Magnetic Fluid Patents (Class 384/133)
  • Patent number: 9000643
    Abstract: Provided with a sealed rotational output unit (3) which includes a tubular shaft (12) having an outer circumferential surface sealed with a ferrofluidic seal (13); a rotating output shaft (14) disposed inside the tubular shaft (12); and an O-ring (17, 18) that seals between the tubular shaft (12) and the rotating output shaft (14). When the rotating output shaft (14) is directly coupled to a hollow motor shaft (9), shaking thereof is absorbed by the O-ring (17, 18), causing no excessive stress to be produced on the bearing side of the hollow motor shaft (9) or on a bearing (15, 16) side of the ferrofluidic seal (13). Since the tubular shaft (12) rotates in conjunction with the rotating output shaft (14), the O-ring (17, 18) that seals therebetween does not degrade in sealing capability due to wear by sliding. The sealed rotational output unit can be used with high rotational accuracy by directly coupling to a hollow motor (2) without any joint.
    Type: Grant
    Filed: May 12, 2011
    Date of Patent: April 7, 2015
    Assignee: Harmonic Drive Systems Inc.
    Inventor: Manabu Kino
  • Patent number: 8418671
    Abstract: A system and method are disclosed for reducing the fuel consumption of an engine, particularly during a cold start or an engine warm-up period. A magnetorheological fluid having a low viscosity is used to lubricate the engine. When viscosity is to be increased, a magnetic field is applied to the magnetorheological fluid. The magnetic field can be selectively applied to electromagnets proximate engine bearings.
    Type: Grant
    Filed: October 31, 2012
    Date of Patent: April 16, 2013
    Assignee: Ford Global Technologies, LLC
    Inventors: Jonathan Terence Joseph O'Neill, Ian Grahem Pegg
  • Patent number: 8336516
    Abstract: A system and method are disclosed for reducing the fuel consumption of an engine, particularly during a cold start or an engine warm-up period. A magnetorheological fluid having a low viscosity is used to lubricate the engine. When viscosity is to be increased, a magnetic field is applied to the magnetorheological fluid. The magnetic field can be selectively applied to electromagnets proximate engine bearings.
    Type: Grant
    Filed: February 24, 2010
    Date of Patent: December 25, 2012
    Assignee: Ford Global Technologies, LLC
    Inventors: Jonathan Terence Joseph O'Neill, Ian Grahem Pegg
  • Patent number: 8007176
    Abstract: A magnetic fluid is held by a magnetic field in a stationary state and by a centrifugal force during rotation, leaking and splashing of the magnetic fluid caused by the instability of the pumping of a dynamic pressure bearing are prevented without using a magnetic fluid with a high saturation magnetization value, and the service life of the dynamic pressure bearing is extended. For this purpose, a sleeve 3 having a protruding tubular section is fitted and fixed to the outer periphery of the shaft 1 having a thrust plate 2 formed in an axial vicinity so as to be rotatable relatively to the shaft, an annular cover 4 is formed outwardly from the thrust plate 2 in an axial direction, the radially inward end of the annular cover 4 serves as an opening, at least two clearance sections serve as a reservoir 10 for reserving the magnetic fluid, and a magnetomotive force member 15 is provided for concentrating the magnetic flux lines on the radially outer side of the end portion 13 of the magnetic fluid 12.
    Type: Grant
    Filed: June 24, 2004
    Date of Patent: August 30, 2011
    Assignee: Ferrotec Corporation
    Inventors: Akira Yamamura, Heiichi Unozawa
  • Patent number: 7810999
    Abstract: A metal bearing having a long operating life that is not affected by the operating temperature. The metal bearing includes a bearing surface capable of slidably contacting with a shaft member, including pores in a surface and interior thereof, and being composed of a sintered compact having a metal or alloy as a main component. A dispersion solvent is provided inside the pores, and maghemite particles exist in the dispersion solvent together with at least one of a gas and a liquid that has a boiling point lower than a boiling point of the dispersion solvent.
    Type: Grant
    Filed: April 28, 2006
    Date of Patent: October 12, 2010
    Assignee: Aisin Seiki Kabushiki Kaisha
    Inventor: Hiroshi Kobayashi
  • Publication number: 20080116757
    Abstract: A motor having a magnetic fluid bearing structure, which includes at least one bearing, at least one magnetic element and a magnetic fluid. The bearing is telescoped onto a shaft, and the magnetic element is coupled to the bearing. The magnetic fluid is kept between the bearing and the shaft. According to a magnetic effect between the magnetic fluid and the magnetic element, it is possible to prevent a lubricant of the bearing from leaking, and a hydraulic pressure of the magnetic fluid provides additional axial and radial supports to make the shaft rotate steadily relative to the bearing.
