CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application of International Patent Application No. PCT/JP2017/028371 filed on Aug. 4, 2017, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a rotor, a motor, a fan, an air conditioning apparatus, and a manufacturing method of a rotor.

BACKGROUND

Conventionally, there is known a rotor of a motor in which a rotor core is divided into an inner rotor core and an outer rotor core, and a space therebetween is filled with resin (see, e.g., Patent Literature 1).

PATENT LITERATURE

Patent Literature 1: Japanese Patent Application Publication No. 2004-297935 (see FIG. 2)

However, in the configuration in which the space between the inner rotor core and the outer rotor core is filled with resin as described above, since the resin portion is small, the adjustment range of the resonant frequency of the rotor is narrow. Thus, when the motor is used in a fan, it is difficult to reduce torsional resonance of the motor and impeller or resonance of a unit including the fan, and noise can occur.

SUMMARY

The present invention has been made to solve the above problem, and is intended to provide a rotor, a motor, a fan, an air conditioning apparatus, and a manufacturing method of a rotor capable of reducing noise.

A rotor according to the present invention includes: a shaft; a rotor core having an annular shape and surrounding the shaft from outside in a radial direction about a center axis line of the shaft so as to leave a space therebetween; a magnet embedded in the rotor core; and a connecting portion disposed between the shaft and the rotor core and formed of a nonmagnetic material.

Another rotor according to the present invention includes: a shaft; a rotor core having an annular shape and surrounding the shaft from outside in a radial direction about a center axis line of the shaft so as to leave a space therebetween; a magnet mounted to the rotor core; and a connecting portion disposed between the shaft and the rotor core and formed of a nonmagnetic material. The magnet forms a first magnetic pole, and a part of the rotor core forms a second magnetic pole.

According to the present invention, since a connecting portion formed of a nonmagnetic material is disposed between a shaft and a rotor core, it is possible to adjust a resonant frequency of the rotor by changing the shape and size of the connecting portion, thereby reducing noise. Also, since the rotor core and shaft are separated by the connecting portion, it is possible to reduce magnetic flux leakage from the rotor core to the shaft, improving the performance of a motor.

