MOTOR

A motor comprises a stator having a plurality of split cores coupled to one another, each split core including a tooth part and a yoke part; and a housing accommodating the stator in the housing. The motor can secure assembly stability while reducing friction torque due to the magnetic flux leaking from the stator to the housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No. 10-2023-0026355, filed on Feb. 27, 2023, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Technical Field

Some embodiments of the present disclosure generally relate to a motor and, more specifically, to a motor capable of reducing friction torque due to the magnetic flux leaking to a housing from a stator and securing assembly stability.

Description of Related Art

In general, a motor includes a coil-wound stator and a rotor coupled with a permanent magnet to generate rotational power. The rotor is coupled to a rotation shaft, and the stator is fixed to the inner surface of the housing, outside of the rotor.

The motor has a structure of rotating the rotor by the magnetic force generated as electricity is supplied to the coil of the stator. The magnetic force generated from the coil may leak to the housing, acting as friction torque.

BRIEF SUMMARY

Various embodiments of the present disclosure have been conceived and relate to a motor capable of reducing friction torque due to the magnetic flux leaking to the housing from the stator and securing assembly stability.

According to some embodiments of the present disclosure, there may be provided a motor comprising a stator formed by coupling a plurality of split cores including a tooth part and a yoke part and a housing receiving the stator and having a plurality of inner grooves formed in an inner surface contacting the yoke part.

According to certain embodiments of the present disclosure, there may be provided a motor comprising a stator formed by coupling a plurality of split cores including a tooth part and a yoke part and having one or more outer grooves formed in an outer surface of the yoke part and a housing receiving the stator.

According to some embodiments of the present disclosure, it is possible to secure assembly stability while reducing friction torque due to the magnetic flux leaking from the stator to the housing.

DETAILED DESCRIPTION

FIG.1is a front view illustrating a motor according to an present embodiment of the present disclosure.FIG.2is enlarged views illustrating a motor according to embodiments of the present disclosure.FIG.3is cross-sectional views illustrating a motor according to embodiments of the present disclosure.FIG.4is an enlarged view illustrating a motor according to an embodiment of the present disclosure.FIG.5is an enlarged view illustrating a motor according to an embodiment of the present disclosure.FIG.6is enlarged views illustrating a motor according to embodiments of the present disclosure.FIG.7is enlarged views illustrating a motor according to embodiments of the present disclosure.

Referring toFIG.1, a motor100according to the present embodiments includes a stator110formed by coupling a plurality of split cores111including a tooth part112and a yoke part113and a housing120receiving the stator110and having a plurality of inner grooves121formed in an inner surface contacting the yoke part113.

The motor100according to the present embodiments includes a stator110and a housing120. A coil is wound around the tooth part112of the stator110, and the rotor is rotated by a magnetic force generated by supplying a current to the coil. The rotor is positioned inside the stator110, and is omitted for convenience of illustration. The rotor is provided with a plurality of permanent magnets, and the rotor is coupled to a rotation shaft. Accordingly, the rotor is rotated by a magnetic force generated from the coil to which the current is applied.

The stator110is formed by coupling the plurality of split cores111, and each of the split cores111includes a tooth part112and a yoke part113. The yoke part113has protrusions and recesses to be engaged with and coupled to another yoke part113, and the split cores111are coupled in the circumferential direction to form one plate. A plurality of plates are stacked to form the stator110, and a coil is wound around the stacked tooth parts112. The yoke part113is provided with a notch114for fixing the split core111to a jig when the split cores111are coupled to each other, which is described below.

The housing120receives the stator110, and a rotor positioned inside the stator110is also positioned inside the housing120. The rotation shaft to which the rotor is coupled may be rotatably coupled to the housing120by, e.g., a bearing. According to an embodiment, the housing120may be formed of steel.

In the stator110, the outer surface of the yoke part113is supported on the inner surface of the housing120and is coupled to the housing120. According to an embodiment, the housing120and the stator110may be coupled by press-fitting. A plurality of inner grooves121are formed in the inner surface of the housing120on which the yoke part113is supported. As the inner grooves121are formed in the housing120, the contact area between the housing120and the stator110is reduced.

As the contact area between the housing120and the stator110is reduced, the magnetic flux that leaks to the housing120when the current is applied to the coil may be reduced, and the friction torque may be reduced. The housing may be formed of aluminum, which is a non-magnetic material, to reduce friction torque, but aluminum has the high cost and thus increases the manufacturing cost of the motor. The housing and the stator may be bonded with a large assembly gap while forming the housing of steel, but this way may suffer from reduced assembly rigidity. However, according to some embodiments of the present disclosure, it is possible to reduce the leaking magnetic flux and friction torque by reducing the contact area between the housing120and the stator110even when the housing120is formed of steel which is relatively cheap. Further, since there is no increase in the assembly gap between the housing120and the stator110and no bonding therebetween, assembly stability is not deteriorated.

