JPS643318A - Rotary device - Google Patents

Abstract

PURPOSE:To prevent vibration caused by resonance by coupling the small cylinder section of a rotor with the large cylinder section of a housing from the open end side thereof so as to be dynamic pressure bearing, arranging a motor in a hermetic space between both of the cylinders, and further forming a small hole communicating to open air. CONSTITUTION:A housing 15 including a large cylinder section 3 and a center projection section 11 is opened at one end side, and the outer diameter of the small cylinder section 2 of a rotor 20 is somewhat smaller than the inner diameter of the large cylinder section 3 with its one end side opened so as to couple these ends with each other. There is a small gap between the bearing surface 13 of the inner circumferential surface of the large cylinder section 3 and the outer circumferential surface of the small cylinder section 2, thereby forming grooves 12 acting as the dynamic pressure bearing. A space 10 is hermetic, including a motor 22 inside for the rotor 20, and the hermetic space 10 is communicated to open air through the small hole 9 of the rotor 20. And thrust magnets 7 and 8 attract each other so as to allow the rotor 20 to be floated from the housing 15. In this case, when disturbance is caused from outside, the rotor 20 starts vibrating to the thrust direction so as to let air come in and out through the small hole while acting as resistance for restraining the rotor from being vibrated by the damping action thereof.