CN114765388A

CN114765388A - Axial flux electric machine and stator

Info

Publication number: CN114765388A
Application number: CN202011622688.9A
Authority: CN
Inventors: 柳绪丹; 刘新华; 何茂军; 李青
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-07-19

Abstract

The present application provides a stator for an axial flux electric machine, comprising: a printed circuit board comprising a substrate and a coil disposed on a surface of the substrate, wherein the coil is formed from a conductive trace on the surface of the substrate; and a core, wherein the core is embedded within the printed circuit board. The invention also provides an axial flux motor comprising the stator. The axial flux machine and stator of the present application have a more compact structure, higher reliability and simplified manufacturing process.

Description

Axial flux machine and stator

Technical Field

The invention relates to the field of axial flux motors, in particular to a stator comprising a PCB winding and an axial flux motor comprising the stator.

Background

In order to overcome the defects of complicated structure, low precision, large volume, inconvenient production and the like commonly existing in the conventional coil-type winding, the Printed Circuit Board (PCB) winding manufactured by the modern PCB (printed Circuit board) process is adopted in many fields. Especially in the field of electric drives, many axial flux machines with PCB windings are emerging. Since the thickness of the PCB winding is very small and a very small length/diameter ratio can be achieved, such a motor can be applied to various applications having high requirements for installation space, such as hard disk drives, drones, household appliances, and the like.

At present, axial flux motors with PCB windings mainly adopt a coreless stator structure, namely, the stator is only provided with the PCB windings and no iron core. Such a coreless structure, while advantageous for weight reduction and elimination of cogging, is difficult to achieve high torque density and limits the range of applications for the motor. To this end, an axial flux machine has been proposed comprising a stator with a core and PCB windings, wherein the core is laminated or attached as a separate additional layer on or to the PCB windings to constitute the stator. Although the axial flux motor can realize high torque density, the axial flux motor has the defect that the iron core of the stator obviously increases the axial length of the motor, and is not beneficial to the miniaturization of the motor. In addition, the assembly of the core of the stator with the PCB winding requires a separate process step during the manufacturing process, and the mounting accuracy and the degree of firmness are limited.

Accordingly, there is a need for an improved stator with PCB windings and an axial flux machine including the same to address the above-mentioned problems.

Disclosure of Invention

The present invention is directed to overcoming the disadvantages of the prior art and providing a stator having PCB windings and an axial flux motor including the same having a more compact structure, higher reliability and simplified manufacturing process.

To this end, according to an aspect of the present application, there is provided a stator for an axial flux electric machine, comprising: a printed circuit board comprising a substrate and a coil disposed on a surface of the substrate, wherein the coil is formed from a conductive trace on the surface of the substrate; and a core, wherein the core is embedded within the printed circuit board.

According to an exemplary embodiment, the core is disposed not to exceed a surface of the printed circuit board on which the coil is disposed.

According to an exemplary embodiment, the core at least partially overlaps the coil.

According to an exemplary embodiment, the substrate is a multilayer structure, and the core is embedded in at least one layer of the substrate.

According to an exemplary embodiment, the coils are disposed on both surfaces of the substrate.

According to an exemplary embodiment, the printed circuit board includes a plurality of coils, and the stator includes a plurality of cores, the plurality of coils and the plurality of cores being uniformly distributed in a corresponding manner in a circumferential direction of the printed circuit board.

According to an exemplary embodiment, the printed circuit board includes a plurality of substrates stacked.

According to an exemplary embodiment, the coil is provided on a surface of at least two of the plurality of substrates, and the core is embedded in the at least two of the plurality of substrates.

According to another aspect of the present application, there is provided an axial-flux electric machine, wherein the axial-flux electric machine includes: the above-described stator; a rotor; and a shaft, wherein the stator and the rotor are oppositely disposed about the shaft.

According to an exemplary embodiment, the axial-flux electric machine comprises a plurality of rotors and a plurality of stators, wherein the plurality of rotors and the plurality of stators are alternately arranged around the shaft.

According to the invention, the torque density can be improved without increasing the axial length of the motor, so that the motor is more efficient and compact, the mounting precision and the firmness can be ensured by utilizing the mature PCB embedding technology, the mass production is more facilitated, and the cost is reduced.

Drawings

Exemplary embodiments of the present application will be described in detail below with reference to the attached drawings, it being understood that the following description of the embodiments is intended to be illustrative of the present application and not limiting of the scope of the present application, and in which:

fig. 1 illustrates an exploded perspective view of an axial-flux electric machine according to an exemplary embodiment of the present invention;

FIG. 2 shows a perspective view of the stator shown in FIG. 1; and

fig. 3 shows a cross-sectional view of the axial-flux electric machine shown in fig. 1 in an assembled state.

