Ebara Corporation

Daisuke Konno

Shunichi Aiyoshizawa

Yoshio Sato

Kazuyuki Kasahara

Kazuto Hirokawa

Yumiko Noda

Sachihiko Miwa

Yoichi Kanemitsu

Yuji Shirao

Yasushi Hisabe

Toshihiro Ohtani

Manabu Toshimitsu

Takashi Kataoka

Masahiko Kishi

Toshiya Kanamori

Kimio Komata

Yoshikazu Suganuma

Noriyuki Osada

Hideo Tsuboi

Isami Nitta

Hideo Furukawa

Tetsuo Tanaka

A polygon mirror rotor includes a ceramic ring of a generally hollow cylindrical shape having a cylindrical inner surface serving as a sliding surface of a radial hydrodynamic bearing and a pair of end surfaces each serving as a sliding surface of a thrust hydrodynamic bearing. A plastic ring is fixedly fitted over the ceramic ring, and a polygon mirror made of aluminum is fixedly fitted over the plastic ring by shrinkage fit. The plastic ring has a thermal expansion coefficient greater than that of the ceramic ring as well as greater than that of the aluminum polygon mirror, thereby providing a polygon mirror rotor which does not adversely affect the jitter characteristic of a motor incorporating the rotor.

Polygon mirror rotor and polygon mirror scanner motor having such rotor

A drum motor for a VCR includes radial and thrust hydrodynamic bearings that are composed of a rotor-side bearing member formed by bringing a pair of first and second thrust plates into direct contact with both end surfaces of a radial bearing element and integrating them into one unit, and a stator-side bearing member in the form of a radial sleeve the inner peripheral surface and both end surfaces of which respectively cooperate with the outer peripheral surface of the radial bearing element and the mutually facing surfaces of the first and second thrust plates. A rotor magnet is secured to a rotating shaft. A motor casing is secured to the outer peripheral surface of the radial sleeve. A stator unit is secured to the motor casing. A dynamic pressure generating groove is provided on either each end surface of the radial sleeve or each of the mutually facing surfaces of the first and second thrust plates. The run-out of a rotor-side unit in both the thrust and radial directions is made extremely small and the change in the relative height of the rotor-side unit in the thrust direction due to a change of the position of the motor in which it is used is minimized.

Drum motor for VCR

A bearing device suitable for a spindle motor, which comprises a base, a spindle stood on a central portion of the base, a radial cylindrical member (4) fixed on the spindle, a pair of thrust plates (3) secured to both end surfaces of the radial cylindrical member, and a radial sleeve (6) rotatably supported by the thrust plates (3) and the radial sleeve (6), wherein a radial hydrodynamic bearing is formed by the radial cylindrical member (4) and the radial sleeve (6), thrust hydrodynamic bearings are formed by both end portions of the radial sleeve (6) and the thrust plates (3), a gas is employed as a fluid for generating dynamic pressure in the thrust hydrodynamic bearings, the radial bearing has a minute clearance, a chamfer portion is provided on the outer periphery of each end of the radial cylindrical member (4), and another chamfer portion is provided on the inner periphery of each end of the radial sleeve (6), thereby providing an air gap (13) at each axial end of the radial hydrodynamic bearing, which is surrounded by these chamfer portions and one thrust plate (3), a lubricating liquid is employed as a fluid for generating dynamic pressure in the radial hydrodynamic bearing, small holes (8) for collecting the lubricating liquid are formed in the outer peripheral surface of the radial cylindrical member (4), and lubricating liquid is sealed in the bearing clearance of the radial hydrodynamic bearing by virtue of the presence of the air gaps (13).

Hydrodynamic fluid bearing with liquid-radial bearing and gas-thrust

A spindle motor has a rotor supported by a stator through a thrust bearing and a radial bearing. At least the thrust bearing is a hydrodynamic bearing. The spindle motor is provided with a device for adjusting the thrust laod that is applied to the thrust bearing. The load adjusting device has an electromagnet that is provided on the stator and a permanent magnet that is provided on the rotor in opposing relation to the electromagnet. Either the repelling force or the attraction force, which acts between the electromagnet and the permanent magnet, is controlled by changing the current supplied to the electromagnet.

Spindle motor

A bearing structure suitable for a spindle motor or the like, which enables such a motor to rotate with minimal vibrations. The bearing structure comprises a stator including a support shaft which is disposed on a base, and a rotor which is rotatably disposed around the support shaft. A radial hydrodynamic bearing and a thrust hydrodynamic bearing are disposed between the stator and the rotor. The stator has the support shaft, a thrust plate and a radial cylindrical member which is concentric with the support shaft. The thrust plate is secured to an end surface of the radial cylindrical member. The support shaft extends through the centers of the radial cylindrical member and the thrust plate. The rotor has a radial sleeve. The radial hydrodynamic bearing is formed from the inner peripheral surface of the radial sleeve and the outer peripheral surface of the radial cylindrical member, which face each other and either of which is formed with herringbone-shaped grooves for generating dynamic pressure. The thrust hydrodynamic bearing is formed from an end surface of the radial sleeve and a sliding surface of the thrust plate, which face each other and either of which is formed with spiral grooves for generating dynamic pressure. A rolling bearing may be added in order to minimize the starting torque in the bearing structure.

Bearing structure

A spindle motor which is designed to rotate with minimal vibrations and hence is suitable for a hard disk driver. The spindle motor employs hydrodynamic bearings as radial and thrust bearings. A support shaft is formed in a cylindrical configuration with a center hole, and a rotor has a columnar portion which is inserted into the center hole in the support shaft. A thrust bearing collar is attached to the lower end of the rotor, and a thrust bearing member is secured to a base in opposing relation to the thrust bearing collar. A group of stator coils and a radial bearing member are disposed on either the inner peripheral surface of the center hole in the support shaft or the outer peripheral surface of the support shaft, and a group of rotor magnets and a radial bearing sleeve are disposed on either the outer peripheral surface of the columnar portion or the inner peripheral surface of the rotor in opposing relation to the stator coil group and the radial bearing member.

A spindle motor comprising a stator including a support shaft positioned on a base, a cap-shaped rotor rotatably and concentrically disposed around the support shaft, thrust and radial bearings disposed between the stator and the rotor, a stator coil secured to the stator, and a rotor magnet member secured to the rotor opposing the stator coil. The thrust and radial bearings are hydrodynamic bearings. A movable piece that constitutes a part of the thrust bearing is secured to the lower end of a cylindrical portion of the rotor and extended outwardly or inwardly from the cylindrical portion, or is disposed above the rotor. The stator coil is secured to the outer peripheral portion of the support shaft above or below the radial bearing. The rotor magnet member is securd to the inner peripheral surface or inner top surface of the rotor. Either a radial or axial gap is provided between the stator coil and the rotor magnet member.

Gas dynamic bearing for spindle motor

A sealing means is disclosed which comprises a support member provided with a groove adapted to receive an annular seal therein which mates with the outer spherical surface of a swivel ball of a tank mixer upon installation thereof. The groove is positioned so that it is disposed between the diametrical section of the ball taken substantially parallel to the tank wall and the tank wall and that the internal pressure of the liquid in the tank urges the seal towards the diametrical section of the ball.

Growing community of inventors

Kanagawa, Japan

Daisuke Konno