    Type: Application
    Filed: November 14, 2007
    Publication date: May 22, 2008
    Inventors: Sean CHANG, Chii-How CHANG, Chin-Chun LAI, Li-Ming CHEN, Ching-Hsiang YU, Chia-Chi WU
  • Patent number: 7129609
    Abstract: A magneto-fluidic seal includes a shaft; a sleeve surrounding the shaft; a housing made of soft magnetic material surrounding the sleeve; a magnet conducting a magnetic flux to the sleeve; and a magnetic fluid in a gap between the sleeve and the shaft, and/or in a gap between the sleeve and the housing. Optionally, the sleeve includes a channel on a longitudinal side, and wherein the magnet is positioned in the channel. The channel can be substantially circular or polyhedral. The magnet is preferably offset from a bottom of the channel, and oriented radially. Preferably, the magnet includes a plurality of segments, or flat plate-shaped magnets, arranged substantially evenly and circumferentially around the shaft.
    Type: Grant
    Filed: August 30, 2005
    Date of Patent: October 31, 2006
    Assignee: Ferrolabs, Inc.
    Inventors: Yuri O. Mikhalev, Sergei G. Lysenkov
  • Patent number: 7011970
    Abstract: This new automatic bio-manipulation factory system for manipulating a single cell comprises: a bio-MEMS that transports, separates, and extracts a single cell for manipulation from a plurality of cells, controls the rotation-orientation of the extracted cell automatically, and enables the extracted cell to maintain a certain temperature; and a micro manipulation system that obtains vision information and manipulation information about the extracted single cell and the manipulation tool, provides such information to operator, manipulates the extracted single cell by transmitting the rotation-orientation feedback information and the cell manipulation order of the operator to the bio-MEMS, and manipulates the manipulation tool by transmitting the tool manipulation order of the operator to the manipulation tool. The conventional manual and individualized single cell manipulation can be automated and processed collectively by systematically combining the bio-MEMS with the micro manipulation system.
    Type: Grant
    Filed: March 25, 2003
    Date of Patent: March 14, 2006
    Assignee: Korean Institution of Science and Technology
    Inventors: Byung-Kyu Kim, Jung-Yul Park, Deok-Ho Kim, Jong-Oh Park
  • Patent number: 7005768
    Abstract: A securing surface of a housing comprises a deformation region, which deforms radially outward by a predetermined quantity during press fitting of a thrust member, and another region. The deformation region has a tapered shape that gradually reduces in diameter in the downward direction, and is receded radially inward relative to the other region of the securing surface, by an amount equivalent to the amount of outward deformation thereof during press fitting. When the thrust member is press fitted into the inner periphery of a press fitting portion of the housing, the securing surface of the housing becomes substantially straight along entire axial region L thereof.
    Type: Grant
    Filed: November 12, 2003
    Date of Patent: February 28, 2006
    Assignees: Nidec Corporation, NTN Corporation
    Inventors: Takehito Tamaoka, Tetsuya Kurimura, Ryouichi Nakajima
  • Patent number: 6851859
    Abstract: A bearing unit comprises a bearing 60 formed of a sintered metal in which a magnetized magnetic powder is dispersed in its matrix and at least pores exposed on a bearing surface thereof are sealed by impregnation with a resin; a non-magnetic housing 90 accommodating the bearing 60; and a lubricating fluid M made of a magnetic fluid.
    Type: Grant
    Filed: February 6, 2003
    Date of Patent: February 8, 2005
    Assignees: Hitachi Powdered Metals Co., Ltd., Minebea Co., Ltd.
    Inventors: Toshikazu Takehana, Hidekazu Tokushima, Hideo Shikata, Katsutoshi Nii, Jun Hirose
  • Patent number: 6851638
    Abstract: A rotation support structure for a dual-bearing reel includes a reel unit, a spool shaft, and fluid bearings. The spool shaft is disposed on an inner circumferential side of the reel unit and can rotate relative to the reel unit. The fluid bearings have a plurality of grooves for forming a fluid lubricant film between the reel unit and the spool shaft. The rotation support structure is provided for a high-speed rotation operation of a dual-bearing reel, with which a reduction of the rotation performance during high-speed rotation can be successfully suppressed.
    Type: Grant
    Filed: April 18, 2003
    Date of Patent: February 8, 2005
    Assignee: Shimano Inc.
    Inventors: Mitsuyo Maeda, Yasuhiro Hitomi
  • Patent number: 6787954
    Abstract: A downsized spindle motor of excellent abrasion and shock resistance is provided. A shaft is fit into a sleeve. A flange is fixed to an end of the shaft. A radial bearing is formed on faces of the shaft and the sleeve, which faces are opposite and close to each other. A face of the flange closely faces a face of a thrust plate, thereby forming a thrust bearing. Another face of the thrust plate is caulked with a tip of the sleeve. The tip of the sleeve and the thrust plate are fixed to each other by an adhesive. A tapering section is provided at an upper end of the sleeve.
    Type: Grant
    Filed: May 14, 2002
    Date of Patent: September 7, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takao Yoshitsugu, Shoichi Yoshikawa
  • Patent number: 6722657
    Abstract: Disclosed is a labyrinth seal assembly for sealing an annular gap defined between a bore of a housing and an outer surface of a cylindrical shaft, wherein the housing and shaft are relatively movable. The seal assembly includes radially inner and radially outer shield rings. The radially inner shield ring has an inner surface which is adapted and configured for support by the shaft. The radially outer shield ring is partially disposed within the sealing channel of the inner shield ring. The outer shield ring includes a casing member, foam seal elements, and a shield element retainer. The foam seal elements depend radially inward into the sealing channel so as to form a circuitous sealing labyrinth therein. The seal elements are formed preferably from polyurethane. A highly viscous fluid is disposed within the circuitous sealing labyrinth.