Detailed Description

Preferred embodiments of the present application are described in detail below with reference to examples. However, it should be understood by those skilled in the art that these exemplary embodiments are not meant to limit the present application in any way. Furthermore, the features in the embodiments of the present application may be combined with each other without conflict. In the drawings, other components have been omitted for the sake of brevity, but this does not indicate that the axial-flux machine and stator of the present application may not include other components. It should be understood that the size, proportion and number of elements in the drawings are not intended to limit the present application.

As shown in fig. 1, the motor 100 includes a stator 110, a rotor 120, and a shaft 150, and the stator 110 and the rotor 120 are oppositely disposed around the shaft 150. When the stator 110 is energized to rotate the rotor 120 with the shaft 150, the shaft 150 outputs power to the outside. In addition, the motor 100 further includes

housings

130, 140 for enclosing the stator 110 and the rotor 120.

According to an exemplary embodiment, the rotor 120 comprises a disk-shaped rotor body 121 and at least one permanent magnet 122 carried on the rotor body 121 on a side of the rotor body 121 facing the stator 110. The rotor body 121 is opened at the center thereof with a rotor hole through which the shaft 150 passes. The permanent magnet 122 is flat and planar in shape, for example, a partial sector. In one example, a plurality of permanent magnets 122 are evenly distributed on the rotor body 121 at an angle around the rotor bore.

The shape, size, number and arrangement of the permanent magnets 122 may be designed in correlation with the coil design on the stator 110 (explained in detail below) to optimize the electromagnetic characteristics of the electric machine 100.

According to an exemplary embodiment, as shown in fig. 1 to 3, the stator 110 is in the form of a disk-shaped Printed Circuit Board (PCB) including a printed circuit board 111. The printed circuit board 111 includes a substrate 112 and a coil 113 disposed on a surface of the substrate 112. The substrate 112 may be an insulating plate such as a bakelite plate, a glass fiber plate, or a plastic plate. The coil 113 is formed by conductive traces on the surface of the substrate 112. For example, etching of a metal coating on the substrate 112 may be followed by the formation of various conductive traces, some of which may be formed in the form of planar coils. For example, the coils 113 are respectively formed of conductive traces extending along a two-dimensional spiral line. Such coils therefore generate a magnetic field when energized, thereby forming the stator windings of the electrical machine. Such windings are also referred to as PCB stator windings. A stator hole through which the shaft 150 passes is opened at the center of the printed circuit board 111.

The stator 110 further includes a core 114, and the core 114 is embedded in the printed circuit board 111, as shown in fig. 3. By mounting the core 114, the air gap flux density can be increased, thereby increasing the torque density of the motor. In addition, since the core 114 is embedded in the printed circuit board 111, the axial length of the stator 110 is not increased, so that the compactness of the motor can be improved. Also, the iron core 114 does not move or fall off, and stable operation of the motor can be ensured, thereby improving reliability.

As shown in fig. 3, the core 114 is disposed not to exceed the outer surface of the printed circuit board 111 where the coil 113 is disposed, i.e., the outer surface of the outermost substrate 112 of the printed circuit board 111. This allows the core 114 to be fully embedded within the printed circuit board 111 without increasing the axial length of the stator 110 at all.

With continued reference to fig. 3, the cores 114 overlap the coils 113, for example, in a one-to-one correspondence to increase the magnetic flux density. It should be noted that the cores 114 may partially or completely overlap the coils 113, and one core 114 may overlap one or more coils 113, or vice versa. The arrangement of the core 114 and the coil 113 may be adjusted according to the design of electromagnetic characteristics. For example, the printed circuit board 111 may include a plurality of coils 113, wherein each coil 113 corresponds to one iron core 114. Alternatively, at least one iron core 114 may be positioned at the center of the respective coil 113. Alternatively, at least one core 114 may be positioned off-center of the respective coil 113 for electromagnetic optimization.

According to an exemplary embodiment, the core 114 is made of a soft magnetic material, such as silicon steel, Soft Magnetic Composite (SMC), or the like.

In the structure shown in fig. 1 to 3, the printed circuit board 111 includes a plurality of substrates 112 stacked. Each substrate 112 may also be a multi-layer structure, and the core 114 may be embedded within at least one layer of the substrate 112. For example, the substrate 112 may include a base material layer, a conductive layer, a barrier layer, and the like, and the core 114 may be embedded within the base material layer.

In the structure illustrated in fig. 1 to 3, the printed circuit board 111 includes a plurality of coils, and the stator 110 includes a plurality of cores 114, and the plurality of coils 113 and the plurality of cores 114 are uniformly distributed in a corresponding manner in the circumferential direction of the printed circuit board 111. In addition, the coil 113 is disposed on one surface of the printed circuit board 111, i.e., one surface of the substrate 112. However, the coils 113 may also be disposed on both surfaces of the printed circuit board 111, that is, may be disposed on both surfaces of the substrate 112.

