripheral edge of the bottom surface, the support portion is configured to form an air gap portion between the balance weight and the magnet, and the support portion is located radially outward of the magnet.

Description

Technical Field

[0001] This application relates to a rotor assembly and a motor and device including the rotor assembly, such as a motor and compressor for a compressor. Background Technology

[0002] The technical content provided in this section is intended to help those skilled in the art understand the present invention, and does not necessarily constitute prior art.

[0003] Electric motors are typically used to drive crankshafts, which in turn drive moving parts such as compressors to compress working fluids. When equipment or machines that include crankshafts (e.g., compressors) are in operation, problems such as vibration and noise often occur due to the imbalance of the movement of the moving parts.

[0004] To address this motion imbalance, counterweights that provide a counter-centrifugal force are typically placed on the moving parts to balance the imbalance, thereby reducing vibration and noise. An electric motor consists of a stator and a rotor that rotates relative to the stator. Commonly, counterweights are fixed to the rotor so that they rotate with the rotor, thus achieving dynamic balancing. Therefore, the rotor and counterweights fixed to each other can be referred to as a rotor assembly.

[0005] Rotors typically contain magnets. To prevent magnetic leakage, the balance weights can be made of non-magnetic materials, or a partition made of non-magnetic material can be placed between the balance weights and the rotor. It is well known that rotor assemblies primarily use high-density non-magnetic materials such as brass and austenitic stainless steel, which are relatively expensive. Therefore, rotor assemblies with balance weights or partitions made of non-magnetic materials are more expensive.

[0006] In one existing rotor assembly, the radially outer surface of the bottom of the counterweight is spaced apart from the magnet by a certain distance (i.e., forming an air gap) to prevent magnetic leakage. However, this rotor assembly is prone to premature failure due to factors such as rivet breakage.

[0007] Therefore, it is desirable to provide a rotor assembly that is low in cost, can effectively prevent magnetic leakage, and can improve the support stress. Summary of the Invention

[0008] This section provides a general summary of the invention, rather than a full disclosure of the invention's complete scope or all its features.

[0009] One object of the present invention is to provide a rotor assembly that can improve the support force while effectively preventing magnetic leakage.

[0010] Another object of the present invention is to provide a rotor assembly with lower material and assembly costs.

[0011] To achieve at least one of the above objectives, a rotor assembly is provided, which may include: a rotor including a rotor core and a magnet embedded in the rotor core between axial end faces of the rotor; and a counterweight with its bottom surface facing the axial end face of the rotor. The counterweight includes a support portion projecting from the outer peripheral edge of the bottom surface in both axial and radial directions, the support portion being configured to form an air gap between the counterweight and the magnet, and the support portion being located radially outward of the magnet.

[0012] According to the rotor assembly of this disclosure, due to the protruding shape and supporting function of the support portion, a gap or air gap is formed between the magnet and other parts of the bottom surface, thereby effectively preventing magnetic leakage. Furthermore, since the support portion is located on the radially outer side of the bottom surface, the distance between the resultant force support point of the support portion and the rotation center O is relatively large, thus significantly improving the stress conditions of the balance block and fasteners.

[0013] In some examples according to this disclosure, the balance block includes a plurality of said supports arranged discretely along the circumferential direction.

[0014] In some examples according to this disclosure, the axial extension height of the support is greater than or equal to 3 mm.

[0015] In some examples according to this disclosure, the shortest distance between adjacent supports and the magnet is greater than or equal to 3 mm.

[0016] In some examples according to this disclosure, the balance block further includes a stop that extends axially from the bottom surface and is configured to prevent the magnet from protruding from the axial end face.

[0017] In some examples according to this disclosure, the balance block is attached to the rotor by fasteners, and the stop is positioned adjacent to the fasteners.

[0018] In some examples according to this disclosure, the stop is a single member extending from the support for each magnet.

[0019] In some examples according to this disclosure, the stop extends from an adjacent support.

[0020] In some examples according to this disclosure, the balance block is made of a magnetically conductive material.

[0021] In some examples according to this disclosure, the magnets are arranged in a serrated shape along the circumferential direction.

[0022] According to another aspect of this disclosure, an electric motor including the aforementioned rotor assembly and stator is provided.