    Type: Grant
    Filed: May 31, 2002
    Date of Patent: April 20, 2004
    Assignees: Stemco LLC, The Timken Company
    Inventors: Charles Robin Hood, Donald G. Wells, Mark N. Gold, Richard Borowski
  • Patent number: 6558042
    Abstract: A bearing guided ferrofluid seal and seal carrier system that may be used with a bearing assembly with an outer annular ring surface. A seal carrier of the present invention has a carrier ferrofluid seal surface and a carrier bearing surface that includes a first carrier bearing surface and a second carrier bearing surface. A ferrofluid seal may be attached to the carrier ferrofluid seal surface and fixtured to the second carrier bearing surface. The second carrier bearing surface may be attached to the outer annular ring surface. In one preferred embodiment the first carrier bearing surface may be attached to the upper annular ring surface. In a separate preferred embodiment the ferrofluid seal may be attached to the carrier ferrofluid seal surface so that the seal inner diameter of the ferrofluid seal is fixtured to the second carrier bearing surface in order to minimize runout.
    Type: Grant
    Filed: December 28, 2001
    Date of Patent: May 6, 2003
    Assignee: SAE Magnetics(H. K.) Ltd.
    Inventor: John C. Tompkins
  • Patent number: 6305694
    Abstract: A ferrofluid sealing device retaining a ferrofluid between a shaft and a pair of inner and outer pole pieces rotating in opposite directions, in which grooves are formed on a shaft surface that faces the inner diameter surfaces of pole pieces. In the sealing device, one of the pole pieces may be made thicker than the other and further a projection portion can be formed on the shaft surface facing the inner peripheral faces of the pole pieces. The sealing device can prevent, even when the ferrofluid seal is operated at a higher rotation speed, splashing of ferrofluid over the surroundings, thereby avoiding staining the surroundings as well as prolonging its lifetime.
    Type: Grant
    Filed: November 22, 1999
    Date of Patent: October 23, 2001
    Assignee: Ferrotec Corporation
    Inventors: Noboru Yamazumi, Heiichi Unozawa
  • Patent number: 6119553
    Abstract: A rotation transmitting device 1 introduces rotation into a vacuum side space 200 via a flexible meshing type gear drive 4 from an atmosphere side space 100. A first spacer 15 is disposed between ball bearings 13 and 14 of a rotation output shaft 5 positioned at the vacuum side, and a magnetic circuit is formed passing from the spacer 15 and through the ball bearing 13, a shaft portion 51 of the rotation output shaft 5 and the ball bearing 14. A magnetic fluid is filled as lubricant for lubricating potions of the ball bearings 13 and 14, which is retained on these portions by magnetic force generated by the magnetic circuit, whereby these portions are always lubricated appropriately. The magnetic fluid retained on these portions captures wear particles or other dust generated from the ball bearings 13 and 14, preventing these particles from leaking out to the vacuum side.
    Type: Grant
    Filed: December 2, 1998
    Date of Patent: September 19, 2000
    Assignee: Harmonic Drive Systems, Inc.
    Inventors: Toshimi Yamagishi, Yukio Sawada, Yoshio Yamaguchi
  • Patent number: 6020664
    Abstract: An electric spindle motor has a base assembly (19) and a hollow notatable hub (16) housing a motor. The hub (16) is mounted for rotation about an axis and a stator (12) is mounted on the base assembly (19) inside the hub (16). A liquid filled journal bearing (11, 21) acts between the base assembly (19) and the hub (16) to provide radial support of the hub (16). A gas filled thrust bearing (26, 27, 35) also acts between the hub (16) and base assembly (19) to provide at least axial support of the hub (16).
    Type: Grant
    Filed: May 18, 1999
    Date of Patent: February 1, 2000
    Assignee: Data Storage Institute
    Inventors: Zhejie Liu, Mohammed Abdul Jabbar, Qide Zhang, Teck Seng Low, Shixin Chen, Yuen Ann Mah
  • Patent number: 5973878
    Abstract: A recording disk apparatus comprises a clearance between a shaft and a thrust bearing portion tapered in a circumferential direction, a lubricant communication groove of a bearing covered by the shaft so that a lubricant on a radial bearing portion communicates with the lubricant on the thrust bearing portion through the lubricant communication groove, a lubricant circulating path which extends axially from the thrust bearing portion to the radial bearing portion to prevent the lubricant flowing out of the thrust bearing portion from returning directly to the thrust bearing portion without passing the radial bearing portion, and/or a clearance between a slide bearing and a magnetic fluid seal device substantially filled with a magnetic fluid lubricant.
