Motor including wound coil and method of manufacturing the same

A motor including a wound coil includes: a stator core, a cross-section of which has a ring-shape, extending in a longitudinal direction of the motor, the stator core including a plurality of teeth in the stator core, the plurality of teeth are spaced apart from each other in a circumferential direction of the stator core, and a plurality of slots arranged between the plurality of teeth; a coil extending in a longitudinal direction of the stator core and extends into the plurality of slots; and a coupling core, which includes shoes coupled to inner ends of the plurality of teeth and which is disposed inside the stator core so as to be integrally coupled to the stator core.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Korean Patent Application No. 10-2020-0038516, filed on Mar. 30, 2020 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a motor including a wound coil and a method of manufacturing the same, and more particularly to a motor including a wound hairpin-type coil and a method of manufacturing the same.

2. Description of the Related Art

In order to meet international requirements for reduction of greenhouse gas emissions and improvement of fuel efficiency, research and development and practical realization of components associated with environment-friendly vehicles designed to generate drive force using an electric motor has been actively conducted in the field of automotive field.

Particularly, in order to realize reduction of weight and provision of sufficient internal space, technology for improving the space factor of a motor by applying a hairpin-type coil to a drive motor has been developed. In the case of application of a hairpin-type coil, although it is possible to obtain an effect of improving the efficiency and power density of a motor, there are difficulties in the manufacture and quality management thereof.

In the conventional technology, a drive motor is manufactured such that hairpins are prepared by shaping coils each having an angled cross-section into a “U” shape or a “V” shape, the hairpins are fitted into slots formed in the stator core of the motor, the ends of the hairpins are twisted, and the twisted ends of the hairpins are connected to each other through welding.

However, the conventional process has problems in which the procedure of winding the hairpins is complicated, a long time is taken for the manufacture, and the incidence of defects caused by poor welding is increased.

Although an approach to fit a wound coil into slots in a stator core has been attempted in an effort to overcome the problems, there is a problem in that the stator core interferes with shoes.

Details described as the background art are intended merely for the purpose of promoting the understanding of the background of the present invention and should not be construed as an acknowledgment of the prior art that is previously known to those of ordinary skill in the art.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a motor including a hairpin-type coil, which is continuously wound around a stator core equipped with shoes, and a method of manufacturing the motor.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a motor including a wound coil including a stator core, which has a ring-shaped cross-section and extends in a longitudinal direction of the motor and which includes therein a plurality of teeth, which are spaced apart from each other in a circumferential direction of the stator core, and a plurality of slots defined between the plurality of teeth, a coil, which extends in a longitudinal direction of the stator core and is fitted into the plurality of slots, and a coupling core, which includes shoes coupled to inner ends of the plurality of teeth and which is positioned inside the stator core so as to be integrally coupled to the stator core.

A portion of the coil may extend to an outside of the stator core in the longitudinal direction of the stator core, and the coil may be fitted into the stator core such that the coil is bent at an outside of the stator core and extends into the same slot or an adjacent slot.

Each of the shoes of the coupling core may extend from an inner end of a corresponding tooth to insides of the slots.

The coupling core may include a plurality of shoes, which extend in the longitudinal direction of the stator core of the coupling core and are arranged in a circumferential direction of the coupling core.

Each of the plurality of shoes may be connected to an adjacent shoe in a partial region or an entire region thereof in the longitudinal direction of the stator core.

The coupling core may include a connector adapted to connect adjacent shoes to each other in a circumferential direction of the coupling core, the connector being depressed radially inwards or outwards so as to have a thickness smaller than that of the shoes.

The coupling core may include a plurality of shoes, which extend in the longitudinal direction of the stator core, the connector may be formed only in a partial region of a longitudinal boundary between adjacent shoes, among the plurality of shoes, and the adjacent shoes may be spaced apart from each other in a circumferential direction of the coupling core in the remaining region of the longitudinal boundary.

