Rotor assembly and motor with same

Abstract

The invention provides a rotor assembly and a motor with the same, the rotor assembly comprises a rotor iron core and a first permanent magnet, a first accommodating groove penetrating through the axial direction of the rotor iron core is formed in the rotor iron core, the first accommodating groove extends along the radial direction of the rotor iron core, and the first permanent magnet is inserted into the first accommodating groove. The first permanent magnet comprises a main body part and a reduction part formed on one side of the main body part, the size of the reduction part is smaller than that of the main body part, the main body part is close to the outer circle of the rotor core relative to the reduction part, and the reduction part is located at the center of the rotor core relative to the main body part. According to the invention, the main body part with a larger volume is closer to the outer circle of the rotor core, the reduced part with a smaller volume is closer to the center of the rotor core, and the area close to the center of the rotor core is the easily-magnetic-leakage part of the rotor, namely, the main body part of the first permanent magnet avoids the easily-magnetic-leakage part of the rotor, so that magnetic leakage can be reduced; the magnetic performance of the rotor is ensured.

Description

Rotor assembly and motor having it Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a rotor assembly and a motor having the same. Background Technology

[0002] With market demand, the trend towards DC-DC motors in household appliances is growing. Currently, most brushless motors used in the industry are radial magnetic field surface-mount structures, resulting in low power density and low material utilization. Due to rising raw material prices, high-power-density motors are becoming the development trend for brushless DC motors. In permanent magnet motors, higher rotor magnetic properties are typically required to improve motor performance. Within a limited structural framework, compared to surface-mount and embedded radial rotors, an internal tangential rotor structure can effectively increase the magnetic flux area and improve the effective air gap flux, thereby enhancing motor performance. However, the internal tangential structure is prone to magnetic leakage, leading to low magnet utilization and wasted manufacturing costs. Summary of the Invention

[0003] Therefore, the present invention provides a rotor assembly that can solve the technical problem that the built-in tangential rotor structure is prone to magnetic leakage, resulting in low magnet utilization.

[0004] To address the aforementioned problems, the present invention provides a rotor assembly including a rotor core and a first permanent magnet. The rotor core has a first receiving groove extending through its axial direction, and the first receiving groove also extends radially along the rotor core. The first permanent magnet is inserted into the first receiving groove. The first permanent magnet includes a main body portion and a reduced portion formed on one side of the main body portion. The volume of the reduced portion is smaller than the volume of the main body portion. The main body portion is closer to the outer circle of the rotor core relative to the reduced portion, and the reduced portion is closer to the center of the rotor core relative to the main body portion.

[0005] In some embodiments, the first receiving slot has a first slot wall near the center of the rotor core, and the side of the reduced portion away from the main body abuts against the first slot wall.

[0006] In some embodiments, along the radial direction of the rotor core, the sum of the lengths of the main body portion and the reduced portion is L1, and the length of the reduced portion is L2, where 1mm ≤ L2 ≤ 1 / 3L1.

[0007] In some embodiments, along the axial direction of the rotor core, the height of the main body portion is H1, and the height of the reduced portion is H2, where 2mm ≤ H2 ≤ 1 / 2H1.

[0008] In some embodiments, a protrusion is formed on the rotor core, and the main body portion has a side facing the center of the rotor core, with the protrusion stopping on the side.

[0009] In some embodiments, the rotor core is provided with a second receiving groove extending through its axial direction, the second receiving groove also extending radially along the rotor core, a second permanent magnet is inserted in the second receiving groove, the sum of the lengths of the main body portion and the reduced portion along the radial direction of the rotor core is equal to the length of the second permanent magnet, and the height of the second permanent magnet along the axial direction of the rotor core is equal to the height of the main body portion.

[0010] In some embodiments, the number of first receiving slots constructed on the rotor core is at least two, the number of second receiving slots constructed on the rotor core is at least two, and each of the first receiving slots and each of the second receiving slots is alternately distributed along the circumference of the rotor core. Each of the first receiving slots is fitted with a first permanent magnet, and each of the second receiving slots is fitted with a second permanent magnet.

[0011] In some embodiments, the rotor core, each of the first permanent magnets and each of the second permanent magnets are injection molded together to form a plastic encapsulation.

[0012] In some embodiments, the rotor core includes a first core segment and two second core segments, the two second core segments clamping the first core segment from both sides. The first core segment includes a plurality of first teeth spaced apart circumferentially, and the second core segment includes a ring body and a plurality of second teeth spaced apart circumferentially along the ring body. Each second tooth is connected to the ring body through a magnetic isolation bridge.