    Type: Grant
    Filed: August 19, 1997
    Date of Patent: October 26, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Yoshida, Takashi Kono, Kenji Tomida, Tomoaki Inoue, Masaaki Nakano, Hideaki Amano, Kenji Mori
  • Patent number: 5828795
    Abstract: A sealing device for use in a motor. The motor, which maintains a shaft: and a frame that are interconnected by a bearing, includes a magnetic-fluid-seating device and a collecting device. The magnetic-fluid-sealing device seals the bearing with a magnetic fluid to prevent particles and fluids from escaping the bearing, whereas, the collecting device collects any particles and fluids which may escape the magnetic-fluid-sealing device.
    Type: Grant
    Filed: September 25, 1997
    Date of Patent: October 27, 1998
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Toshihiko Miyakoshi, Masato Gomyo, Toshihiro Kobayashi, Masamichi Hayakawa, Hirofusa Shirai, Kenji Hanabusa
  • Patent number: 5810481
    Abstract: Oil retaining bearing members 2a and 2b for supporting a rotative shaft 1 are arranged in a bearing housing 7 with an interval. The bearing housing 7 has a bottom portion, one end being opened and another end being closed. A porous spacer 3 for supplying a lubrication oil is closely inserted between the oil retaining bearings 2a and 2b. An oil thrower 8 is arranged at an upper portion of the bearing housing 7 and a thrust bearing 5 is arranged at a lower portion. The open end of the bearing housing 7 is arranged on the upper portion and the another end of the bearing housing 7 is arranged on the lower portion of the bearing housing 7, and state a lubrication oil 4a is enclosed in the housing to immerse a part of the porous spacer 3 to some degree. The pore diameter of the porous spacer 3 is larger than that of the oil retaining bearings 2a and 2b. By utilizing capillary tube action in by the porous spacer 3, the lubrication oil 4a is supplied to the oil retaining bearing 2a.
    Type: Grant
    Filed: May 6, 1997
    Date of Patent: September 22, 1998
    Assignees: Hitachi, Ltd., Hitachi Powdered Metals Co., Ltd.
    Inventors: Katsutoshi Nii, Makoto Kondoh, Takashi Kono, Yoshihiro Sato, Seiichiro Terashima
  • Patent number: 5793135
    Abstract: To provide a bearing structure of a flat type brushless motor for floppy disk drive in which a stator is arranged in a plane shape and a disk acting as a rotor yoke rotates along the plane shape without the use of conventional ball bearings so that the bearing structure can be high in the rigidity, stable in the motion, and low in the cost. For having a maximum bearing length, the bearing structure comprises a support shaft arranged with its axis extending depthwisely of the motor and having two journal regions provided on both ends thereof and a recessed region thereof between the two journal regions; and a rotor shaft mounted in the center of the disk and having a cylindrical body thereof onto which the journal regions of the support shaft are rotatably fitted. Accordingly, the motor will minimize the frictional loss of the sleeve bearing and increase its operational life. Also, the steadiness (of deflection, inclination, and rigidity) in bearing action will be enhanced.
    Type: Grant
    Filed: May 6, 1997
    Date of Patent: August 11, 1998
    Assignee: Minebea Co., Ltd.
    Inventors: Yuzuru Suzuki, Taketoshi Ohyashiki
  • Patent number: 5789836
    Abstract: A motor having a dynamic pressure bearing device equipped with a rotor having a driving coil or a driving magnet, and a stator having the other of the driving coil or the driving magnet, the dynamic pressure bearing device comprising a shaft fixed to the rotor or the stator and having a dynamic pressure surface on its outer surface, a bearing body fixed to the other of the rotor or stator and having a dynamic pressure surface on its inner surface which is positioned to circumferentially confront the outer surface of the shaft body, a dynamic pressure generating groove formed on at least one side of both the dynamic pressure surfaces, and a lubricating fluid in which magnetic particles are dispersed in a base oil solvent containing an amine anti-gelling agent interposed between both of the dynamic pressure surfaces.
    Type: Grant
    Filed: March 25, 1996
    Date of Patent: August 4, 1998
    Assignee: Sankyo Seiko Mfg. Co., Ltd.
    Inventor: Masamichi Hayakawa
  • Patent number: 5778948
    Abstract: A method for inserting fluid in a bearing device containing a fixed member and a rotating member. The fixed member and the rotating member of the bearing device are assembled in a high pressure environment and subsequently placed in a low pressure environment. While in the low pressure environment, bearing fluid is placed in a space between the fixed member and the rotating member. The fixed member and rotating member along with the bearing fluid are then placed in the high pressure environment to fully disperse the bearing fluid in the space between the fixed member and the rotating member.
    Type: Grant
    Filed: June 28, 1995
    Date of Patent: July 14, 1998
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Masato Gomyo, Kazuaki Oguchi
  • Patent number: 5676472
    Abstract: A rotary seal is located in a gap between an inner surface and an outer surface. A radial bearing allows the inner and outer surfaces to rotate relative to each other. A radial barrier includes a plurality of annular outward-pointing flanges attached to the inner surface interleaved with a plurality of annular inward-pointing flanges attached to the outer surface. The flanges may be angled and have an upturned lip located at an inner edge of each flange. The radial seal may include a magnet. A robotic arm has a first housing with a top surface and an aperture therein. A shaft extends up through the aperture, and there is a gap between the shaft and an inner edge of the aperture. A splash guard may extend over said gap, and an indentation in said top surface may at least partially surround the gap.
