PRIORITY STATEMENT

This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/CN2019/088381 which has an International filing date of May 24, 2019, which designated the United States of America 2020, the entire contents of each of which are hereby incorporated herein by reference.

FIELD

The present application generally relates to the field of electric motors, in particular to an electric motor, a laminated iron core, and a manufacturing method therefor.

BACKGROUND

For electronic products such as electric motors and power transformers, copper wires are usually wound on a soft ferromagnetic component, which has a high magnetic permeability relative to air to increase magnetic flux, thereby achieving a high energy density (high strength) and efficiency.

As shown inFIG. 1, in order to reduce eddy current losses caused by the fluctuating magnetic field, a laminated iron core10is made by laminating silicon steel sheets covered with an insulation film, and laminated cores are usually used for power transformers and electric motors. Among them, the insulation film functions as a protective screen against eddy currents, so that eddy currents flow only in a finite closed loop, that is, in the thickness direction of each lamination shown inFIG. 1, wherein the arrow inFIG. 1indicates the eddy current flow direction C1, and the arrow S1perpendicular to the eddy current direction C1indicates the direction of the magnetic field.FIG. 1also shows a block iron core20, which does not have the sheet lamination structure of a laminated iron core and in which eddy currents are also confined to a closed loop. The eddy current direction is indicated by the direction C2, and the arrow S2perpendicular to the eddy current direction C2indicates the direction of the magnetic field. Specifically, each lamination of the laminated iron core10has a thickness of around 0.3 mm. Since the current of an eddy current closed loop is proportional to the cross-sectional area of the sheet (and its resistance is inversely proportional to the cross-sectional area), this can reduce eddy currents to a very low level. Generally, the higher the operating frequency, the smaller the single-layer thickness of the laminated iron core10is.

In order to manufacture the laminated structure of the laminated iron core10as shown inFIG. 1, a cold-rolled silicon steel sheet is punched and assembled according to a laminated structure, which not only imposes stricter requirements for the manufacture of a silicon steel sheet structure, but also makes the assembly of the laminated structure of the entire laminated iron core10very complicated. In order to achieve optimal performance and miniaturization of components, the manufacture of laminated iron cores has become increasingly complicated, which poses the biggest problem and limitation to be addressed in the manufacture of laminated iron cores.

An iron core may also be made of epoxy resin in which soft magnetic particles are added, wherein the epoxy resin functions as an electrical isolation layer, making it possible to provide a magnetic core with high resistance and therefore reduced eddy current losses. However, the main shortcomings of the above-described soft magnetic composite iron core are its relatively low magnetic permeability (only 10% to 20% of that of a silicon steel material) and its low magnetic flux density.

SUMMARY

Additive manufacturing technology is also used to manufacture custom iron cores and iron cores having complex shapes to optimize magnetic properties and achieve miniaturization of original parts. However, the inventors have discovered that the existing additive manufacturing technology is only applicable to the manufacture of block magnetic cores, and is subject to considerable eddy current losses. The inventors have discovered that such eddy current losses will not only reduce the component efficiency, and heat generated by eddy currents can significantly impair the component performance, which will also hinder system miniaturization.

A first embodiment of the present invention provides a method for manufacturing a laminated iron core, wherein the manufacturing method is executed in an additive manufacturing printing apparatus and comprises the following steps: S1: injecting an inert gas into the additive manufacturing printing apparatus, spreading a silicon steel metal particle in a molding cylinder in the additive manufacturing printing apparatus, and performing laser scanning on the silicon steel metal particle, so that the silicon steel metal particle is melted layer by layer into at least one silicon steel metal layer; and S2: continuously spreading the silicon steel metal particle in the molding cylinder in the additive manufacturing printing apparatus, and stopping performing the laser scanning on the silicon steel metal particle or reducing a laser power for performing the laser scanning, so that an insulation layer in which the silicon steel metal particle is not fully melted is formed, step S1 and step S2 being alternately performed until a laminated iron core comprising a plurality of alternating silicon steel metal layers and the insulation layer is formed.

A second embodiment of the present invention provides a laminated iron core, wherein the laminated iron core is manufactured using the method for manufacturing a laminated iron core according to the first embodiment of the present invention.

A third embodiment of the present invention provides an electric motor comprising the laminated iron core manufactured using the method for manufacturing a laminated iron core according to the first embodiment of the present invention.