[0013] The present invention also provides an electric motor, including the aforementioned rotor assembly.

[0014] The present invention provides a rotor assembly and a motor having the same, which have the following advantages: the larger main body is closer to the outer circle of the rotor core, and the smaller reduced part is closer to the center of the rotor core. The area close to the center of the rotor core is the part of the rotor that is prone to magnetic leakage. That is, the main body of the first permanent magnet avoids the part of the rotor that is prone to magnetic leakage, thereby reducing magnetic leakage and ensuring the magnetic performance of the rotor. The reduced part is also smaller in size, which can reduce the waste of magnetic material. Attached Figure Description

[0015] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0016] Figure 1 is a schematic diagram of the permanent magnets of the rotor assembly in an embodiment of the present invention inserted into the rotor core; Figure 2 is a cross-sectional view of the permanent magnets of the rotor assembly in an embodiment of the present invention inserted into the rotor core; Figure 3 is a schematic diagram of the rotor assembly in an embodiment of the present invention; Figure 4 is a schematic diagram of the rotor core of the rotor assembly in an embodiment of the present invention; Figure 5 is a schematic diagram of the permanent magnets of the rotor assembly in an embodiment of the present invention; Figure 6 is a schematic diagram of the plastic encapsulation shell of the rotor assembly in an embodiment of the present invention; Figure 7 is a schematic diagram of the first lamination of the first core segment of the rotor core of the rotor assembly in an embodiment of the present invention; Figure 8 is a schematic diagram of the second lamination of the second core segment of the rotor core of the rotor assembly in an embodiment of the present invention.

[0017] The reference numerals in the attached figures are as follows: 1. Rotor core; 2. First permanent magnet; 21. Main body; 22. Reduced portion; 3. First receiving groove; 4. Protrusion; 5. Second receiving groove; 6. Second permanent magnet; 7. Plastic encapsulation shell; 8. First tooth body; 9. Ring body; 10. Second tooth body. Detailed Implementation

[0018] 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0019] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0020] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0021] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0022] Referring to Figures 1 to 8, according to an embodiment of the present invention, a rotor assembly is provided, including a rotor core 1 and a first permanent magnet 2. The rotor core 1 has a first receiving groove 3 extending through its axial direction. The first receiving groove 3 also extends radially along the rotor core 1. The first permanent magnet 2 is inserted into the first receiving groove 3. The first permanent magnet 2 includes a main body portion 21 and a reduced portion 22 formed on one side of the main body portion 21. The volume of the reduced portion 22 is smaller than the volume of the main body portion 21. The main body portion 21 is closer to the outer circle of the rotor core 1 relative to the reduced portion 22, and the reduced portion 22 is closer to the center of the rotor core 1 relative to the main body portion 21.

[0023] In this technical solution, the larger main body 21 is closer to the outer circle of the rotor core 1, and the smaller reduced part 22 is closer to the center of the rotor core 1. The area close to the center of the rotor core 1 is the part of the rotor that is prone to magnetic leakage. That is, the main body 21 of the first permanent magnet 2 avoids the part of the rotor that is prone to magnetic leakage, thereby reducing magnetic leakage and ensuring the magnetic performance of the rotor. The reduced part 22, because of its smaller size, can also reduce the waste of magnetic materials.

[0024] Referring to Figure 1, the first receiving groove 3 has a first groove wall near the center of the rotor core 1, and the reduced portion 22 abuts against the first groove wall on the side away from the main body portion 21.

[0025] In this embodiment, in addition to reducing the amount of magnetic material used to reduce magnetic leakage, the reduced portion 22 also provides support and limits for the installation of the first permanent magnet 2 in the first receiving groove 3, ensuring that the installation position of the first permanent magnet 2 in the first receiving groove 3 is accurate.

[0026] Referring to Figure 2, along the radial direction of the rotor core 1, the sum of the lengths of the main body 21 and the reduced portion 22 is L1, and the length of the reduced portion 22 is L2. If the length of the reduced portion 22 is too short, it will not effectively reduce leakage flux; if the length of the reduced portion 22 is too long, the amount of the first permanent magnet 2 will be reduced too drastically, significantly impacting the overall magnetic flux. After repeated verification, it was found that when 1mm ≤ L2 ≤ 1 / 3L1, both leakage flux reduction and magnetic flux reduction can be achieved.