For a printed circuit board 111 comprising a plurality of substrates 112, the coils 113 may be disposed on one or more surfaces of at least two substrates 112. In this way, the printed circuit board 111 may have at least one layer, in particular two or more layers of coils. As shown in fig. 1 to 3, the printed circuit board 111 is constructed as a substrate provided with conductive traces on one side, in the case where one layer of the coil is provided. Alternatively, in the case of a two-layer coil, the printed circuit board 111 may be constructed as a substrate with conductive traces on both sides. In the case of more than two layers of coils, the printed circuit board 111 may be configured as a multilayer printed circuit board, i.e. consisting of two or more substrates which may optionally be provided with conductive tracks on one side, on both sides, or even be empty boards which are not provided with conductive tracks.

In the case of multilayer printed circuit boards, multiple substrates are laminated together during PCB manufacturing, particularly before the outermost conductive traces are formed, to form a unitary printed circuit board. Accordingly, the core 114 is embedded within a plurality of substrates 112, e.g., at least two substrates. As shown in fig. 3, the printed circuit board 111 includes four substrates 112, and the iron core 114 is embedded in the four substrates 112 without exceeding the surface of the printed circuit board 111 on which the coil 113 is disposed.

According to an exemplary embodiment of the present invention, the core 114 may be embedded within the printed circuit board 111 during the production of the printed circuit board 111. For example, in forming the printed circuit board 111, a blind hole or a through hole may be formed in the substrate 112, and then the shaped iron core is put in, or a flowable ferromagnetic material is injected and cured to form the iron core. Subsequently, the coil 113 may be formed on the substrate 112 and/or the multilayer substrate 112 may be laminated together to finally form the printed circuit board 111. Thus, the embedding process of the core 114 can be integrated in the PCB manufacturing process, so that the mature technology in the PCB manufacturing process can be fully utilized, the installation of the core 114 can be controlled more accurately, and mass production can be easily realized, and the cost can be saved.

In the illustrated exemplary embodiment, the electric machine 100 includes a rotor 120 and a stator 110. Alternatively, the electric machine may also include two or more rotors 120 and/or two or more stators 110. In this case, the rotors 120 and the stators 110 may be alternately arranged with each other around the shaft 150. That is, one stator 110 is always disposed between two rotors 120 that are consecutive in the extending direction of the shaft 150, and one rotor 120 is always disposed between two stators 110 that are consecutive.

According to the present application, by embedding the iron core in the printed circuit board, the axial length of the stator with PCB windings of the axial flux motor can be reduced while ensuring a high torque density. In addition, the iron core embedding can be integrated in the PCB manufacturing process, and the installation precision and firmness of the iron core can be ensured, so that the reliability can be improved, the batch production is easy, and the production cost is reduced.

The present application is described in detail above with reference to specific embodiments. However, the embodiments described above and shown in the drawings should be understood as illustrative and not limiting of the present application. It will be apparent to those skilled in the art that various changes or modifications may be made therein without departing from the spirit of the application, and these changes or modifications do not depart from the scope of the application.

Claims

1. A stator (110) for an axial-flux electric machine, comprising:

a printed circuit board (111), the printed circuit board (111) comprising a substrate (112) and a coil (113) disposed on a surface of the substrate (112), wherein the coil (113) is formed by a conductive trace on the surface of the substrate (112); and

a core (114) of a magnetic material,

characterized in that the core (114) is embedded in the printed circuit board (111).

2. The stator (110) according to claim 1, wherein the core (114) is disposed not to exceed a surface of the printed circuit board (111) on which the coil (113) is disposed.

3. The stator (110) according to claim 2, wherein the core (114) at least partially overlaps the coil (113).

4. The stator (110) according to any of claims 1 to 3, wherein the substrate (112) is a multilayer structure, the core (114) being embedded within at least one layer of the substrate (112).

5. A stator (110) according to any of claims 1-3, characterized in that the coils (113) are arranged on both surfaces of the substrate (112).

6. The stator (110) according to any one of claims 1 to 3, wherein the printed circuit board (111) comprises a plurality of coils (113) and the stator (110) comprises a plurality of cores (114), the plurality of coils (113) and the plurality of cores (114) being uniformly distributed in a corresponding manner along a circumferential direction of the printed circuit board (111).

7. The stator (110) according to any one of claims 1 to 3, wherein the printed circuit board (111) comprises a plurality of substrates (112) that are laminated.

8. The stator (110) according to claim 7, wherein the coils (113) are provided on a surface of at least two of the plurality of base plates (112), and the core (114) is embedded within the at least two of the plurality of base plates (112).

9. An axial-flux electric machine (100), wherein the axial-flux electric machine (100) comprises:

a stator (110) according to any one of claims 1 to 8;

a rotor (120); and

a shaft (150) for rotating the shaft,

wherein the stator (110) and the rotor (120) are oppositely disposed about the shaft (150).

10. Axial-flux electric machine (100) according to claim 9, comprising a plurality of rotors (120) and/or a plurality of stators (110), wherein the plurality of rotors (120) and the plurality of stators (110) are alternately arranged around the shaft (150).