[0023] According to another aspect of this disclosure, an apparatus including the aforementioned motor is provided. Attached Figure Description

[0024] The features and advantages of one or more embodiments of the present invention will become more readily understood from the following description with reference to the accompanying drawings, in which:

[0025] Figure 1 A perspective view of a rotor assembly according to an embodiment of the present disclosure is provided;

[0026] Figure 2 for Figure 1 An exploded perspective view of the rotor assembly;

[0027] Figure 3 for Figure 1 A cross-sectional schematic diagram of the rotor assembly;

[0028] Figure 4 To show Figure 1 A three-dimensional schematic diagram of the bottom surface of the upper balancing block;

[0029] Figure 5 for Figure 1 A top view of the rotor;

[0030] Figures 6A to 6D A plan view illustrating various bottom surfaces of the balance block according to this disclosure; and

[0031] Figure 7 This is a schematic diagram of the force analysis of the rotor assembly. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments. This detailed description is for illustrative purposes only and is not intended to limit the invention or its applications or uses.

[0033] Figures 1 to 5 Various schematic diagrams of rotor assemblies according to embodiments of the present disclosure are shown. Reference will be made below. Figures 1 to 5 The rotor assembly 1 according to an embodiment of the present disclosure will be described.

[0034] like Figures 1 to 5As shown, rotor assembly 1 includes a rotor 20 and an upper balancing block 10 and a lower balancing block 30 located at opposite ends of the rotor 20. The upper balancing block 10 and the lower balancing block 30 are connected to the rotor 20 by fasteners 50 (e.g., rivets or bolts). The upper balancing block 10 has a through hole 11 for inserting the fastener 50. The rotor 20 has a through hole 21 for inserting the fastener 50. The lower balancing block 30 has a through hole 31 for inserting the fastener 50. The through holes 11, 21, and 31 are aligned to insert the fastener 50, thereby forming rotor assembly 1.

[0035] The upper balance block 10 has a base 12 and a counterweight 14 extending upward (in the axial direction) from the base 12. The base 12 is configured for attaching the upper balance block 10. The counterweight 14 is configured to achieve dynamic balance. Similarly, the lower balance block 30 has a base 32 and a counterweight 34 extending downward (in the axial direction) from the base 32. The base 32 is configured for attaching the lower balance block 30. The counterweight 34 is configured to achieve dynamic balance.

[0036] See Figure 5 The rotor 20 includes a cylindrical rotor core 22 and a magnet 23 inserted or embedded in the rotor core 22.

[0037] The inventors of this application have discovered that existing rotor assemblies often fail prematurely due to the breakage of fasteners (rivets) 50. To address this problem, the inventors conducted a stress analysis of existing rotor assemblies and, based on this analysis, proposed this invention. The following will refer to… Figure 7 The stress conditions of the rotor assembly are explained.

[0038] like Figure 7 As shown, the upward force SF represents the supporting force of the rotor on the upper balance block 10'; the downward force FF represents the fastening force that secures the upper balance block 10' to the rotor 20' via n rivets 50'; and the radially outward force IF represents the inertial force generated when the rotor assembly rotates. The horizontal distance between the resultant point of the supporting force SF and the rotation center O is a; the vertical distance between the inertial force IF and the end face (support surface) of the rotor 20' is h.

[0039] Under force balance, the upward supporting force SF exerted by the rotor on the upper balance block should be equal to the downward tightening force FF of the n screws on the upper balance block, that is, n*FF=SF.

[0040] Under torque balance, the counterclockwise torque generated by the supporting force SF should be equal to the clockwise torque generated by the inertial force IF, that is, SF*a=IF*h.

[0041] If the resultant force of the supporting force SF is closer to the center of rotation O, that is, radially inward towards the center of rotation O, then the distance a is smaller, and correspondingly, the supporting force SF and the fastening force FF are larger. In this case, the screw is prone to premature breakage.

[0042] In existing rotor assemblies, an air gap is formed between the radially outer part of the bottom surface of the balance block and the rotor magnet to prevent magnetic leakage. Therefore, the resultant force of the balance block's supporting force is applied closer to the rotation center O, making the screws prone to breakage.

[0043] Based on the above findings, the inventors of this application have proposed this invention. The rotor assembly according to this disclosure includes a balance block with an improved bottom structure to improve stress conditions, such as... Figure 2 The upper surface structure (bottom surface structure) of the lower balancing block 30 shown and Figure 4 The lower surface structure (bottom surface structure) of the upper balancing block 12 shown.