    Type: Grant
    Filed: July 10, 1995
    Date of Patent: October 14, 1997
    Assignee: Smart Machines
    Inventors: Todd Solomon, Donald J. Thomas
  • Patent number: 5667309
    Abstract: A bearing seal system having a bag structure in a first embodiment wherein (1) oil is filled in a tapering bag space section positioned from the bag section to an exit section; (2) the space in the tapering space section is kept to 0.8 mm or less the slope angle of the outer end of the tapering space section is kept to 45.degree. or less. In this way, oil is kept from air and a stable no-leak status is made possible; (3) the capacity of the tapering space section is made larger than that of a bag section or a radial bearing section in order to retain oil in the bearing section at all times and to prevent oil from leaking as a result of variations in the quantity of oil injected or in the capacity; and (4) the space ratio of the inner end and the outer end of the tapering space section is made larger to prevent oil from moving to the bearing section even when air migrates into the oil surface.
    Type: Grant
    Filed: November 14, 1995
    Date of Patent: September 16, 1997
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventor: Tamotsu Nose
  • Patent number: 5653541
    Abstract: A magnetic disk driving device includes a frame which supports a shaft, a hub adapted to hold a disk, and upper and lower bearings which are fitted in a bearing holding hole and rotatably support the hub. The frame includes a cylindrical protrusion which is confronted through a small gap d with the outer cylindrical surface of the outer race of the lower bearing. The small gap d forms a labyrinth in the space through which the inside of the lower bearing is communicated with the outside. The inner cylindrical surface of an annular protrusion formed on the bottom of the hub, and the inner cylindrical surface of the cylindrical protrusion are substantially equal in diameter.
    Type: Grant
    Filed: August 15, 1995
    Date of Patent: August 5, 1997
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Yutaka Ishizuka, Shinji Kinoshita
  • Patent number: 5645355
    Abstract: A bearing unit in which two oil sintered slide bearings are fitted in a bearing space of non-magnetic bearing housings to be spaced away from each other and a magnetic fluid is interposed between a rotary shaft and the oil sintered slide bearings to rotatably support the rotary shaft. The rotary shaft is made from a material having permeability, and a ring-shaped permanent magnet is fixedly provided between the two oil sintered slide bearings to be spaced therefrom. The magnetic fluid is held between the two oil sintered slide bearings to be circulated.
    Type: Grant
    Filed: June 3, 1996
    Date of Patent: July 8, 1997
    Assignees: Hitachi, Ltd., Hitachi Powdered Metals Co., Ltd.
    Inventors: Hidekazu Tokushima, Motohiro Miyasaka, Michihiro Aizawa, Hideo Shikata, Katsutoshi Nii
  • Patent number: 5628569
    Abstract: A fluid bearing unit includes a shaft; a bearing; bearing fluid arranged between a shaft and a bearing which are rotatably engaged with each other so that they can be relatively rotated so as to generate dynamic pressure in the bearing fluid, wherein at least one of the bearing and the member for fixing the bearing unit is made of iron alloy having the volumetric magnetostriction of which acts to cancel the thermal expansion so as to become the coefficient of linear expansion thereof lower than that of the shaft.
    Type: Grant
    Filed: October 18, 1994
    Date of Patent: May 13, 1997
    Assignee: Kabushiki Kaisha Sankyo Seiki Seisakusho
    Inventors: Masamichi Hayakawa, Masato Gomyo, Toshihiko Miyakoshi, Arihiro Yonezawa
  • Patent number: 5417507
    Abstract: There is disclosed a polygon mirror motor in which an annular projection is formed on an upper surface of a rotor support member supporting a polygon mirror, and the annular projection supports a part of a lower surface of the polygon mirror. Radial bearings supporting a shaft of the motor have a plurality of oil grooves extending over about a half of the dimension of the radial bearing in a thrust direction. A magnetic fluid is filled in a space defined by the shaft, a support tube of a bearing support member and the radial bearings.
    Type: Grant
    Filed: February 4, 1993
    Date of Patent: May 23, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Satosi Uno, Jun Matsubayashi, Katsutoshi Nii, Kazuhiko Kawaike
  • Patent number: 5372432
    Abstract: A dynamic pressure bearing with a magnetic fluid sealed therein is reduced in size without degrading the bearing performance and includes a sleeve 5 having an insertion hole 6 axially formed therein fixed in a housing 1, and a pair of pole pieces 9a, 9b disposed with clearances defined between the opposed surfaces of the sleeve 5 and the housing 1. A shaft 7 is inserted in and fixed to the pole pieces 9a, 9b, and is disposed in the insertion hole 6 with a clearance defined therebetween, and a magnetic fluid 15 is sealed in these clearances, thus forming a dynamic pressure bearing assembly. The sleeve 5 is made of nonmagnetic material while the housing 1, shaft 7 and pole pieces 9a, 9b are made of magnetic material. A permanent magnet 2 is interposed therebetween to form magnetic fields in the clearances between the housing 1 and the pole pieces 9a, 9b, thus sealing the magnetic fluid 15 therein.
