Stator assembly of magnetism gathering type motor

Abstract

The stator assembly comprises a magnetic ring, a ground lug, a bearing, a gasket and a plastic casing, the gasket is arranged between the bearing and the plastic casing, the ground lug is connected with the magnetic ring, the magnetic ring is a multi-stage ferrite magnetic ring, the magnetic ring is of a magnet structure with an annular Halbach array so as to achieve the unilateral magnetism gathering effect, and the magnetic ring is connected with the plastic casing. The surface magnetic flux density distribution of the magnetic ring is in a sinusoidal waveform. According to the stator assembly of the magnetism gathering type motor, the magnetic ring has higher air gap magnetic field intensity, the torque output capacity of the motor can be improved, and meanwhile the vibration noise of the motor is reduced.

Description

Technical Field

[0001] The present invention relates to a motor, and more particularly to a stator assembly of a magnetic field concentrated motor. Background Art

[0002] As market competition becomes increasingly fierce, the requirements for noise of micromotors used in automobiles are getting higher and higher. In order to maintain competitive advantage, reducing noise is of great significance. Summary of the invention

[0003] In order to achieve the above-mentioned purpose of reducing noise, the present invention provides a stator assembly of a magnetic field concentrated motor.

[0004] According to the stator assembly of the magnetic field focusing motor of the present invention, it includes a magnetic ring, a grounding plate, a bearing, a gasket and a plastic housing, wherein the gasket is arranged between the bearing and the plastic housing, the grounding plate is connected to the magnetic ring, the magnetic ring is a multi-stage ferrite magnetic ring, and the magnetic ring is a magnet structure with an annular Halbach array to achieve a unilateral magnetic field focusing effect, and the surface magnetic flux density distribution of the magnetic ring is a sinusoidal waveform.

[0005] In a preferred embodiment, the plastic housing is plastic-coated to fix the magnetic ring, the grounding sheet, the bearing and the gasket.

[0006] In a preferred embodiment, the top of the plastic housing has four first cavities, and four first positioning inserts are inserted into the first cavities during the overmolding process to position the magnetic ring in the circumferential and height directions.

[0007] In a preferred embodiment, the bottom of the plastic housing has four second cavities, and four second positioning inserts are inserted into the second cavities during the overmolding process to position the magnetic ring in the circumferential and height directions.

[0008] In a preferred embodiment, a positioning plate is integrally formed on the plastic housing to fix the magnetic ring in height direction.

[0009] In a preferred embodiment, the magnetic ring has a groove, and the grounding sheet is fixed in the groove.

[0010] In a preferred embodiment, the plastic housing has four third cavities, and four third positioning inserts are inserted into the third cavities during the overmolding process to position the grounding plate in height and circumferential directions.

[0011] In a preferred embodiment, the outer diameter of the bearing is larger than the outer diameter of the spacer.

[0012] In a preferred embodiment, the plastic housing has three fourth cavities evenly distributed circumferentially and a fifth cavity located in the center, three fourth positioning inserts are inserted into the fourth cavities during the overmolding process to position the bearing in height and circumferential directions, and one fifth positioning insert is inserted into the fifth cavity during the overmolding process to position the gasket in height and circumferential directions.

[0013] In a preferred embodiment, the plastic housing is made of BMC or SMC.

[0014] According to the stator assembly of the magnetic field concentrated motor of the present invention, the magnetic ring has a higher air gap magnetic field strength, which can improve the torque output capacity of the motor and reduce the vibration noise of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic assembly diagram of a stator assembly of a magnetic flux concentrated motor according to a preferred embodiment of the present invention.

[0016] Figure 2 yes Figure 1 Cross-sectional view of the stator assembly.

[0017] Figure 3 The figure shows the assembly method of magnetic tiles according to the prior art.

[0018] Figure 4 yes Figure 1 Top view of the stator assembly.

[0019] Figure 5 yes Figure 1 Bottom view of the stator assembly.

[0020] Figure 6 yes Figure 1 Another cross-sectional view of the stator assembly.

[0021] Figure 7 yes Figure 1 Schematic diagram of the partial structure of the stator assembly.

[0022] Figure 8 Show Figure 1 The connection between the magnetic ring and the grounding plate.

[0023] Fig. 9 yes Figure 1 Partial bottom view of the stator assembly.

[0024] Fig.10 Show Figure 1 The positioning of bearings and gaskets in the specific injection molding process. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0026] The motor according to a preferred embodiment of the present invention is a brushless motor, including a housing, a stator structure and a rotor structure, wherein the stator structure is fixedly installed in the housing to form a stator assembly, and a rotating magnetic field is generated when current passes through the stator structure, and the rotor structure includes a rotor permanent magnet, and the rotating magnetic field generated by the current change in the stator structure interacts with the rotor permanent magnet to generate torque. In this embodiment, the housing is a plastic housing 5, and the stator structure is connected to form a stator assembly by injection molding using the plastic housing 5, that is, the plastic housing 5 and the stator structure are integrally formed, which shortens the assembly time of the motor, improves assembly efficiency, and reduces costs. It should be understood that the integral molding here is only an example and not a limitation, and the stator assembly arranged separately is also applicable here.

