Motor and rotor assembly

Abstract

The utility model provides a motor and a rotor assembly. The rotor assembly comprises a magnet and a rotor core, the magnet is of a segmented structure and comprises a plurality of magnet segments which are evenly spaced in the circumferential direction, the rotor core comprises a center part and a plurality of peripheral segments which are evenly spaced in the circumferential direction, and the magnet segments and the peripheral segments are arranged adjacent to each other. The motor comprises a stator assembly and the rotor assembly. The stator assembly includes a stator having stator slots and stator teeth defined by the stator slots, and a winding wound around the stator teeth. According to the utility model, by using the SmFeN material, the use amount of copper can be reduced by about 40%, the effective material of the motor can be reduced by about 35%, and the manufacturing cost is obviously reduced.

Description

Technical Field

[0001] This utility model relates to electric motors. Specifically, on one hand, this utility model relates to a rotor assembly of an electric motor. On the other hand, this utility model relates to an electric motor including the rotor assembly, such as an SmFeN motor. Background Technology

[0002] Currently used rare-earth permanent magnet materials, such as neodymium iron boron (NdFeB) magnets, while possessing excellent magnetic properties, also have drawbacks. In particular, the widespread use of neodymium has led to a continuous increase in its price, thereby increasing manufacturing costs. Compared to NdFeB magnets, SmFeN (Samarium Iron Nitrogen) magnets, due to their lower manufacturing costs, are expected to become the next generation of rare-earth permanent magnet materials, with widespread applications in high-temperature environments such as motors.

[0003] SmFeN magnets are typically manufactured using injection molding or compression molding. There is a need to optimize motors that use SmFeN magnets. Utility Model Content

[0004] The purpose of this invention is to improve the SmFeN motor.

[0005] In a first aspect, the present invention provides a rotor assembly for an electric motor, comprising a magnet and a rotor core. The magnet has a segmented structure, comprising a plurality of magnet segments evenly spaced apart along the circumference. The rotor core comprises a central portion and a plurality of outer peripheral segments evenly spaced apart along the circumference. Each magnet segment and each outer peripheral segment are arranged adjacent to each other.

[0006] According to an embodiment, the magnet segment is an SmFeN magnet, for example, made by bonding, and the rotor core is a laminated structure.

[0007] According to the embodiment, the ratio of the pole pitch (i.e., the outer diameter of the rotor assembly * π / number of poles) to the length of the magnet segment in the radial direction is 1-1.5.

[0008] According to the embodiment, the magnetization direction of the SmFeN magnet is tangential, and the magnetization directions of each magnet segment are opposite to each other.

[0009] According to an embodiment, the ratio of the length of the magnet segment in the radial direction to the thickness of the magnet segment in the magnetization direction (i.e., tangential direction) is 1.6-2.2.

[0010] According to the embodiment, the remanence Br of the SmFeN magnet is greater than 0.66T.

[0011] According to the embodiment, the coercivity of the SmFeN magnet at the knee point of the JH demagnetization curve at 140 degrees Celsius (in this example, the knee point is located 5% below Br, i.e., 0.95Br) is greater than 160 kA / m.

[0012] According to an embodiment, the rotor assembly also includes a rotor housing, which is, for example, an injection-molded component. This arrangement allows the magnet segments and rotor core to be installed within the rotor housing during injection molding.

[0013] Preferably, to facilitate the positioning of the rotor core, the rotor core is provided with positioning through holes, for example, two holes, distributed radially, and the rotor housing is provided with positioning posts, for example, two posts, at corresponding positions, which pass through the positioning through holes. This arrangement allows the rotor assembly to be stably positioned in the rotor housing.

[0014] In a second aspect, the present invention provides an electric motor comprising a stator assembly and the aforementioned rotor assembly. The stator assembly includes a stator and windings, the stator having stator slots and stator teeth defined by the stator slots, and the windings being wound on the stator teeth.

[0015] According to an embodiment, the rotor assembly has an internal rotor configuration.

[0016] According to the embodiments, the motor is a 12-slot 8-pole, 12-slot 14-pole, 12-slot 10-pole, 18-slot 16-pole, or 18-slot 12-pole motor.

[0017] According to an embodiment, the ratio of the stator's outer diameter to its inner diameter is greater than 1.25.

[0018] According to an embodiment, the ratio of the stator tooth width to the stator yoke thickness is less than 1.6.

[0019] According to an embodiment, the air gap between the stator assembly and the rotor assembly, that is, half the difference between the inner diameter of the stator and the outer diameter of the rotor assembly, is equal to 0.05-0.1 times the thickness of the magnet segment in the magnetization direction (i.e., tangential direction).