[0027] Referring to Figure 2, along the axial direction of the rotor core 1, the height of the main body 21 is H1, and the height of the reduced portion 22 is H2. If the height of the reduced portion 22 is too large, it will not effectively reduce leakage flux; if the height of the reduced portion 22 is too small, the amount of the first permanent magnet 2 will be reduced too drastically, significantly impacting the overall magnetic flux. After repeated verification, it was found that when 2mm ≤ H2 ≤ 1 / 2H1, both leakage flux reduction and magnetic flux reduction can be achieved.

[0028] Referring to Figures 1, 4 and 5, a protrusion 4 is formed on the rotor core 1, and the main body 21 has a side facing the center of the rotor core 1, with the protrusion 4 stopping on the side.

[0029] In this technical solution, the protrusion 4 and the main body 21 cooperate to form a foolproof structure, which guides and limits the installation of the first permanent magnet 2, further eliminating the possibility of assembly errors of the first permanent magnet 2 and ensuring product quality. Preferably, there are two protrusions 4 formed on the rotor core 1, which are distributed on both sides of the first receiving groove 3, and both protrusions 4 stop on the side, so that the first permanent magnet 2 is subjected to balanced force.

[0030] Referring to Figures 1, 4, and 5, a second receiving groove 5 is constructed on the rotor core 1, extending through its axial direction. The second receiving groove 5 also extends radially along the rotor core 1. A second permanent magnet 6 is inserted into the second receiving groove 5. Along the radial direction of the rotor core 1, the sum of the lengths of the main body portion 21 and the reduced portion 22 is equal to the length of the second permanent magnet 6. Along the axial direction of the rotor core 1, the height of the second permanent magnet 6 is equal to the height of the main body portion 21.

[0031] In this embodiment, the first permanent magnet 2 is obtained by cutting the second permanent magnet 6. Although the cut first permanent magnet 2 can reduce magnetic leakage, it also loses magnetic flux. The second permanent magnet 6 is equivalent to the original complete permanent magnet. By inserting the second permanent magnet 6 into the rotor core 1, the magnetic flux can be increased, thereby ensuring both the reduction of magnetic leakage and the guarantee of magnetic flux.

[0032] Referring to Figures 1, 4 and 5, the rotor core 1 has at least two first receiving slots 3 and at least two second receiving slots 5. The first receiving slots 3 and the second receiving slots 5 are alternately distributed along the circumference of the rotor core 1. Each first receiving slot 3 is fitted with a first permanent magnet 2, and each second receiving slot 5 is fitted with a second permanent magnet 6.

[0033] In this technical solution, the alternating distribution of the first receiving slots 3 and the second receiving slots 5 along the circumference of the rotor core 1 ensures that the first permanent magnets 2 and the second permanent magnets 6 are also alternating along the circumference of the rotor core 1. This guarantees a balanced distribution of the rotor magnetic circuit and prevents abnormal vibration and noise from the motor caused by uneven magnetic circuit distribution. Specifically, the first permanent magnets 2 and the second permanent magnets 6 are arranged alternately with N and S poles along the circumference at 360° / 2P, where 2P is the number of magnetic poles of the rotor, and the number of first permanent magnets 2 and second permanent magnets 6 is P.

[0034] Referring to Figures 3 to 6, the rotor core 1, each of the first permanent magnets 2, and each of the second permanent magnets 6 are injection molded together, further improving structural strength and precision. After injection molding, all permanent magnets are completely fixed inside the rotor core 1, eliminating the need for additional components to fix all permanent magnets. Simultaneously, a plastic seal 7 is inevitably formed on the rotor core 1 after injection molding. It should be noted that, to improve the accuracy of the rotor's magnetic circuit distribution, the rotor is magnetized as a whole, further reducing problems such as magnetic pole misalignment and unevenness during component assembly. The magnetization direction is tangential, therefore the final rotor assembly can be called an internal tangential rotor structure. It is understandable that the protrusion 4's limiting effect on the main body 21 also prevents the first permanent magnet 2 from shifting towards the center of the rotor core 1 during injection molding, avoiding magnetic pole misalignment, further improving rotor precision, and ensuring dynamic balance.

[0035] Referring to Figures 4, 7 and 8, the rotor core 1 includes a first core segment and two second core segments. The two second core segments clamp the first core segment from both sides. The first core segment includes a plurality of first teeth 8 distributed circumferentially. The second core segment includes a ring 9 and a plurality of second teeth 10 distributed circumferentially along the ring 9. Each second tooth 10 is connected to the ring 9 through a magnetic bridge.