According to an embodiment, the inner grooves121may be arranged in a circumferential direction in the inner surface of the housing120. According to an embodiment, as illustrated inFIG.2(A), the inner grooves121may be arranged adjacent to each other in the circumferential direction. According to an embodiment, as illustrated inFIG.2(B), the inner grooves121may be arranged to be spaced apart in the circumferential direction. Considering the amount of magnetic flux leaking to the housing120and the assembly stability of the housing120and the stator110, the circumferential width of the inner groove121and the circumferential interval between inner grooves121may be adjusted.

According to an embodiment, as illustrated inFIG.3(A), each of the inner grooves121may be formed from one end to the other end in the axial direction of the housing120. The inner groove121is parallel to the axial direction and may be formed from one end to the other end of the housing120in the axial direction. Alternatively, the inner groove121is not parallel to the axial direction and may be formed from one end to the other end of the housing120in the axial direction. For example, the inner groove121may be formed in a spiral shape.

According to an embodiment, as illustrated inFIG.3(B), the inner grooves121may be arranged to be spaced apart in the axial direction. The interval between the inner grooves121arranged in the axial direction may be constant or may not be constant. Considering the amount of magnetic flux leaking to the housing120and the assembly stability of the housing120and the stator110, the axial length of the inner groove121and the axial interval between inner grooves121may be adjusted.

According to an embodiment, as illustrated inFIG.2, the inner groove121may have a triangular groove shape. According to an embodiment, as illustrated inFIG.4, the inner groove121may have a rectangular groove shape. According to an embodiment, the inner groove121may have a polygonal groove shape. The shape of the inner groove121is not particularly limited, and may be appropriately selected in consideration of the leaking flux amount and assembly stability.

Referring toFIG.5, according to an embodiment, one or more outer grooves511may be formed in the outer surface of the yoke part113. In other words, the contact area between the housing120and the stator110may be reduced not only by forming the inner grooves121in the inner surface of the housing120, but also by forming the outer grooves511in the outer surface of the yoke part113. One or more outer grooves511may be formed in the outer surface of the yoke part113for each split core111forming the stator110.

The yoke part113is provided with a notch114for fixing the split core111to the jig when the split core111is coupled, and the contact area between the housing120and the stator110may be reduced by further forming the outer grooves511in addition to the notch114. According to an embodiment, the notch114may be formed in the central portion of the outer surface of the yoke part113, and the outer grooves511may be provided on two opposite sides of the notch114. In other words, two outer grooves511may be formed at two opposite ends of the yoke part113with the notch114interposed therebetween in one split core111.

According to an embodiment, the inner groove121and the outer groove511may be provided not to overlap in the radial direction. In other words, as illustrated inFIG.5, the inner groove121of the housing120and the outer groove511of the stator110may be positioned at different positions in the circumferential direction. By providing the inner groove121and the outer groove511at different positions in the circumferential direction, the contact area between the housing120and the stator110may be more effectively reduced.

According to an embodiment, as illustrated inFIG.5, the inner groove121may have a triangular groove shape. According to an embodiment, the inner groove121may have a rectangular groove shape. According to an embodiment, the inner groove121may have a polygonal groove shape. The shape of the outer groove511is not particularly limited, and may be appropriately selected in consideration of the leaking flux amount and assembly stability.

Referring toFIG.6, according to an embodiment, a chamfered portion611may be formed on the outer surface of the yoke part113. The chamfered portion611is formed, two opposite ends of the yoke part113are supported by the housing120, and the portion between the two opposite portions supported by the housing120are spaced apart from the housing120, so that the contact area between the housing120and the stator110is reduced. The notch114may be formed in the chamfered portion611. The chamfered portion611may be formed as a flat surface as illustrated in the drawings, or may be formed with a curvature lower than that of the inner surface of the housing120.

Referring toFIG.7, a motor700according to the present embodiments includes a stator110formed by coupling a plurality of split cores111including a tooth part112and a yoke part113and having one or more outer grooves511formed in an outer surface of the yoke part113and a housing120receiving the stator110. Since the contact area between the housing120and the stator110is reduced by the outer grooves511, even if the housing120is formed of a magnetic material, the leaking magnetic flux to the housing120is reduced, and thus the friction torque is reduced. Further, since there is no increase in the assembly gap between the housing120and the stator110and no bonding therebetween, assembly stability is not deteriorated. The same reference numerals are used to denote the same elements as those in the embodiment shown inFIG.1, with the description simplified.

According to an embodiment, the housing120is formed of steel. According to an embodiment, the housing120and the stator110are coupled by press-fitting.

According to an embodiment, the outer groove511has a triangular groove or a rectangular groove shape.

According to an embodiment, the outer groove511has a polygonal groove shape.

According to an embodiment, the notch114is formed in the center of the outer surface of the yoke part113, and the outer grooves511are provided on two opposite sides of the notch114.

According to an embodiment, a plurality of inner grooves121are formed in the inner surface of the housing120contacting the yoke part113.

According to an embodiment, the inner groove121and the outer groove511are provided not to overlap in the radial direction.

By the shapes and configuration of the motor described above, it is possible to secure assembly stability while reducing friction torque due to the magnetic flux leaking from the stator to the housing.

Further, the motor according to the present embodiments may be a motor for a vehicle, and more specifically, may be a motor of a power-assisted steering device.