Compound bearing apparatus, and spindle motor and swing arm for hard disk drive means including such bearing apparatus

Abstract

The object of the present invention is to provide a compound bearing apparatus having arrangements for preventing the lubricant present around the rotating bodies from leaking out to the outside as well as the interior space between two rows of rotating bodies of the bearing apparatus. This is effected for the purpose of providing the compound bearing apparatus and a spindle motor and a swing arm assembly for a hard disk drive device including such bearing apparatus in which the sufficient amount of lubricant can be retained around the rotating bodies to obtain long life feature and having substantially no noise or vibration due to the loss of lubricant. The compound bearing apparatus in accordance with the present invention includes a stepped shaft 1 having enlarged diameter shaft portion 1 a and reduced diameter shaft portion 1 b , a sleeve outer race 2 surrounding the stepped shaft, two rows of rotating bodies 3, 4 interposed therebetween, outer sealing plates 10, 11 provided on the outer side of each rotating bodies respectively, and inner sealing plates 13, 14 provided on the inner side of each rotating bodies respectively.

What is claimed is:  
     
         1 . (based on Original  claim 2)  A compound bearing apparatus including a stepped shaft having an enlarged diameter shaft portion and reduced diameter shaft portion, a sleeve outer race surrounding the stepped shaft, and two rows of rotating bodies interposed therebetween, wherein: 
 the rotating bodies of the first row are disposed between an outer peripheral rolling recess formed directly on an outer peripheral surface of the enlarged diameter shaft portion and a first inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 the rotating bodies of the second row are disposed between an outer peripheral rolling recess formed on an outer periphery of an inner race fitted over the reduced diameter shaft portion of said stepped shaft and a second inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 an outer peripheral labyrinth recess formed on the outer peripheral surface of the enlarged diameter shaft portion at the longitudinal inner side of the rotating bodies of the first row,  
 a space defined between a shoulder, formed at a point of transition from the enlarged diameter shaft portion to the reduced diameter shaft portion, and an inner end of the inner race,  
 at the longitudinal outer side of the rotating bodies of the first row, a first outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is slightly larger than the enlarged diameter shaft portion to prevent the first outer sealing plate from contact with the stepped shaft and to provide a labyrinth seal function,  
 at the longitudinal outer side of the rotating bodies of the second row, a second outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the first row, a first inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the enlarged diameter shaft portion and larger than the outer diameter of the labyrinth recess to prevent the first inner sealing plate from contact with the stepped shaft to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the second row, a second inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner ring and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second inner sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function.  
 
     
     
         2 . (Based on Original  claim 12)  The compound bearing apparatus recited in  claim 1 , wherein said outer peripheral labyrinth recess, said space defined between said shoulder and said inner end of the inner race, said first inner sealing plate and said second inner sealing plate cooperate to reduce dispersion of lubricant from said rolling bodies into a space between said two rows of rotating bodies.  
     
     
         3 . (Based on Original  claim 5)  A spindle motor including a rotating member rotor hub journalled on a base by means of a compound bearing apparatus, said compound bearing apparatus comprising: 
 a stepped shaft having an enlarged diameter shaft portion and reduced diameter shaft portion, a sleeve outer race surrounding the stepped shaft, and two rows of rotating bodies interposed therebetween, wherein: 
 the rotating bodies of the first row are disposed between an outer peripheral rolling recess formed directly on an outer peripheral surface of the enlarged diameter shaft portion and a first inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 the rotating bodies of the second row are disposed between an outer peripheral rolling recess formed on an outer periphery of an inner race fitted over the reduced diameter shaft portion of said stepped shaft and a second inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 an outer peripheral labyrinth recess formed on the outer peripheral surface of the enlarged diameter shaft portion at the longitudinal inner side of the rotating bodies of the first row,  
 a space defined between a shoulder, formed at a point of transition from the enlarged diameter shaft portion to the reduced diameter shaft portion, and an inner end of the inner race,  
 at the longitudinal outer side of the rotating bodies of the first row, a first outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is slightly larger than the enlarged diameter shaft portion to prevent the first outer sealing plate from contact with the stepped shaft and to provide a labyrinth seal function,  
 at the longitudinal outer side of the rotating bodies of the second row, a second outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the first row, a first inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the enlarged diameter shaft portion and larger than the outer diameter of the labyrinth recess to prevent the first inner sealing plate from contact with the stepped shaft to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the second row, a second inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner ring and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second inner sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function.  
 
 
     
     
         4 . (Based on Original  claim 11)  The spindle motor recited in  claim 3 , wherein said compound bearing apparatus is configured so that said outer peripheral labyrinth recess, said space defined between said shoulder and said inner end of the inner race, said first inner sealing plate and said second inner sealing plate cooperate to reduce dispersion of lubricant from said rolling bodies into a space between said two rows of rotating bodies.  
     
