Method of manufacturing a bearing unit, and a motor having loaded thereon the bearing unit

Abstract

A bearing unit includes an indent portion arranged on a portion of an inner circumferential surface of a housing to receive an oil supplying component. When inserting the oil supplying component, which is bent into a substantially round shape, a distance between a central axis of the housing and a center point of the inner circumferential surface of the substantially round-shaped oil supplying component is shorter than a radius of the inner circumferential surface of the housing. As a result of this unique arrangement, the inner circumferential surface of the oil supplying component securely makes contact with an outer circumferential surface of a sleeve of the bearing unit.

1 . A manufacturing method of a bearing unit, the bearing unit comprising: 
 a shaft;    a sleeve made of a sintered material impregnated with oil, and having a substantially cylindrical shape and an inner circumferential surface arranged to rotatably support the shaft;    a housing having an inner circumferential surface arranged to radially surround and support the sleeve, wherein the housing includes at the inner circumferential surface a ring shaped indent portion extending in a radially outward direction; and    an oil supplying component retained in the indent portion and making contact with an outer circumferential surface of the sleeve so as to supply oil to the sleeve; wherein    the manufacturing method of the bearing unit comprises the steps of:    a) inserting the oil supplying component into the indent portion such that at least a portion of an inner circumferential surface of the oil supplying component is located closer to a central axis of the housing than an inner circumferential surface of the housing is to the central axis;    b) inserting the sleeve into the housing; and    c) inserting the shaft into the sleeve.    
   
   
       2 . The manufacturing method of the bearing unit according to  claim 1 , wherein the oil supplying component is made of a flexible material, and the oil supplying component is bent into a substantially round shape in step a) in order to be inserted into the indent portion.  
   
   
       3 . The manufacturing method of the bearing unit according to  claim 1 , wherein the oil supplying component is made of a textile material.  
   
   
       4 . The manufacturing method of the bearing unit according to  claim 1 , wherein at least one of a top surface and a bottom surface formed in a space between the inner circumferential surface of the housing and an inner circumferential surface of the indent portion includes an inclined surface extending in an axial direction.  
   
   
       5 . The manufacturing method of the bearing unit according to  claim 2 , further comprising soaking the oil supplying component with the oil after the step a).  
   
   
       6 . The manufacturing method of the bearing unit according to  claim 2 , wherein a center point along the inner circumferential surface of the substantially round-shaped oil supplying component is located closer to the central axis than the inner circumferential surface of the housing is to the central axis.  
   
   
       7 . The manufacturing method of the bearing unit according to  claim 2 , wherein a depth of the indent portion in a radial direction is substantially identical to a thickness of the oil supplying component.  
   
   
       8 . The manufacturing method of the bearing unit according to  claim 2 , wherein a gap is provided between an outer circumferential surface of the oil supplying component and the inner circumferential surface of the indent portion in the step a).  
   
   
       9 . The manufacturing method of the bearing unit according to  claim 2 , wherein a first end of the oil supplying component does not contact a second end of the oil supplying component when the oil supplying component is arranged in the indent portion.  
   
   
       10 . A motor having attached therein the bearing unit manufactured in accordance with  claim 1 , the motor comprising: 
 a rotor portion affixed to one end of the shaft and having a rotor magnet; and    a stator portion affixed to an outer circumferential surface of the housing and arranged to oppose the rotor magnet.    
   
   
       11 . The motor according to  claim 10 , wherein the rotor portion includes a color wheel mounted thereto.  
   
   
       12 . A manufacturing method of a bearing unit, the bearing unit comprising: 
 a shaft;    a sleeve made of a sintered material impregnated with oil, and having a substantially cylindrical shape and an inner circumferential surface arranged to rotatably support the shaft;    a housing having an inner circumferential surface arranged to radially surround and support the sleeve, wherein the housing includes at the inner circumferential surface a ring shaped indent portion extending in a radially outward direction; and    an oil supplying component retained in the indent portion and making contact with an outer circumferential surface of the sleeve so as to supply oil to the sleeve; wherein    the manufacturing method of the bearing unit comprises the steps of:    inserting the oil supplying component into the indent portion;    inserting the sleeve into the housing such that at least one radius from a central axis of the housing to an inner circumferential of the oil supplying component is shorter than a radius from the central axis to an outer circumferential surface of the sleeve; and    inserting the shaft into the sleeve.    
   
   
       13 . A motor having attached therein the bearing unit manufactured in accordance with  claim 12 , the motor comprising a rotor portion affixed to a first end of the shaft and having a rotor magnet, and a stator portion affixed on an outer circumferential surface of the housing and opposing the rotor magnet.  
   
   
       14 . The motor according to  claim 13 , wherein the rotor portion includes a color wheel attached thereto.  
   
   
       15 . A display unit comprising: 
 a motor according to  claim 10;     a color wheel assembly including a rotary color wheel driven by the motor, the color wheel including color filters arranged to project and display a color picture image;    a digital micro mirror device arranged to reflect a light transmitted through the color wheel by movable mirrors;    a projection optical system arranged to project the light reflected from the digital micro mirror device onto a screen; and    a case arranged to house the color wheel assembly, the light source, the digital micro mirror device, and the projection optical system.    
   
   
       16 . A display unit comprising: 
 a motor according to  claim 13;     a color wheel assembly including a rotary color wheel driven by the motor, the color wheel including color filters arranged to project and display a color picture image;    a digital micro mirror device arranged to reflect a light transmitted through the color wheel by movable mirrors;    a projection optical system arranged to project the light reflected from the digital micro mirror device onto a screen; and    a case arranged to house the color wheel assembly, the light source, the digital micro mirror device, and the projection optical system.