Each of the shoes may include a coupling protrusion, which projects toward a corresponding one of the plurality of teeth, and each of the plurality of teeth may include a coupling groove, which is depressed radially inwards, such that the coupling protrusion of the shoe is fitted into and coupled into the coupling groove in the tooth.

The coupling core may extend in the longitudinal direction of the stator core, and may be coupled to the stator core only in a partial region thereof in the longitudinal direction of the stator core.

The inner ends of the plurality of teeth may extend longer in a radially inward direction of the stator core in a region of the stator core in which the coupling core is not coupled to the stator core than in a remaining region of the stator core in which the coupling core is coupled to the stator core.

The coupling core may include a plurality of shoes, which are continuously arranged in a circumferential direction of the coupling core so as to define a ring shape.

In accordance with another aspect of the present invention, there is provided a method of manufacturing the motor including a wound coil including preparing the stator core including the plurality of teeth and the plurality of slots defined between the plurality of teeth, fitting the continuously wound coil into the plurality of slots in the stator core, and integrally coupling the coupling core in the stator core by coupling the shoes to the inner ends of the plurality of teeth.

In the integral coupling of the coupling core, the coupling core may be fitted into the stator core in the state in which the stator core and the coupling core have different temperatures.

Each of the shoes may include a coupling protrusion, which projects toward a corresponding one of the plurality of teeth, and each of the plurality of teeth may include a coupling groove, which is depressed radially inwards. In the integral coupling of the coupling core, the coupling protrusions of the shoes may be fitted into and coupled to the coupling grooves in the teeth in the state in which the stator core is heated or the coupling core is cooled.

In the fitting of the continuously wound coil, the continuously wound coil may be fitted into the plurality of slots in the state in which the stator core is heated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Specific structural and functional descriptions of embodiments of the present invention disclosed herein are only for illustrative purposes of the embodiments of the present invention. The present invention may be embodied in many different forms without departing from the spirit or significant characteristics of the present invention. Therefore, the embodiments of the present invention are disclosed only for illustrative purposes and should not be construed as limiting the present invention.

Reference will now be made in detail to various embodiments of the present invention, specific examples of which are illustrated in the accompanying drawings and described below, since the embodiments of the present invention can be variously modified in many different forms. While the present invention will be described in conjunction with exemplary embodiments thereof, it is to be understood that the present description is not intended to limit the present invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Throughout the drawings, the same reference numerals will refer to the same or like parts.

FIG.1is a cross-sectional view of a motor including a wound coil20according to an embodiment of the present invention.

Referring toFIG.1, the motor including a wound coil20according to an embodiment of the present invention includes a stator core10, which is configured to have a ring-shaped cross-section and to extend longitudinally and which includes therein a plurality of teeth12, which are circumferentially spaced apart from each other so as to define a plurality of slots13between the plurality of teeth12, a coil20, which is disposed in the plurality of slots13and extends in the longitudinal direction of the stator core10so as to be wound around the stator core10, and a coupling core30, which includes shoes31coupled to the inner ends of the plurality of teeth12and which is disposed inside the stator core10and is integrally coupled to the stator core10.

Although the motor including the wound coil20may be applied to a motor for driving a vehicle, the present invention is not limited thereto.

The stator core10refers to a stator core of the motor, in which the plurality of teeth12extend longitudinally along the inner side of a ring-shaped yoke11. The plurality of teeth12may be arranged so as to be spaced apart from each other, and the slots13may be formed between the plurality of teeth12.

In another embodiment, the stator core10may be constructed such that the yoke11formed at the outer sides of the teeth12are split into a plurality of yoke sectors. In other words, split-type stator cores10may be fitted between the coil20from the outside such that the coil20is wound around the stator core10.

The teeth12coupled to the yokes11may be fitted between the coil20from the outside, whereby the distance between adjacent teeth12is decreased. A support ring may surround the outer surface of the stator core10in the state in which the split-type cores10are coupled to each other.