     
         5 . (Based on Original  claim 8)  A swing arm assembly journalled rotatably on a base of a bard disk drive device through a compound bearing apparatus provided within a base cylindrical portion of a swing arm, said compound bearing apparatus comprising: 
 a stepped shaft having enlarged diameter shaft portion and reduced diameter shaft portion, a sleeve outer race surrounding the stepped shaft, and two rows of rotating bodies interposed therebetween, wherein: 
 the rotating bodies of the first row are disposed between an outer peripheral rolling recess formed directly on an outer peripheral surface of the enlarged diameter shaft portion and a first inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 the rotating bodies of the second row are disposed between an outer peripheral rolling recess formed on an outer periphery of an inner race fitted over the reduced diameter shaft portion of said stepped shaft and a second inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 an outer peripheral labyrinth recess formed on the outer peripheral surface of the enlarged diameter shaft portion at the longitudinal inner side of the rotating bodies of the first row,  
 a space defined between a shoulder, formed at a point of transition from the enlarged diameter shaft portion to the reduced diameter shaft portion, and an inner end of the inner race,  
 at the longitudinal outer side of the rotating bodies of the first row, a first outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is slightly larger than the enlarged diameter shaft portion to prevent the first outer sealing plate from contact with the stepped shaft and to provide a labyrinth seal function,  
 at the longitudinal outer side of the rotating bodies of the second row, a second outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the first row, a first inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the enlarged diameter shaft portion and larger than the outer diameter of the labyrinth recess to prevent the first inner sealing plate from contact with the stepped shaft to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the second row, a second inner sealing plate of ring shape having a central aperture is fixedly fitted at: its outer periphery into an inner peripheral groove formed on the inner peripheral surface of the sleeve outer race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner ring and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second inner sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function.  
 
 
     
     
         6 . (Based on Original  claim 10)  The swing arm assembly recited in  claim 5 , wherein said compound bearing apparatus is configured so that said outer peripheral labyrinth recess, said space defined between said shoulder and said inner end of the inner race, said first inner sealing plate and said second inner sealing plate cooperate to reduce dispersion of lubricant from said rolling bodies into a space between said two rows of rotating bodies.  
     
     
         7 . (Based on Original  claim 3)  A compound bearing apparatus including a stepped shaft having enlarged diameter shaft portion and reduced diameter shaft portion, a sleeve outer race surrounding the stepped shaft, and two rows of rotating bodies interposed therebetween, wherein: 
 the rotating bodies of the first row are disposed between an outer peripheral rolling recess formed directly on an outer peripheral surface of the enlarged diameter shaft portion and a first inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 the rotating bodies of the second row are disposed between an outer peripheral rolling recess formed on an outer periphery of an inner race fitted over the reduced diameter shaft portion of said stepped shaft and a second inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 a space defined between a shoulder, formed at a point of transition from the enlarged diameter shaft portion to the reduced diameter shaft portion, and an inner end of the inner race,  
 at the longitudinal outer and inner side of the rotating bodies of the first row, a pair of first outer and inner sealing plates of ring shape having a central aperture respectively are fitted at their inner peripheries into a pair of peripheral grooves formed on each side of the peripheral rolling recess formed on the outer peripheral surface of the enlarged diameter shaft portion so as to be faced opposite to a pair of outer and inner peripheral grooves formed on each side of the first inner peripheral rolling recess of the sleeve outer race respectively,  
 the outer diameter of the central aperture is substantially equal to or larger than the inner diameter of the sleeve outer race and smaller than the outer diameter of the inner peripheral grooves respectively to prevent the first inner and second sealing plates from contact with the sleeve outer race to provide a labyrinth seal function,  
 at the longitudinal outer side of the rotating bodies of the second row, a second outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into a peripheral groove formed on the outer side of the second inner peripheral rolling recess formed on the inner peripheral surface of the sleeve outer race so as to be faced opposite to an outer side of the inner race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second outer sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the second row, a second inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into a peripheral groove formed on inner side of the second inner peripheral rolling recess formed on the inner peripheral surface of the sleeve outer race so as to be faced opposite to the space between the stepped shaft and the inner race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second inner sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function.  
 
     
     
         8 . (New claim) The compound bearing apparatus recited in  claim 7 , wherein said outer peripheral labyrinth recess, said space defined between said shoulder and said inner end of the inner race, said first inner sealing plate and said second inner sealing plate cooperate to reduce dispersion of lubricant from said rolling bodies into a space between said two rows of rotating bodies.  
     