    Type: Grant
    Filed: July 16, 1993
    Date of Patent: December 13, 1994
    Assignee: Nippon Ferrofluidics Corporation
    Inventor: Ryuhei Ishikawa
  • Patent number: 5323076
    Abstract: A disk spindle motor having a permanent magnet central shaft. A pair of annular, non-magnetic combination thrust and journal bearings having truncated-conical outer surfaces are spaced apart on the shaft. The bearings coact with complementary surfaces of the hub of a motor rotor. Shaft end caps connect the shaft to base means and have radially extending shoulders which define annular gaps with the rotor and function as ferrofluidic seals.
    Type: Grant
    Filed: January 22, 1993
    Date of Patent: June 21, 1994
    Inventor: Chester S. Hajec
  • Patent number: 5256952
    Abstract: A control method and apparatus for suppressing the vibration components of a magnetic bearing. According to this invention, a vibration wave is sampled at pulses synchronized with the rotation of a rotor, the vibration waveform sampled values at each revolution are averaged, and only the frequency components synchronized with the rotation frequency of the rotor are extracted from the vibration waveform. In addition, the extracted components are subjected to Fourier transform, processed in a frequency region and subjected to Fourier reverse transform. The sequence of these signal processes produces a signal, and the vibration components are suppressed by this signal.
    Type: Grant
    Filed: May 29, 1992
    Date of Patent: October 26, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Mitsuho Yoneyama, Osami Matsushita, Naohiko Takahashi, Yasuo Fukushima
  • Patent number: 5238254
    Abstract: A ferrofluid seal apparatus comprises magnetic fluid holding means for storing a magnetic fluid with one of an inner and an outer elements which are relatively rotated. The magnetic fluid holding means has a storage section for storing a part of the magnetic fluid which flows out of said magnetic fluid holding means.
    Type: Grant
    Filed: February 20, 1992
    Date of Patent: August 24, 1993
    Assignee: Koyo Seiko Co., Ltd.
    Inventors: Hirokazu Takii, Tetsuo Oda, Shinji Abe, Kazuya Suzuki, Hirotsugu Kusano
  • Patent number: 5165701
    Abstract: A magnetic fluid seal apparatus adapted to prevent a magnetic fluid from being displaced along a shaft or housing during linear motion of the shaft. In the apparatus of the bore mounted type, a pole piece is hermetically fixed within a bore of the housing, while an associated inner ring is fitted over the shaft so as to form an annular magnetic gap in which the magnetic fluid is magnetically retained. The inner ring has an axial length smaller than that of the pole piece. Thus, a portion of the magnetic fluid is retained along the outer face of the inner ring, while the remainder of the fluid is retained along the inner face of the pole piece to form a film of magnetic fluid. The pole piece has an axial length equal to or greater than the travel of linear motion of the shaft so that the portion of magnetic fluid retained along the inner ring is in continuous, integrated fluid-to-fluid engagement with the film of magnetic fluid throughout the travel of the shaft.
    Type: Grant
    Filed: February 12, 1992
    Date of Patent: November 24, 1992
    Assignee: Nok Corporation
    Inventor: Akihiko Koba
  • Patent number: 5161900
    Abstract: A bearing using magnetic fluid for lubrication is provided with a magnetic seal circuit to retain the magnetic fluid in the baring. The magnetic seal circuit comprises two annular ring magnets surrounding a shaft and placed on opposite sides of the bearing. The two ring magnets are magnetically joined by a shunt. The shunt controls stray flux and permits the disposition of the magnet at a small distance from the shaft, thus concentrating the flux in the magnetic seal gap.
    Type: Grant
    Filed: April 10, 1992
    Date of Patent: November 10, 1992
    Assignee: International Business Machines, Corp.
    Inventors: Zine-Eddine Bougathou, Peter M. Herman
  • Patent number: 5155640
    Abstract: The present invention is a disk spindle motor cap. By affixing the cap to the cylindrical shaft of a disk drive, the amount of magnetic ferrofluid escaping from the well between the hub and the cylindrical shaft of the disk spindle assembly is reduced.
    Type: Grant
    Filed: May 3, 1990
    Date of Patent: October 13, 1992
    Assignee: Microscience International Corp.
    Inventor: Yu-Chuan Lee
  • Patent number: 5134331
    Abstract: A spindle motor includes a bracket, a shaft member fixed to the bracket, a hub member rotatably mounted on the shaft member with a bearing member therebetween, a rotor magnet mounted on the hub member, a stator disposed in opposed relation to the rotor magnet, and a magnetic fluid sealing means disposed on an outer side of the bearing means. The shaft member or bracket has a magnetized portion for suppressing a magnetic flux leaking from a magnetic fluid retaining means of the magnetic fluid sealing means.