The coil20may be configured to have not only a circular cross-section but also an angled cross-section. In other words, the coil20may be a hairpin-type coil20, which has a polygonal cross-section such as a rectangular cross-section and extends longitudinally.

The coil20may be fitted into the plurality of slots13in the state of extending in the longitudinal direction of the stator core10so as to be wound around the stator coil10.

In a conventional technology, about 100 to 150 linear coil segments, each of which extends linearly, or about 100 to 150 hairpin coil segments, each of which is bent into a U shape (or a V shape), are fitted into a plurality of slots13, and then the coil segments are twisted or welded, whereby the coil is wound around the stator core.

According to the present invention, hairpin-type coils20, which are continuously connected to each other, are fitted into the slots13in the stator core10such that the coil20is wound around the stator core10. Accordingly, it is possible to omit an additional process such as twisting or welding.

The coupling core30may include shoes31, which are respectively coupled to the inner ends of the teeth12included in the stator core10. Each of the shoes31may be coupled to the inner end of one of the teeth12and may extend circumferentially outwards from the corresponding tooth12to the inside of the slot13.

Specifically, the coupling core30is manufactured separately from the stator core10, the continuous coil20is inserted into the stator core10, and the coupling core30is integrally coupled to the inner side of the stator core10.

Accordingly, since the continuous coil is inserted into the stator core10, it is possible to omit a welding process and thus to offer an effect of decreasing a defective fraction caused by poor welding.

Furthermore, since the coupling core30including the shoes31is inserted into the stator core10, there are effects of improving performance of reducing NVH (noise, vibration and harshness) and of reducing torque ripple and cogging torque of a motor.

In addition, since the capacitance between a rotor core and the coil20is decreased, there is an effect of lowering the shaft voltage in a shaft coupled to the rotor core.

The coil20may be inserted into the stator core10such that a portion of the coil20extends to the outside of the stator core10in the longitudinal direction of the stator core10and such that the coil20is bent at the outside of the stator core10and continuously extends into the same slot13or an adjacent slot13.

The coil20may extend in the longitudinal direction of the stator core10and then in upward and downward directions of the stator core10. The coil20may be bent at the outer side of the stator core10, and may extend into the same slot13or an adjacent slot13.

The coil20may be wound around the stator core10in such a manner as to be fitted into a single slot13in the radial direction of the stator core10four times, six times or eight times and then to extend into an adjacent slot13.

In other words, unlike a conventional technology, in which coil segments are fitted into the stator core10and are connected to each other through welding, the coil20according to the present invention may be fitted into the stator core10in the continuous state.

Each of the shoes31of the coupling core30may extend from the inner end of the tooth12to the inside of the slot13.

Each shoe31may extend in the circumferential direction of the coupling core30or the stator core10. In other words, the shoe31may extend in opposite circumferential directions from the inner end of the tooth12to the inside of the slot13. Accordingly, the shoe31may extend into the slot13, and may thus cover a portion of the inner side of the coil20.

The coupling core30may include a plurality of shoes31, which extend in the longitudinal direction of the stator core10. The plurality of shoes31may be arranged in the circumferential direction of the coupling core30.

In an embodiment, the coupling core30may be constructed such that a plurality of shoes31are continuously connected to each other so as to define a ring-shaped cross-section and to extend in the longitudinal direction of the stator core10. The number of shoes31may be the same as the number of teeth12included in the stator core10.

In another embodiment, a plurality of coupling cores30may be coupled to the stator core10in which each of the coupling cores30is composed of a plurality of shoes31, which are connected to each other so as to define an arched cross-section. For easy coupling, a continuous ring-shaped coupling core may be divided into two or three coupling core sectors30, and the coupling core sectors30may be coupled to the stator core10.

FIGS.2to5are views illustrating coupling cores30in a spread state according to various embodiments of the present invention.

Specifically,FIGS.2to5are plan views illustrating the spread state of a coupling core30, which is one of coupling core sectors prepared by longitudinally cutting an integral coupling core30or of a coupling core30, which is originally manufactured so as to have an arched cross-section.

