Abstract: A bearing 41 of a support portion 4 for rotatably supporting a shaft 11 of a rotating body 10 to be measured with respect to the magnitude of unbalance thereof is formed into a hollow U-shape and has formed therein an injection port 41b for injecting a gas towards the shaft. As the shaft can be supported and floats without making contact with the bearing by virtue of the gas injected from the injection port, the friction can be made small and, hence, a change in rotational speed can be made small. The number and position of the injection ports are determined as required.

Abstract: It is an object of the present invention to provide a method of manufacturing a rotor for an electric motor, in which displacement of the center of gravity is prevented. According to a feature of the present invention, a rotor for an electric motor comprises an inner core fixed to a rotating shaft of the rotor and multiple coil units respectively fixed to the inner core, wherein the coil unit has an outer core, a bobbin and a winding wound on the bobbin, and wherein weight of outer cores as well as winding units (the bobbin and the winding wound thereon) is respectively measured and stratified into several groups, necessary number of the outer cores and winding units are respectively picked out from the same stratified group and then such outer cores and winding units are assembled to the inner core.

Abstract: A bearing 41 of a support portion 4 for rotatably supporting a shaft 11 of a rotating body 10 to be measured with respect to the magnitude of unbalance thereof is formed into a hollow U-shape and has formed therein an injection port 41b for injecting a gas towards the shaft. As the shaft can be supported and floats without making contact with the bearing by virtue of the gas injected from the injection port, the friction can be made small and, hence, a change in rotational speed can be made small. The number and position of the injection ports are determined as required.

Abstract: It is an object of the present invention to provide a method of manufacturing a rotor for an electric motor, in which displacement of the center of gravity is prevented. According to a feature of the present invention, a rotor for an electric motor comprises an inner core fixed to a rotating shaft of the rotor and multiple coil units respectively fixed to the inner core, wherein the coil unit has an outer core, a bobbin and a winding wound on the bobbin, and wherein weight of outer cores as well as winding units (the bobbin and the winding wound thereon) is respectively measured and stratified into several groups, necessary number of the outer cores and winding units are respectively picked out from the same stratified group and then such outer cores and winding units are assembled to the inner core.