    Type: Grant
    Filed: May 28, 1991
    Date of Patent: July 28, 1992
    Assignee: Nippon Densan Corporation
    Inventors: Itsuo Miyaji, Takeshi Uda, Hiroyuki Yonei
  • Patent number: 5110141
    Abstract: Apparatus for restricting magnetic oil to a desired location within a FFFB comprising selectably locatable stopper apparatus having a first location near the FFFB for enabling a vacuum to be produced and for restricting the magnetic oil within the FFFB during filling of the FFFB with the magnetic oil and a second location away from the FFFB when filling is not occurring and apparatus for moving the selectably locatable stopper apparatus between the first location and the second location.
    Type: Grant
    Filed: July 1, 1991
    Date of Patent: May 5, 1992
    Assignee: MSB Technologies Ltd.
    Inventor: Ami Dayan
  • Patent number: 5108198
    Abstract: A sliding bearing an an end ring are mounted on a housing. A magnetic fluid sealing member comprises a permanent magnet and a magnetic fluid. A space is formed between the magnetic fluid sealing member and a lubricating fluid. A shaft has projection member or the end ring forms a spiral groove on an inner peripheral portion. The projection member of the shaft or the spiral groove of the end ring is disposed in an opposite position of the magnetic fluid sealing member. A magnetic fluid flow is disturbed by the projection member of the shaft or the spiral groove of the end ring according to a rotation of the shaft, then a magnetic fluid film is destructed instantaneously and the pressure at the space lowers. Air in the space is discharged from the housing. The scatter degree of the magnetic fluid is made slightly.
    Type: Grant
    Filed: July 17, 1990
    Date of Patent: April 28, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Katsutoshi Nii, Kazuhiko Kawaike, Jun Matsubayashi, Satosi Uno
  • Patent number: 5059039
    Abstract: A bearing bushing incorporating a sleeve (1) of magnetizable material forming the sliding surface of the bearing, a shaft (2) mounted in said sleeve (1) and a lubricant in the form of a magnetic fluid (3) between the sliding surface of the sleeve (1) and the shaft (2), whereby the sleeve (1) is magnetized in axial direction. For causing a hydrodynamic lubrication and an increased cooling effect the sleeve (1) on the inner side has axial channels (7) and axial recesses (9) on the outer side thus that the magnetic fluid (3) by the axial magnetic field around the sleeve (1), can be given a circulating motion along the inner and outer side of the sleeve.
    Type: Grant
    Filed: June 19, 1990
    Date of Patent: October 22, 1991
    Assignee: SKF Nova AB
    Inventor: Rune Adolfsson
  • Patent number: 5054939
    Abstract: A sliding bearing which is mounted on a shaft (2) and is composed by a magnetized material, whereby between the sliding bearing (1) and a surrounding bearing housing (5) is provided a magnetic fluid as lubricating and sealing agent. The sliding bearing (1) has sliding shoes (3) adapted at rotation of the shaft (2) to cause a compression of the fluid volume and to urge fluid to pass out under the sliding shoes at the same time as the hydrostatic pressure increases in the spaces (4) between the sliding shoes (3).
    Type: Grant
    Filed: June 4, 1990
    Date of Patent: October 8, 1991
    Assignee: SKF Nova AB
    Inventor: Rune Adolfsson
  • Patent number: 5052823
    Abstract: A bearing bushing incorporating a sleeve (1) of magnetizable material forming the sliding surface of the bearing, a shaft (2) mounted in said sleeve (1) and a lubricant in the form of a magnetic fluid (3) between the sliding surface of the sleeve (1) and the shaft (2), whereby the sleeve (1) is magnetized in an axial direction. For causing a hydrodynamic lubrication and an increased cooling effect the sleeve (1) has a number of radial holes (4) through which the magnetic fluid (3) may pass to the other side of the sleeve (1), and which, by the axial magnetic field about the sleeve (1), is given a circulating motion along the inner and outer side of the sleeve.
    Type: Grant
    Filed: June 19, 1990
    Date of Patent: October 1, 1991
    Assignee: SKF Nova AB
    Inventors: Rune Adolfsson, Goran Lindsten
  • Patent number: 5036235
    Abstract: A brushless DC motor having a hydrodynamic bearing system includes a stator core having windings arranged thereabout, the stator core rotating about a first center line. The motor further includes a rotor having permanent magnets positioned about an inner diameter thereof, said rotor being rotatable about a second center line. The first center line of the stator core is eccentric to and parallel to the second center line of the rotor such that the magnets exert forces on the stator core which eliminate whirl instability in the rotor.
    Type: Grant
    Filed: July 25, 1990
    Date of Patent: July 30, 1991
    Assignee: Xerox Corporation
    Inventor: Robert J. Kleckner
  • Patent number: 5032751
    Abstract: A magnetic fluid bearing may include a sleeve provided with a through bore, a shaft inserted into the bore, electromagnets engaged with the bore of the sleeve with a gap provided between the shaft and the electromagnets, a magnetic fluid introduced into the gap between the electromagnets and the shaft, and a controller for modifying the magnetic force of the electromagnets in accordance with changes in a load condition of the bearing. One or more electromagnets for radial loads may be engaged with the sides of the bore and an electromagnet for thrust loads may be engaged with a bottom of the bore. The controller has a sensor to detect changes in an inductance or capacitance that are indicative of the position of the shaft. The controller translates the changes into signals and transmits the signals to a power amplifier to modify the position of the shaft by changing the rate of electric current running through the electromagnets.