Referring again toFIGS.2to5, adjacent shoes among the plurality of shoes31included in the coupling core30may be circumferentially connected to each other in a partial section or the entire section of the longitudinal boundary between the adjacent shoes31.

As described later, each of the plurality of shoes31may be connected to an adjacent shoe31via a connector32.

In an embodiment, adjacent shoes31may be connected to each other only in a partial section of the longitudinal boundary therebetween.

Specifically, as illustrated inFIGS.2to5, adjacent shoes31may be connected to each other at the center of the longitudinal boundary therebetween (seeFIG.2), or at one end of the longitudinal boundary therebetween (seeFIG.3). Furthermore, adjacent shoes31may be connected to each other at the center and at one end of the longitudinal boundary therebetween (seeFIG.4), or at multiple points, that is, at one end, at the center, and at the other end of the longitudinal boundary therebetween (seeFIG.5).

In other words, since adjacent shoes31are connected to each other in a partial section of the longitudinal boundary therebetween, there is an effect of allowing the coupling core30to be easily coupled to the stator core10. Furthermore, since the adjacent shoes31are separated from each other in the remaining section of the longitudinal boundary therebetween, there is an effect of reducing leakage of magnetic flux.

In another embodiment, adjacent shoes31may be connected to each other in the entire section of the longitudinal boundary therebetween.

The coupling core30may include the connectors32, adapted to connect adjacent shoes31to each other in a circumferential direction of the coupling core. Each of the connectors32may be depressed radially inwards or outwards so as to have a thickness smaller than the shoe31.

The connector32may be configured to have the form of a bridge connecting adjacent shoes31to each other and to cover the slot13between the teeth12coupled to the adjacent shoes31so as to close the space in the slot13.

Particularly, the connector32may be depressed radially inwards from the outer surface thereof so as to have a thickness smaller than the shoe31. Alternatively, the connector32may be depressed radially outwards from the inner surface thereof.

Accordingly, there is an effect of opening the region of the slot13that is shielded by the connector32. The connector32may have a thickness as small as possible, as long as the connector32is capable of maintaining a desired rigidity, for example, a thickness of about 0.3-0.6 mm.

The coupling core30may include a plurality of shoes31, which extend in the longitudinal direction of the stator core10. The connector32may be formed only in a partial section of the longitudinal boundary between adjacent shoes31such that the adjacent shoes31are spaced apart from each other in the remaining section of the longitudinal boundary.

In other words, the connector32may connect adjacent shoes31at a portion such as one end or the center of the stator core10or the coupling core30such that the adjacent shoes31are spaced apart from each other at the remaining portion of the coupling core30, as illustrated inFIGS.2to5.

In an embodiment, the shoe31may be provided with a coupling protrusion33, which projects toward the tooth12, and the tooth12may be provided with a coupling groove14, which is depressed radially inwards. Accordingly, the coupling protrusion33of the shoe31may be fitted into the coupling groove14in the tooth12and may be thus coupled thereto.

Specifically, each of the coupling protrusion33and the coupling groove14may be configured to have a semicircular or circular section. The coupling protrusion33may be fitted into and coupled into the coupling groove14in an interference-fitting manner or in a heat-shrink-fitting manner.

In another embodiment, the tooth12may be provided with the coupling protrusion33, and the shoe31may be provided with the coupling groove14. Accordingly, the coupling protrusion33on the tooth12may be fitted into and coupled to the coupling groove14in the shoe31.

In a further embodiment, the shoe31and the tooth12may be coupled to each other through bonding using an adhesive or the like.

FIG.6is a plan view illustrating the state in which the stator core10including the coupling core coupled thereto according to the present invention is spread into a flat shape.

Referring toFIG.6, the coupling core30may extend in the longitudinal direction of the stator core10, and may be coupled to the stator core10only in a partial region in the longitudinal direction of the stator core10.