[0020] According to an embodiment, the ratio of the stator tooth width to the thickness of the magnet segment in the magnetization direction (i.e., tangential direction) is greater than 0.95.

[0021] According to the embodiment, the ratio of the ampere-turns of the magnet segment (i.e., the quotient of the number of turns of the winding coil multiplied by the maximum demagnetizing current and then divided by the number of magnetic poles) to the coercivity of the SmFeN magnet at the knee point of the JH demagnetizing curve at 140 degrees Celsius (in this example, the knee point is located 5% below Br, i.e., 0.95Br) is less than 0.9.

[0022] According to this utility model, by adopting the above arrangement, the amount of copper used in the SmFeN material is reduced by about 40%, the effective material of the motor is reduced by about 35%, and the manufacturing cost is greatly reduced. Attached Figure Description

[0023] The embodiments of the present invention will be explained in more detail in the accompanying drawings, in which:

[0024] Figure 1This is a schematic diagram of the stator assembly and rotor assembly of the motor according to an embodiment of the present utility model;

[0025] Figure 2 yes Figure 1 A schematic diagram of the stator assembly of the motor in the diagram;

[0026] Figure 3 yes Figure 1 A schematic diagram of the rotor assembly of the motor;

[0027] Figure 4 yes Figure 1 A schematic perspective view of the rotor assembly of the motor in the diagram;

[0028] Figure 4A yes Figure 4 A schematic perspective view of the rotor housing of the rotor assembly in the diagram;

[0029] Figure 4B yes Figure 4 A schematic perspective view of the rotor assembly without the rotor housing.

[0030] In the accompanying drawings, embodiments of the present invention are shown in a simplified manner for clarity. The drawings are not necessarily shown to scale. Detailed Implementation

[0031] The following reference Figures 1-4B The embodiments of this utility model are described in detail below.

[0032] Figure 1 The SmFeN motor 1 shown is an embodiment of the present invention, including a stator assembly 10 comprising a stator 11 and a winding 12. The stator 11 has stator slots 11b and stator teeth 11a defined by the stator slots, and the winding 12 is wound around the stator teeth 11a. It also includes a rotor assembly 20 with a magnet 21 and a rotor core 22. The magnet 21 has a segmented structure, comprising a plurality of magnet segments evenly spaced circumferentially. The rotor core 22 includes a central portion 22a and a plurality of outer peripheral segments 22b evenly spaced circumferentially, with each magnet segment and each outer peripheral segment arranged adjacent to each other. In this example, the magnet segments are SmFeN magnets, and the rotor core has a laminated structure.

[0033] As shown in the figure, the rotor assembly 20 has an internal rotor structure, and the motor is a 12-slot 14-pole motor, that is, it has 12 stator slots and 14 magnet segments. Alternatively, the motor can also be a 12-slot 8-pole, 12-slot 10-pole, 18-slot 16-pole, or 18-slot 12-pole motor.

[0034] Figure 2 and Figure 3 Detailed constructions of the stator assembly 10 and the rotor assembly 20 are shown respectively. In particular, the stator assembly and the rotor assembly are configured to satisfy at least one of the following:

[0035] PP / Lm is 1-1.5.

[0036] Lm / Wm is 1.6-2.2,

[0037] The remanence Br of the SmFeN magnet is greater than 0.66T.

[0038] The Hd5 of SmFeN magnets is >160kA / m

[0039] D1 / D2>1.25,

[0040] TWS / SY < 1.6,

[0041] TWS / Wm>0.95,

[0042] Air gap = (D2 - D3) / 2 = (0.05 - 0.1) * Wm

[0043] AT / Hd5 < 0.9

[0044] Where PP is the pole pitch, i.e., the outer diameter of the rotor assembly * π / number of poles; Lm is the radial length of the magnet segment; D1 is the outer diameter of the stator; D2 is the inner diameter of the stator; D3 is the outer diameter of the rotor assembly; TWS is the tooth width of the stator teeth; SY is the thickness of the stator yoke 11c; Wm is the thickness of the magnet segment in the magnetization direction; Hd5 is the coercivity of the SmFeN magnet at the knee of the JH demagnetization curve at 140 degrees Celsius, i.e., 5% below Br, i.e., 0.95Br; AT is the ampere-turns of the magnet segment, i.e., the quotient of the number of turns of the winding coil multiplied by the maximum demagnetization current and then divided by the number of poles.

[0045] Figure 3 In the SmFeN magnet, the magnetization direction is tangential, and the magnetization directions of each magnet segment are opposite to each other.

[0046] Figure 4 The rotor assembly 20 also includes a rotor housing 30, which is cylindrical, and the magnet 21 and the rotor core 22 are housed in the rotor housing 30.

