Abstract: With a view to reduce vibrations generated by a motor and improve resistance to heat, reliability and vibration isolation properties without increasing the cost or the number of manufacturing steps in a rotor for a permanent-magnet motor, a rotor core is formed of an outer peripheral portion by which the permanent magnet is fixed, and a central portion by which a shaft is fixed, a clearance is provided between the outer peripheral portion and the central portion, and the outer peripheral portion is connected to the central portion by means of a plurality of fastening members. Thus, a rotor having excellent vibration isolation properties can be obtained. Since the rotor core is formed of laminated iron plates on which the outer peripheral portion, the central portion and the fastening members are all formed as one piece, resistance to heat, reliability and the vibration isolation properties can be enhanced without increasing the cost or the number of manufacturing steps.

Abstract: A hermetic motor compressor comprises a casing which includes a dome-like upper casing and a dome-like lower casing. Each of the upper and lower casings has an engagement portion for telescopically engaging with each other. The stiffness of the upper casing is increased by making at least three corner portions close to the engagement portion. Crescent-shaped portions, curved surfaces, an apex portion and crest lines are also provided for the upper casing. This specific structure of the upper casing may be made also for the lower casing, and when both of the upper and lower casings have such construction, the corner portions of the upper casing and the corner portions of the lower casing are arranged alternatively so that the vibrating modes of respective casings offset each other. The shape of the entire casing may be spherical or ellipsoidal.