Specifically, as illustrated inFIG.6, the coupling core30may be coupled to the inner side of the stator core10only in a partial region (an overlapping region A) in the longitudinal direction of the stator core10, and may be separated therefrom in the remaining region (overlapping region B).

Because the coupling core30is not coupled to the stator core10in the overlapping region B, the shoes31are not coupled to the plurality of teeth12in the overlapping region B but are coupled to the plurality of teeth12only in the overlapping region A, with the result that adjacent shoes31are connected to each other via the connectors32in the overlapping region A.

The overlapping region A may be larger than the overlapping region B. For example, based on the length or the area of the inner circumferential surface of the stator core10, the overlapping region A may be set to be 90% or higher, and the overlapping region B may be set to be 10% or lower.

FIG.7is a cross-sectional view of the stator core10including the coupling core coupled thereto according to an embodiment of the present invention.

Referring toFIG.7, the inner end of the tooth12may extend longer in the inward direction of the stator core10in the region of the stator core10in which the coupling core30is not coupled to the stator core10than in the remaining region of the stator core10, in which the coupling core30is coupled to the stator core10.

Specifically, the inner end of the tooth12may extend longer radially inwards in the overlapping region B, in which the coupling core30is not coupled to the stator core10, than in the overlapping region A.

Because the shoe31is coupled to the inner side of the tooth12in the overlapping region A, the inner side of the tooth12may extend further radially inwards to an extent corresponding to the thickness of the shoe31when the coupling core30is coupled to the stator core10. Meanwhile, in the overlapping B in which the coupling core30is not coupled to the stator core10, the inner end of the tooth12may extend further radially inwards to an extent corresponding to the thickness of the shoe31.

Accordingly, the inner ends of the plurality of teeth12or the plurality of shoes31in the overlapping region A, in which the coupling core30is coupled to the stator core10, and in the overlapping region B, in which the coupling core30is not coupled to the stator core10, may the same radial distance from the center of the stator core10.

In an embodiment, the coupling core30may be composed of a plurality of shoes31, which are continuously arranged in the circumferential direction of the coupling core so as to define a ring shape, which is continuous in the circumferential direction of the coupling core.

Specifically, the coupling core30may be constructed such that a plurality of shoes31are continuously connected to each other in the circumferential direction of the coupling core and the two outermost shoes31are connected to each other so as to define a ring shape. Accordingly, the ring-shaped coupling core30may be fitted into the stator core10all at once.

In another embodiment, the coupling core30may be divided into a plurality of cores in the circumferential direction of the coupling core. In other words, each of the cores30may have an arched cross-section, which is a portion of a ring-shaped cross-section. The plurality of coupling cores30may be separately coupled to the stator core10. The plurality of coupling cores30may be arranged on the stator cores10in the circumferential direction of the stator cores, and the facing ends of adjacent stator cores10may be connected to each other.

FIG.8is a flowchart illustrating a method of manufacturing the motor including a wound coil20according to an embodiment of the present invention.

Referring toFIG.8, the method of manufacturing the motor including a wound coil20according to an embodiment of the present invention may include an operation (S100) of preparing the stator core10including a plurality of teeth12and a plurality of slots13defined between the plurality of teeth12, an operation (S200) of fitting the continuously wound coil20into the plurality of slots13, and an operation (S300) of integrally coupling the coupling core30to the inner side of the stator core10by coupling the shoes31to the inner ends of the teeth12.

In the operation (S100) of preparing the stator core10, the stator core10is formed through a separate process. At this time, the stator core10is formed such that a plurality of teeth12are formed in the inner circumferential surface of the yoke11so as to be spaced apart from each other in the circumferential direction of the stator core, thereby creating a plurality of slots13between the plurality of teeth12. Here, the teeth12of the stator core10may not be provided with the shoes31individually extending in the circumferential direction of the stator core.

In the operation (S200) of fitting the coil20, the continuously wound coil20may be fitted into the plurality of slots13in the stator core10.