[0047] Figure 4A and Figure 4B The structures of the rotor housing 30 and the rotor assembly 20 are shown respectively. As shown in the figure, the rotor housing 30 has a receiving groove 31 on its outer periphery to receive the magnet segment. The rotor core 22 is provided with two radially distributed positioning through holes 22c. The rotor housing 30 is provided with two radially distributed positioning posts 32 at corresponding positions, which pass through the positioning through holes 22c to facilitate the positioning of the rotor core 22.

[0048] Figure 4 and Figure 4AThe rotor housing 30 also includes a central through-hole 33, with bearing seats 34 at both ends for mounting the rotor shaft. Four mounting bosses 35 are provided on the upper end face, located radially outward from the central through-hole 33 and equidistant from each other. To reinforce the bearing seats 34, the rotor housing 30 also has four reinforcing ribs 34a at the junction of the bearing seats 34 and their end faces.

[0049] The above embodiments illustrate the principles of this invention in specific applications, and the wording and expressions used are illustrative rather than restrictive. It will be understood by those skilled in the art that the use of these wordings and expressions is not intended to exclude any equivalent examples of the illustrated and described features from the scope of this invention. Without exercising inventive capacity, those skilled in the art can make various modifications to the above embodiments in terms of form, use, and implementation details without departing from the principles and concept of this invention as defined in the claims.

[0050] In some cases, the features disclosed in this invention can be used independently of other features. On the other hand, when necessary, the features disclosed in this invention can be combined to provide various combinations.

Claims

1. A rotor assembly for an electric machine comprising a magnet and a rotor core, characterized in that, The magnet is of segmented construction comprising a plurality of magnet segments spaced evenly in the circumferential direction, and the rotor core comprises a central portion and a plurality of outer peripheral segments spaced evenly in the circumferential direction, each magnet segment and each outer peripheral segment being arranged adjacent to each other.

2. The rotor assembly of claim 1, wherein The magnet segments are SmFeN magnets, and the rotor core is of laminated construction.

3. The rotor assembly of claim 2, wherein, The magnetization direction of the magnet is tangential, and the magnetization direction of each magnet segment is opposite to each other.

4. The rotor assembly of claim 3, wherein The rotor assembly is configured to satisfy at least one of: PP / Lm is 1-1.5, Lm / Wm is 1.6-2.2, The remanence Br of the SmFeN magnet is >0.66T, The Hd5 of the SmFeN magnet is >160kA / m where PP is the pole pitch, i.e. the outer diameter of the rotor assembly * π / the number of poles, Lm is the length of the magnet segment in the radial direction, Wm is the thickness of the magnet segment in the magnetization direction, and Hd5 is the coercivity of the SmFeN magnet at the knee point of the JH demagnetization curve at 140 degrees Celsius, i.e. at the point 5% below Br, i.e. at 0.95Br.

5. The rotor assembly of any one of claims 1-4, wherein, The rotor assembly further comprises a rotor housing.

6. The rotor assembly of claim 5, wherein The rotor core is provided with a positioning through hole, and the rotor housing is provided with a positioning column at the corresponding position, which passes through the positioning through hole.

7. An electric machine comprising a stator assembly, the stator assembly comprising a stator and a winding, the stator having stator slots and stator teeth defined by the stator slots, the winding being wound on the stator teeth, characterized in that, The motor further comprises the rotor assembly according to any one of claims 1-6.

8. The electric machine of claim 7, wherein, The rotor assembly is of inner rotor construction.

9. The electric machine of claim 7 or 8, characterized in that The motor is a 12-slot 8-pole, 12-slot 14-pole, 12-slot 10-pole, 18-slot 16-pole or 18-slot 12-pole motor.

10. The electric machine of claim 9, wherein, The stator assembly and the rotor assembly are configured to satisfy at least one of: D1 / D2>1.25, TWS / SY<1.6, TWS / Wm>0.95, The air gap = (D2-D3) / 2 = (0.05-0.1)*Wm, AT / Hd5<0.9, where D1 is the outer diameter of the stator, D2 is the inner diameter of the stator, D3 is the outer diameter of the rotor assembly, TWS is the tooth width of the stator tooth, SY is the thickness of the stator yoke, Wm is the thickness of the magnet segment in the magnetization direction, Hd5 is the coercivity of the SmFeN magnet at the knee point of the JH demagnetization curve at 140 degrees Celsius, i.e. at the point 5% below Br, i.e. at 0.95Br, and AT is the ampere turns of the magnet segment, i.e. the number of turns of the winding coil multiplied by the maximum demagnetization current and then divided by the number of poles.

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