     
         9 . (Based on Original  claim 6)  A spindle motor including a rotating member rotor hub journalled on a base by means of a compound bearing apparatus, said compound bearing apparatus comprising: 
 a stepped shaft having enlarged diameter shaft portion and reduced diameter shaft portion, a sleeve outer race surrounding the stepped shaft, and two rows of rotating bodies interposed therebetween, wherein: 
 the rotating bodies of the first row are disposed between an outer peripheral rolling recess formed directly on an outer peripheral surface of the enlarged diameter shaft portion and a first inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 the rotating bodies of the second row are disposed between an outer peripheral rolling recess formed on an outer periphery of an inner race fitted over the reduced diameter shaft portion of said stepped shaft and a second inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 a space defined between a shoulder, formed at a point of transition from the enlarged diameter shaft portion to the reduced diameter shaft portion, and an inner end of the inner race,  
 at the longitudinal outer and inner side of the rotating bodies of the first row, a pair of first outer and inner sealing plates of ring shape having a central aperture respectively are fitted at their inner peripheries into a pair of peripheral grooves formed on each side of the peripheral rolling recess formed on the outer peripheral surface of the enlarged diameter shaft portion so as to be faced opposite to a pair of outer and inner peripheral grooves formed on each side of the first inner peripheral rolling recess of the sleeve outer race respectively,  
 the outer diameter of the central aperture is substantially equal to or larger than the inner diameter of the sleeve outer race and smaller than the outer diameter of the inner peripheral grooves respectively to prevent the first inner and second sealing plates from contact with the sleeve outer race to provide a labyrinth seal function,  
 at the longitudinal outer side of the rotating bodies of the second row, a second outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into a peripheral groove formed on the outer side of the second inner peripheral rolling recess formed on the inner peripheral surface of the sleeve outer race so as to be faced opposite to an outer side of the inner race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second outer sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the second row, a second inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into a peripheral groove formed on inner side of the second inner peripheral rolling recess formed on the inner peripheral surface of the sleeve outer race so as to be faced opposite to the space between the stepped shaft and the inner race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second inner sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function.  
 
 
     
     
         10 . (New claim) The spindle motor recited in  claim 9 , wherein said compound bearing apparatus is configured so that said outer peripheral labyrinth recess, said space defined between said shoulder and said inner end of the inner race, said first inner sealing plate and said second inner sealing plate cooperate to reduce dispersion of lubricant from said rolling bodies into a space between said two rows of rotating bodies.  
     
     
         11 . (Based on Original  claim 9)  A swing arm assembly journalled rotatably on a base of a hard disk drive device through a compound bearing apparatus provided within a base cylindrical portion of a swing arm said compound bearing apparatus comprising: 
 a stepped shaft having enlarged diameter shaft portion and reduced diameter shaft portion, a sleeve outer race surrounding the stepped shaft, and two rows of rotating bodies interposed therebetween, wherein: 
 the rotating bodies of the first row are disposed between an outer peripheral rolling recess formed directly on an outer peripheral surface of the enlarged diameter shaft portion and a first inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 the rotating bodies of the second row are disposed between an outer peripheral rolling recess formed on an outer periphery of an inner race fitted over the reduced diameter shaft portion of said stepped shaft and a second inner peripheral rolling recess formed directly on the inner peripheral surface of the sleeve outer race,  
 a space defined between a shoulder, formed at a point of transition from the enlarged diameter shaft portion to the reduced diameter shaft portion, and an inner end of the inner race,  
 at the longitudinal outer and inner side of the rotating bodies of the first row, a pair of first outer and inner sealing plates of ring shape having a central aperture respectively are fitted at their inner peripheries into a pair of peripheral grooves formed on each side of the peripheral rolling recess formed on the outer peripheral surface of the enlarged diameter shaft portion so as to be faced opposite to a pair of outer and inner peripheral grooves formed on each side of the first inner peripheral rolling recess of the sleeve outer race respectively,  
 the outer diameter of the central aperture is substantially equal to or larger than the inner diameter of the sleeve outer race and smaller than the outer diameter of the inner peripheral grooves respectively to prevent the first inner and second sealing plates from contact with the sleeve outer race to provide a labyrinth seal function,  
 at the longitudinal outer side of the rotating bodies of the second row, a second outer sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into a peripheral groove formed on the outer side of the second inner peripheral rolling recess formed on the inner peripheral surface of the sleeve outer race so as to be faced opposite to an outer side of the inner race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second outer sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function,  
 at the longitudinal inner side of the rotating bodies of the second row, a second inner sealing plate of ring shape having a central aperture is fixedly fitted at its outer periphery into a peripheral groove formed on inner side of the second inner peripheral rolling recess formed on the inner peripheral surface of the sleeve outer race so as to be faced opposite to the space between the stepped shaft and the inner race,  
 the inner diameter of the central aperture is substantially equal to or smaller than the outer diameter of the inner race and larger than the outer diameter of the reduced diameter shaft portion of the stepped shaft to prevent the second inner sealing plate from contact with the stepped shaft or the inner race to provide a labyrinth seal function.  
 
 
     
     
         12 . (New claim) The swing arm assembly recited in  claim 11 , wherein said compound bearing apparatus is configured so that said outer peripheral labyrinth recess, said space defined between said shoulder and said inner end of the inner race, said first inner sealing plate and said second inner sealing plate cooperate to reduce dispersion of lubricant from said rolling bodies into a space between said two rows of rotating bodies.