[0044] exist Figures 1 to 3 In the example, the structure of counterweight 14 is different from that of counterweight 34, while the structure of base 12 is basically the same as that of base 32. It should be understood that the structures of upper balance block 10 and lower balance block 30 can be exactly the same, partially the same, or completely different, depending on the dynamic balancing requirements.

[0045] Figure 6A It is shown Figure 2 The lower balance block and Figure 4 A plan view of the bottom structure of the upper balancing block. The following will refer to... Figure 6A To describe the bottom structure of the balance block according to this disclosure. For example... Figure 6A As shown, the base 12 or 32 of the balance block includes a bottom surface 100, a support portion 110 extending from the outer peripheral edge 101 of the bottom surface 100 in the axial and radial directions, and a hole 150 for inserting a fastener 50.

[0046] The support portion 110 is used to support the balance weight on the rotor. The balance weight may include multiple support portions 110. Figure 6A The example shown has six support portions 110. The multiple support portions 110 can be arranged discretely along the circumferential direction and / or distributed at equal intervals along the circumferential direction.

[0047] The support portion 110 is located radially outward of the magnet 23. It should be understood that "radial outward" here refers to the relative positional relationship between the integral support portion and the integral magnet, such as... Figure 6AAs shown. Therefore, it is not excluded that a part of the support is radially inside a part of the magnet. The resultant support point of each support 110 is located radially outside the radial center line RC of the bottom surface 100. The support 110 is provided in an area that avoids the magnet 23 (as shown by the dashed line), that is, it is provided in an area of ​​the rotor that does not have the magnet 23 (as shown by the dashed line).

[0048] Due to the protruding shape and supporting function of the support portion 110, a gap or air gap is formed between the magnet 23 and other parts of the bottom surface 100, thereby effectively preventing magnetic leakage. The shortest distance between adjacent support portions 110 and the magnet 23 can be greater than or equal to 3 mm to ensure its ability to prevent magnetic leakage. For example, as... Figure 6A As shown, there is a constant distance d between the sidewall of the adjacent support portion 110 and the side edge of the magnet 23, and the value of d can be greater than or equal to 3 mm. In an example not shown, the side edge of the magnet 23 and the sidewall of the support portion 110 are not arranged parallel to each other, but the shortest distance between the side edge of the magnet 23 and the sidewall of the support portion 110 can still be greater than or equal to 3 mm.

[0049] In addition, the axial extension height of the support portion 110 can be greater than or equal to 3 mm to ensure that the height of the formed void or air gap can be greater than or equal to 3 mm, thereby ensuring its ability to prevent magnetic leakage.

[0050] Since the support portion 110 is located on the radially outer side of the bottom surface 100, the distance between the point of application of the resultant force of the support portion 110 and the rotation center O is relatively large. As a result, the supporting force of the rotor on the balance block and the fastening force of the fasteners on the balance block can be reduced, that is, the stress condition of the balance block and the fasteners is significantly improved.

[0051] Therefore, the support portion 110 can not only effectively prevent magnetic leakage, but also significantly improve the stress conditions of each component of the rotor assembly and thus extend the service life of the rotor assembly.

[0052] Furthermore, since the support portion 110 provides an air gap between the balance block and the magnet, meaning the balance block does not contact the magnet, the entire balance block can be made of a magnetically conductive material (e.g., an iron-based metallurgical material), or the partition made of a non-magnetically conductive material (e.g., brass, austenitic stainless steel plate) placed between the balance block and the magnet can be omitted. This significantly reduces the cost of the balance block and the rotor assembly.

[0053] It should be understood that the structure of the support portion 110 is not limited to the specific example shown in the figure, but can be varied as long as it can prevent magnetic leakage and improve the stress conditions. For example, the support portion 110 can be formed as a single piece along the outer peripheral edge 101 of the bottom surface 100. The shape of the support portion 110 can vary depending on the arrangement of the magnets.

[0054] The base 12 or 32 of the counterweight may also include a stop 130A that extends axially from the bottom surface 100. The stop 130A is configured to prevent the magnet 23 (as shown by the dashed line) from protruding from the axial end face of the rotor 20.

[0055] exist Figure 6A In the example, the stop portion 130A is in the form of a short column. Each stop portion 130A is used to prevent a corresponding magnet from protruding from the axial end face of the rotor 20. Preferably, the stop portion 130A has a minimum contact area with the magnet 23 while still achieving the stopping function. In this case, even if the stop portion 130A is made of a magnetically conductive material, its magnetic leakage capability is limited.