The coil20, which extends in the longitudinal direction of the stator core, may be bent at the two ends of the stator core10and then extend in the opposite direction in a zigzag fashion. Here, the coil20, which is of a hairpin type having a rectangular cross-section, may be fitted into the plurality of slots13. In other words, the plurality of teeth12of the stator core10may be fitted into the wound coil20such that the coil20is wound around the stator core10.

In the operation (S300) of integrally coupling the coupling core30, the coupling core30may be coupled to the inner circumferential surface of the stator core10in the state in which the coil20is fitted into the plurality of slots13.

Specifically, in the operation (S300) of integrally coupling the coupling core30, the coupling core30may be fitted into the stator core10in the state in which the stator core10and the coupling core30have different temperatures.

The coupling core30, in which adjacent shoes31are connected to each other so as to define a ring-shaped cross-section, may be fitted into the stator core10in the axial direction (the longitudinal direction). To this end, the stator core10and the coupling core30may be heated or cooled to different temperatures, and the coupling core30may be fitted into the stator core10.

In an embodiment, the stator core10, which is externally positioned, may be heated to a relatively high temperature, or the coupling core30, which is internally positioned, may be cooled to a relatively low temperature.

Specifically, the coupling core30may be fitted into the stator core10in the longitudinal direction in the state in which the stator core10is heated and expanded, and then the stator core10may be cooled, thereby coupling the coupling core30to the stator core10.

Alternatively, the coupling core30may be fitted into the stator core10in the longitudinal direction in the state in which the coupling core30is cooled and shrunk, and then the coupling core30may be heated, thereby coupling the coupling core30to the stator core10.

Here, the stator core10and the coupling core30may be made of the same material, and may thus have the same coefficient of thermal expansion.

Specifically, the shoe31may be provided with the coupling protrusion33, which projects toward the tooth12, and the tooth12may be provided with the coupling groove14, which is depressed radially inwards. In the operation (S300) of integrally coupling the coupling core30, the coupling protrusion33of the shoe31may be fitted into the coupling groove14in the tooth12in the state in which the stator core10is heated or the coupling core30is cooled.

In the case in which the coupling core30is fitted into the stator core10in the state in which the stator core10is heated and expanded and the coupling core30is cooled and shrunk, the coupling groove14may be formed in the tooth12of the stator core10, and the coupling protrusion33may be formed on the shoe31of the coupling core30.

Accordingly, the coupling protrusion33may be easily fitted into the coupling groove14in the state in which the coupling groove14is expanded or in which the coupling protrusion33is shrunk. Subsequently, the stator core10may be cooled or the coupling core30may be heated, thereby preventing the coupling protrusion33from escaping from the coupling groove14.

In the operation (S200) of fitting the coil20, the continuously wound coil20may be fitted into the plurality of slots in the state in which the stator core10is heated.

Because the stator coil20is heated and expanded and the slots13defined between the plurality of teeth12are thus expanded, the wound coil20may be easily fitted into the slots13.

In another embodiment, the coil20may also be fitted into the slots13so as to be wound around the stator core10in the state in which the coil20is cooled and shrunk.

In a further embodiment, in the operation (S100) of preparing the stator core10, a split-type stator core10, in which the plurality of teeth12and the yoke11coupled to the outer surfaces of the plurality of teeth12are split into a plurality of stator core sectors, may be prepared, and the plurality of stator core sectors10may be arranged in the circumferential direction of the stator core, thereby completing the stator core10.

In the operation (S200) of fitting the coil20, the coil20may be fitted into the plurality of slots13defined between the plurality of teeth12by fitting the split-type stator core10into the coil20from the outside of the coil20.

As is apparent from the above description, in the motor including a wound motor and the method of manufacturing the same according to the present invention, since the continuously wound coil is fitted into the stator core, it is possible to omit a welding process and thus to convey an effect of decreasing a defective fraction caused by poor welding.

Furthermore, since the coupling core including the shoes is inserted into the stator core, there are effects of improving performance of reducing NVH (noise, vibration and harshness) and of reducing torque ripple and cogging torque of the motor.