[0027] like Figure 1 and Figure 2 As shown, the stator structure includes a magnetic ring 1, a grounding plate 2, a bearing 3 and a gasket 4, and a plastic housing 5 over-molds and fixes the magnetic ring 1, the grounding plate 2, the bearing 3 and the gasket 4 to form a stator assembly. In the specific injection molding process, the magnetic ring 1, the grounding plate 2, the bearing 3 and the gasket 4 are positioned in the mold through their respective positioning inserts, and then the plastic is injected along the plastic inlet to fix all the components (i.e., the magnetic ring 1, the grounding plate 2, the bearing 3 and the gasket 4) while forming the plastic housing 5.

[0028] In the prior art, the casing is formed by deep drawing of magnetic conductive materials, which is relatively costly. In the present invention, the casing is changed to a plastic casing 5. In particular, the inventors have found that if conventional thermoplastic plastics such as PA66 and PBT are used to form the plastic casing 5, the magnetic ring 1 as an insert may crack after injection molding due to its high molding temperature. Therefore, the plastic casing 5 of the present invention uses low-temperature injection molding materials. The low temperature of the injection molding process will not cause the magnetic ring 1 to crack, and the precision requirements for parts are relatively low. Preferably, it is a bulk molding compound (Bulk Molding Compound, BMC) thermosetting material. The BMC material has a high hardness and meets the strength requirements of the motor. In other embodiments, it may also be a sheet molding compound (Sheet Molding Compound, SMC).

[0029] The magnetic ring 1 is a Halbach ferrite magnetic ring, which provides a magnetic field for the motor through the magnet structure of the annular Halbach array. The multi-stage magnetic ring applies an internal orientation magnetic field during the molding stage, so that the magnetic moment inside the magnetic ring is arranged into a Halbach array structure, showing a unilateral magnetic concentration effect. This structure makes the magnetic flux density of the working surface / application surface large, and the magnetic field intensity is 1.4 to 2 times the intensity of the traditional magnet of equal volume, while the magnetic flux density of the non-working surface is close to zero. The unilateral magnetic field distribution generated by the magnet self-shielding effect of the magnetic ring 1 does not require the plastic housing 5 to use metal materials to provide a path for it. The surface magnetic flux density distribution of the magnetic ring 1 in the present invention is a sinusoidal waveform, and has a larger motor air gap magnetic density at the same magnetic material dosage, which is beneficial to reduce the vibration noise of the motor. Compared with the prior art, the magnetic ring 1 of the present invention has a higher air gap magnetic field intensity, which can improve the output capacity of the motor torque and reduce the vibration noise of the motor. The magnetic ring material is ferrite, and the Halbach internal orientation magnetization is adopted. This Halbach ferrite magnetic ring has a higher air gap magnetic field strength than the ferrite magnetic tile radial magnetization in mass production. The pole pair number P of the magnetic ring can be P=1, 2, 3, 4... (P≥1). By changing the pole pair number, the operating characteristics of the motor can be adjusted to meet different application requirements. For example, increasing the pole pair number can reduce the speed of the motor while increasing the torque.

[0030] In the present invention, the magnetic ring 1 is integrally encapsulated by injection molding of the plastic housing 5, and the motor assembly line can omit the assembly process of the magnetic ring 1, reduce the investment of the stator assembly line, improve production efficiency, and reduce costs. In the prior art, in order to ensure the performance and stability of the motor, the magnetic tile 1' is usually accurately positioned and fixedly assembled on the inner side of the housing 5' by the magnetic tile glue 1a', such as Figure 3 Specifically, the magnetic tile glue 1a' is applied on the surface of the magnetic tile 1' facing the housing 5', and after heating, drying and fixing, the magnetic tile 1' is assembled in the housing 5'. The magnetic tile 1 of the present invention is integrally injection-molded and packaged by the plastic housing 5, and the magnetic tile glue 1a' is not needed, thereby reducing the parts required to be assembled on the motor assembly line.

[0031] In the specific injection molding process, the magnetic ring 1 is positioned and fixed in the circumferential direction and the height direction by the upper and lower positioning inserts. Figure 4 As shown, the top of the plastic housing 5 has four first cavities 51, and four first positioning inserts are inserted into the first cavities 51 from above to position the magnetic ring 1 in the height direction and the circumferential direction. Figure 5 As shown, the bottom of the plastic housing 5 has four second cavities 52, and four second positioning inserts are inserted from below into the second cavities 52 to position the magnetic ring 1 in the height direction and the circumferential direction. Figure 6 As shown, the plastic housing 5 directly forms a positioning plate 53 to fix the magnetic ring 1 in height direction.