[0056] The stop portion 130A can be positioned close to the hole 150 for receiving fasteners. In this way, the stop portion 130A can provide additional support for the balance block near the connection part (hole 150), thereby further improving the stress situation of the balance block.

[0057] It should be understood that the structure or shape of the stop 130A can vary. For example, as Figure 6B As shown, the stop portion 130B has an elongated oval shape. (As indicated...) Figure 6C As shown, the stop portion 13C is a curved elongated shape or rib shape extending between adjacent support portions 110 to provide a stopping effect on two adjacent magnets simultaneously. It should be understood that the stop portion 13C can be a linearly extending elongated shape or rib shape.

[0058] The stop part can be as follows Figure 6A and Figure 6B The diagram shows a single component for each magnet, or it could be as follows: Figure 6C The diagram shows a component positioned for two adjacent magnets.

[0059] In addition, such as Figure 6D As shown, the stop portion can be omitted. For example, if the magnet can be securely fixed to the rotor core 22 by adhesive or other means, the stop portion can be omitted.

[0060] The balance block with the above-described bottom structure can be used for various arrangements of magnets. See also Figure 5The rotor 20 has 12 magnets. Two magnets 23, which can be V-shaped, are arranged between adjacent through holes 21 for inserting fasteners 50. Thus, all magnets 23 are arranged in a generally serrated shape along the circumferential direction. Each support 110 is located radially outward of the adjacent V-shaped magnet 23. In this way, the support 110 can have a larger size on the radially outward side and a smaller size on the radially inward side, so that the point of force support of the support 110 is closer to the outer peripheral edge 101 of the bottom surface 100. This configuration not only facilitates the arrangement of the magnets 23, but also improves the stress conditions of the support and the fastener. It should be understood that the arrangement of the magnets is not limited to the specific example shown, but can be varied.

[0061] The rotor assembly described above according to this disclosure is applicable to various motors, such as permanent magnet motors. The motor also includes a stator (not shown), about which the rotor assembly is rotatable. Furthermore, motors including the described rotor assembly are applicable to various devices or machines, such as compressors.

[0062] In this application, the directional terms "upper" and "lower," etc., are used merely for descriptive purposes and should not be considered restrictive. Furthermore, in this application, magnetic and non-magnetic materials can be understood according to their common meaning in the art; for example, magnetic materials can guide materials with relatively high magnetic permeability, while non-magnetic materials can guide materials with relatively low magnetic permeability.

[0063] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the specific embodiments described and shown herein, and various changes can be made to the exemplary embodiments by those skilled in the art without departing from the scope defined by the claims.

Claims

1. A rotor assembly, comprising: A rotor, the rotor comprising a rotor core and magnets embedded in the rotor core between axial end faces of the rotor; as well as A balance block, the bottom surface of which faces the axial end face of the rotor. The balance block includes a support portion that extends and protrudes from the outer peripheral edge of the bottom surface in both axial and radial directions. The support portion is configured to form an air gap between the balance block and the magnet so that the balance block does not contact the magnet, and the support portion is located radially outside the magnet.

2. The rotor assembly according to claim 1, wherein, The balance block includes a plurality of support portions discretely arranged along the circumferential direction.

3. The rotor assembly according to claim 1 or 2, wherein the axial extension height of the support portion is greater than or equal to 3 mm.

4. The rotor assembly according to claim 1 or 2, wherein, The shortest distance between adjacent support portions and the magnet is greater than or equal to 3 mm.

5. The rotor assembly according to claim 1 or 2, wherein, The balance block also includes a stop portion extending axially from the bottom surface, the stop portion being configured to prevent the magnet from protruding from the axial end face.

6. The rotor assembly according to claim 5, wherein, The balance block is attached to the rotor by fasteners, and the stop is positioned adjacent to the fasteners.

7. The rotor assembly according to claim 5, wherein, The stop is a single component extending from the support for each magnet.

8. The rotor assembly according to claim 5, wherein, The stop extends from the adjacent support portion.

9. The rotor assembly according to claim 1 or 2, wherein, The balance block is made of magnetically conductive material.

10. The rotor assembly according to claim 1 or 2, wherein, The magnets are arranged in a sawtooth shape along the circumferential direction.

11. An electric motor comprising a rotor assembly and a stator according to any one of claims 1 to 10.

12. An apparatus comprising the motor according to claim 11.

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