1.

論文(AKAGI収録)

論文(AKAGI収録)
長屋, 幸助 ; 林, 乃生幸 ; 大関, 健一郎
出版情報: 日本機械学會論文集. C編.  66  pp.1130-1137,  2000-04-25.  日本機械学会
概要: This article presents a new levitation technique, which uses a small superconductor and a set of permanent magnets. In the system, a small superconductor is connected to the bottom of the vertical shaft. The gravity force and axial vibration force are supported by the superconductor. A circular permanent magnet is attched to the top of the shaft, and the other circular permanent magnet lies at the frame. The N-pole of one of the magnets faces to the S-pole of the other magnet, so a drag force acts between the magnets. The drag force is unstable in the axial direction, but the pinning force in the axial direction of the superconductor makes it stable. There is a restoring force in the horizontal direction between two permanent magnets, and in addition, there is a pinning force of the superconductor, so that both ends of the shaft are stable in the horizontal direction. This implies that the levitated shaft is stable without control. In general, controls have to be made in either axial or horizontal direction when the ordinary magnets are used. The levitation technique presented in this paper has advantages, Because, in order to have stable levitation, only one small superconductor is required, and a cooling system is simple. A method for passing through the critical speeds is also presented. In the method, rotating conductor disc is used to have the electromagnetic damping. Both the analysis and experiment are presented. 続きを見る
2.

論文(AKAGI収録)

論文(AKAGI収録)
長屋, 幸助 ; 武田, 定彦 ; 津久井, 洋一 ; 熊井戸, 孝勇
出版情報: 日本機械学會論文集. C編.  52  pp.997-1002,  1986-03-25.  日本機械学会
概要: This paper presents a method for passing critical speeds of a rotating shaft by use of support springs made of memory metals. In this method the vibrations of the shaft due to whirlings are controlled by use of the on (heating) and off (cooling) heat control of the memory metals which support the bearings. In the analysis, the exact solution is obtained on the problem of a multi-span shaft carrying a disc. Numerical calculations have been carried out for some important problems and experimental tests have also been carried out to verify the present control method and the theoretical results. 続きを見る
3.

論文(AKAGI収録)

論文(AKAGI収録)
長屋, 幸助 ; 池田, 真治
出版情報: 日本機械学會論文集. C編.  51  pp.3354-3362,  1985-12-25.  日本機械学会
概要: This paper discusses the bending vibration characteristics of a rotating shaft of a motor, with consideration of the electromagnetic sucking force which acts on a rotor, caused by the narrow electromagnetic field between a stator and the rotor. The dynamic response of the motor under the action of the whirling load of the shaft has been analyzed systematically by considering both the translational and rotary motions of the motor. In the analysis, the transfer matrix method is utilized to obtain the response of the shaft. The equation of longitudinal vibrations of a viscoelastic body is applied to the analysis of the viscoelastic foundation under the assumption of the structural damping. Numerical calculations have been carried out for the critical speeds and the response of both the shafts and the motor. 続きを見る