[0032] The grounding plate 2 connects the stator structure to the ground to eliminate electric charge and ensure the reliability of the electrical connection. In the present invention, the grounding plate 2 is integrally packaged by injection molding of the plastic housing 5. The motor assembly line can reduce the assembly process of the grounding plate 2, reduce the required equipment investment, improve production efficiency, and reduce costs. In the specific injection molding process, such as Figure 7 As shown, the top of the plastic housing 5 has four third cavities 54, and four third positioning inserts are inserted into the third cavities 54 to position the grounding plate 2 in height and circumferential directions. Figure 8 As shown, the top of the magnetic ring 1 has a groove, and the bottom end of the grounding plate 2 is fixed in the groove. The present invention can optimize the EMC capability of the motor while completing the grounding function by adding a grounding plate 2 connected to the magnetic ring 1 at the contact position between the grounding wire and the stator structure.

[0033] The bearing 3 radially supports the rotor structure to allow the rotor structure to rotate freely inside the stator structure, and the gasket 4 is arranged between the bearing 3 and the plastic housing 5 to axially support the rotor structure to adjust the gap or reduce vibration and reduce noise. In the present embodiment, the bearing 3 is a metal part provided by powder metallurgy, such as iron-copper based powder metallurgy material (Fe-Cu BASED). In the present embodiment, the gasket 4 is a polyetheretherketone (PEEK) gasket, such as PEEK5600CF30. In the present invention, the bearing 3 and the gasket 4 are integrally injection-molded and packaged by the plastic housing 5, and the motor assembly line can reduce the press-fitting process of the bearing and the gasket, reduce the required equipment investment, improve production efficiency, and reduce costs.

[0034] In the specific injection molding process, such as Fig. 9 As shown, the bearing 3 and the gasket 4 are positioned in the height direction and the circumferential direction by the lower mold and the fourth and fifth positioning inserts 6, 7. In particular, the outer diameter of the bearing 3 is larger than the outer diameter of the gasket 4, thereby leaving a fixed position for the fourth positioning insert 6, so that the bearing 3 and the gasket 4 can be integrally injection molded. Figure 8 As shown, the bottom of the plastic housing 5 also has three fourth cavities 55 evenly distributed circumferentially and a fifth cavity 56 located in the center, three fourth positioning inserts 6 are inserted into the fourth cavity 55 to position the bearing 3 in height and circumferential directions, and a fifth positioning insert 7 is inserted into the fifth cavity 56 to position the gasket 4 in height and circumferential directions.

[0035] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A stator assembly of a magnetic field concentrated motor, characterized in that: The stator assembly includes a magnetic ring, a grounding plate, a bearing, a gasket and a plastic casing, wherein the gasket is arranged between the bearing and the plastic casing, the grounding plate is connected to the magnetic ring, the magnetic ring is a multi-stage ferrite magnetic ring, and the magnetic ring is a magnet structure with an annular Halbach array to achieve a unilateral magnetic focusing effect, and the surface magnetic flux density distribution of the magnetic ring is a sinusoidal waveform.

2. The stator assembly according to claim 1, characterized in that: The plastic housing is plastic-coated to fix the magnetic ring, grounding plate, bearing and gasket.

3. The stator assembly according to claim 2, characterized in that: The top of the plastic housing is provided with four first cavities, and four first positioning inserts are inserted into the first cavities during the overmolding process to position the magnetic ring in the circumferential and height directions.

4. The stator assembly according to claim 2, characterized in that: The bottom of the plastic housing is provided with four second cavities, and the four second positioning inserts are inserted into the second cavities during the overmolding process to position the magnetic ring in the circumferential and height directions.

5. The stator assembly according to claim 1, characterized in that: A positioning plate is integrally formed on the plastic housing to fix the magnetic ring in height.

6. The stator assembly according to claim 1, characterized in that: The magnetic ring has a groove, and the grounding sheet is fixed in the groove.

7. The stator assembly according to claim 2, characterized in that: The plastic housing has four third cavities, and four third positioning inserts are inserted into the third cavities during the overmolding process to position the grounding plate in height and circumferential directions.

8. The stator assembly according to claim 2, characterized in that: The outer diameter of the bearing is larger than the outer diameter of the spacer.

9. The stator assembly according to claim 8, characterized in that: The plastic housing has three fourth cavities evenly distributed circumferentially and a fifth cavity located in the center. Three fourth positioning inserts are inserted into the fourth cavity during the overmolding process to position the bearing in height and circumferential directions. A fifth positioning insert is inserted into the fifth cavity during the overmolding process to position the gasket in height and circumferential directions.

10. The stator assembly according to claim 1, characterized in that: The plastic casing is made of BMC or SMC.

Images