    Type: Grant
    Filed: June 20, 1990
    Date of Patent: July 16, 1991
    Assignee: Nippon Thompson Co., Ltd.
    Inventor: Kunihiko Morita
  • Patent number: 5011165
    Abstract: A seal includes a magnetic circuit having a permanent magnet providing excitation. A rotatable shaft has a straight cylindrical outer surface and is supported in a ball bearing system. A magnetically conductive bearing ring is mounted on the shaft immediately adjacent one end of the bearing system. The bearing ring has two radial portions of different thicknesses, the outer portion being thinner than the inner portion adjacent the shaft. A permanent magnet ring is located adjacent the bearing ring on the side opposite the bearing system. A labyrinth gap is defined between the bearing system and the permanent magnet ring on both sides of the bearing ring radially extending therebetween, and a ring pole is located axially adjacent the permanent magnet ring on the opposite side of the bearing system. An active pole gap is defined between the inner diameter of the ring pole and the shaft and is filled with a magnetically conductive fluid, the gap being essentially in series with the labyrinth gap.
    Type: Grant
    Filed: May 1, 1989
    Date of Patent: April 30, 1991
    Assignee: Papst-Motoren GmbH & Co. KG
    Inventor: Heinrich Cap
  • Patent number: 5005639
    Abstract: A long life, very low friction pump for use in a heat pipe pump or the like is disclosed. A first pump uses magnetically confined ferrofluid rings as both sealer and lubricant for a sliding pump piston in a two sided piston pump that minimizes the seal pressures on both sides of the ferrofluid seals. A second pump uses a magnetically confined ferrofluid slug as a self-sealing and self-repairing pump piston.
    Type: Grant
    Filed: April 2, 1990
    Date of Patent: April 9, 1991
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventor: John E. Leland
  • Patent number: 4995622
    Abstract: A magnetic fluid seal device, with two or more pole pieces disposed around a magnetic rotating element on both sides of a permanent magnet, each pole piece being formed by alternately joining and first and second magnetic disks differing in inside diameter is related. Tiny gaps are formed between the inner circumference of the magnetic disks having the smaller inside diameter in each pole piece and the outer circumference of the magnetic rotating element, and a magnetic fluid is magnetically captured in these tiny gaps. The magnetic flux density in these gaps is set larger than the saturated magnetization of the magnetic fluid captured in these gaps and the thickness of the first magnetic disks is set somewhare between 0.02 and 0.0 mm.
    Type: Grant
    Filed: February 7, 1989
    Date of Patent: February 26, 1991
    Assignee: Nippon Pillar Packing Co., Ltd.
    Inventor: Toshihiko Fuse
  • Patent number: 4967831
    Abstract: A long life, very low friction pump for use in a heat pipe pump or the like s disclosed. A first pump uses magnetically confined ferrofluid rings are both sealer and lubricant for a sliding pump piston in a two sided piston pump that minimizes the seal pressures on both sides of the ferrofluid seals. A second pump uses a magnetically confined ferrofluid slug as a self-sealing and self-repairing pump piston.
    Type: Grant
    Filed: March 24, 1988
    Date of Patent: November 6, 1990
    Assignee: The United States as represented by the Secretary of the Air Force
    Inventor: John E. Leland
  • Patent number: RE35718
    Abstract: A bearing apparatus comprises a housing formed of a non-magnetizable material and having a bottom portion, a fluid lubricating type radial bearing device provided coaxial with the housing and having a magnetic fluid sealing section and a radial bearing section, a thrust bearing device provided at the bottom portion of the housing, and a rotating shaft of a permeable material rotatable supported by the radial bearing device and thr thrust bearing device to extend through the radial bearing device. The magnetic fluid sealing section is disposed on the opening side of the housing with a predetermined spacing away from the radial bearing section whereby a space is provided between the magnetic fluid sealing section and a liquid surface of fluid lubricant filled in the radial bearing section.
    Type: Grant
    Filed: September 14, 1995
    Date of Patent: January 27, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Katsutoshi Nii, Kazuhiko Kawaike, Hiroo Hiroyama, Satoshi Uno
  • Patent number: RE36202
    Abstract: A disk spindle motor having a permanent magnet central shaft. A pair of annular, non-magnetic combination thrust and journal bearings having truncated-conical outer surfaces are spaced apart on the shaft. The bearing coact with complementary surfaces of the hub of a motor rotor. Shaft end caps connect the shaft to base means and have radially extending shoulders which define annular gaps with the rotor and function as ferrofluidic seals.
    Type: Grant
    Filed: June 12, 1996
    Date of Patent: April 27, 1999
    Inventor: Chester S. Hajec