[0036] In this embodiment, receiving slots are formed between adjacent first tooth bodies 8 and adjacent second tooth bodies 10 on the rotor core 1, and these receiving slots include all the first receiving slots 3 and the second receiving slots 5. The fact that the first core segment only includes multiple first tooth bodies 8 indicates that no magnetic isolation bridge is set between the receiving slots on the first core segment, while magnetic isolation bridges are set between the receiving slots on the second core segment. The rotor structure in which the two second core segments clamp the first core segment from both sides can fix the first tooth bodies 8 without magnetic isolation bridges, and can also reduce the number of magnetic isolation bridges, thereby further improving rotor performance and reducing leakage flux. Specifically, the first core segment can be formed by stacking multiple first core laminations, and the second core segment can be formed by stacking multiple second core laminations, all of which are silicon steel sheets. More specifically, the rotor core 1 can also include two first core segments and three second core segments, with the second core segments, first core segments, second core segments, first core segments, and second core segments stacked sequentially to form the rotor core 1.

[0037] The manufacturing steps of the rotor assembly are as follows: Step 1: The silicon steel sheets are stacked axially to form the rotor core 1 using a stamping die; Step 2: Each first permanent magnet 2 and each second permanent magnet 6 are sequentially embedded into the respective receiving slots of the rotor core 1; Step 3: The assembled rotor assembly is placed in a plastic-coated mold and high-temperature injection molding is performed to form a plastic-encapsulated rotor.

[0038] The present invention also provides an electric motor, including the aforementioned rotor assembly.

[0039] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above are merely preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A rotor assembly, characterized in that, The device includes a rotor core (1) and a first permanent magnet (2). The rotor core (1) has a first receiving groove (3) extending through its axial direction. The first receiving groove (3) also extends radially along the rotor core (1). The first permanent magnet (2) is inserted into the first receiving groove (3). The first permanent magnet (2) includes a main body portion (21) and a reduced portion (22) formed on one side of the main body portion (21). The volume of the reduced portion (22) is smaller than the volume of the main body portion (21). The main body portion (21) is closer to the outer circle of the rotor core (1) relative to the reduced portion (22). The reduced portion (22) is closer to the center of the rotor core (1) relative to the main body portion (21).

2. The rotor assembly according to claim 1, characterized in that, The first receiving groove (3) has a first groove wall near the center of the rotor core (1), and the reduced portion (22) abuts against the first groove wall on the side away from the main body portion (21).

3. The rotor assembly according to claim 1 or 2, characterized in that, Along the radial direction of the rotor core (1), the sum of the lengths of the main body (21) and the reduced portion (22) is L1, and the length of the reduced portion (22) is L2, 1mm≤L2≤1 / 3L1.

4. The rotor assembly according to claim 1 or 2, characterized in that, Along the axial direction of the rotor core (1), the height of the main body (21) is H1, and the height of the reduced part (22) is H2, 2mm≤H2≤1 / 2H1.

5. The rotor assembly according to claim 1, characterized in that, The rotor core (1) has a protrusion (4) formed thereon, and the main body (21) has a side facing the center of the rotor core (1), and the protrusion (4) stops on the side.

6. The rotor assembly according to claim 1, characterized in that, The rotor core (1) is provided with a second receiving groove (5) extending through its axial direction. The second receiving groove (5) also extends radially along the rotor core (1). A second permanent magnet (6) is inserted in the second receiving groove (5). Along the radial direction of the rotor core (1), the sum of the lengths of the main body (21) and the reduced portion (22) is equal to the length of the second permanent magnet (6). Along the axial direction of the rotor core (1), the height of the second permanent magnet (6) is equal to the height of the main body (21).

7. The rotor assembly according to claim 6, characterized in that, The rotor core (1) has at least two first receiving slots (3) and at least two second receiving slots (5). Each first receiving slot (3) and each second receiving slot (5) is alternately distributed along the circumference of the rotor core (1). Each first receiving slot (3) is fitted with a first permanent magnet (2), and each second receiving slot (5) is fitted with a second permanent magnet (6).

8. The rotor assembly according to claim 7, characterized in that, The rotor core (1), each of the first permanent magnets (2) and each of the second permanent magnets (6) are fixed together by injection molding and form a plastic shell (7).

9. The rotor assembly according to claim 1, characterized in that, The rotor core (1) includes a first core segment and two second core segments. The two second core segments clamp the first core segment from both sides. The first core segment includes a plurality of first teeth (8) spaced apart along the circumference. The second core segment includes a ring (9) and a plurality of second teeth (10) spaced apart along the circumference of the ring (9). Each second tooth (10) is connected to the ring (9) through a magnetic bridge.

10. An electric motor, characterized in that it includes the rotor assembly as described in any one of claims 1 to 9.

Images