Bearing unit, and motor using same

Abstract

A bearing unit is provided which includes a shaft ( 51 ) to support rotatably, radial bearing ( 55 ) to support the shaft ( 51 ) circumferentially, a thrust bearing ( 66 ) to support the shaft ( 51 ) in the direction of thrusting, and a housing ( 56 ) having the radial bearing ( 55 ) and thrust bearing ( 66 ) disposed therein and in which a viscous fluid ( 57 ) is filled. The housing ( 56 ) has a sealed structure except for a shaft insertion hole ( 65 ) formed therein and through which the shaft 51 is introduced. Between the outer surface of the shaft ( 51 ) and the inner surface of the shaft insertion hole ( 65 ), there is defined a gap ( 69 ) having a sufficient width to prevent the viscous fluid ( 57 ) filled in the housing ( 56 ) from leaking out of the latter.

1 . A bearing unit comprising:
 a shaft;   a radial bearing to support the shaft circumferentially;   a thrust bearing to support the shaft at one of the thrusting-directional ends thereof; and   a housing in which the radial and thrust bearings supporting the shaft are disposed and a viscous fluid is filled;   the housing having a hermetic structure except for a shaft insertion hole receiving the shaft therein and in which there is defined between the outer surface of the shaft and the inner surface of the shaft insertion hole a gap having a sufficient width to prevent the viscous fluid filled in the housing from leaking to outside,   wherein the end portion of the housing where the thrust bearing is disposed is formed from a synthetic resin and joined by welding to the housing body also formed from the synthetic resin and in which the radial bearing is disposed,   wherein the thrust bearing supports a projecting portion formed at one end of the shaft and which is larger in diameter than the shaft body, and has formed in the surface thereof opposite to the projecting portion of the shaft dynamic pressure producing recesses to produce a dynamic pressure by the viscous fluid.   
     
     
         2 . A bearing unit comprising:
 a shaft;   a radial bearing to support the shaft circumferentially;   a thrust bearing to support the shaft at one of the thrusting-directional ends thereof; and   a housing in which the radial and thrust bearings supporting the shaft are disposed and a viscous fluid is filled;   the housing having a hermetic structure except for a shaft insertion hole receiving the shaft therein and in which there is defined between the outer surface of the shaft and the inner surface of the shaft insertion hole a gap having a sufficient width to prevent the viscous fluid filled in the housing from leaking to outside the housing,   wherein the end portion of the housing where the thrust bearing is disposed is formed, by outsert molding, integrally on the housing body in which the radial bearing is disposed,   wherein there is provided inside the housing a come-off preventive portion to prevent the shaft from coming off in the direction of thrusting through the shaft insertion hole.   
     
     
         3 . A motor including a bearing unit supporting a rotor of the motor rotatably in relation to a stator of the motor, the bearing unit comprising:
 a shaft;   a radial bearing to support the shaft circumferentially;   a thrust bearing to support the shaft at one of the thrusting-directional ends thereof; and   a housing in which the radial and thrust bearings supporting the shaft are disposed and a viscous fluid is filled;   the housing having a hermetic structure except for a shaft insertion hole receiving the shaft therein and in which there is defined between the outer surface of the shaft and the inner surface of the shaft insertion hole a gap having a sufficient width to prevent the viscous fluid filled in the housing from leaking to outside,   wherein the end portion of the housing where the thrust bearing is disposed is formed from a synthetic resin and joined by welding to the housing body also formed from the synthetic resin and in which the radial bearing is disposed,   wherein the thrust bearing supports a projecting portion formed at one end of the shaft and which is larger in diameter than the shaft body, and has formed in the surface thereof opposite to the projecting portion of the shaft dynamic pressure producing recesses to produce a dynamic pressure by the viscous fluid,   wherein the rotor is supported by the housing and rotates along with the housing.   
     
     
         4 . The motor as set forth in  claim 3 , wherein a shaft insertion hole extends through said housing, a portion of said shaft extending through said shaft insertion hole. 
     
     
         5 . The motor as set forth in  claim 3 , wherein said radial bearing supports said shaft circumferentially. 
     
     
         6 . The motor as set forth in  claim 3 , wherein said a thrust bearing supports said shaft at one of the thrusting-directional ends thereof. 
     
     
         7 . The motor as set forth in  claim 6 , wherein said thrust bearing is disposed within said housing. 
     
     
         8 . The motor as set forth in  claim 6 , wherein said thrust bearing is between said housing and a projecting portion, said projecting portion being at an end of said shaft opposite to said fixing portion. 
     
     
         9 . The motor as set forth in  claim 8 , wherein said shaft and said projecting portion are metal. 
     
     
         10 . The motor as set forth in  claim 8 , wherein said projecting portion is larger in diameter than said shaft body. 
     
     
         11 . The motor as set forth in  claim 8 , wherein dynamic pressure producing recesses are within a surface of said thrust bearing, said surface being opposite to said projecting portion. 
     
     
         12 . The motor as set forth in  claim 11 , wherein said housing is filled with a viscous fluid, said dynamic pressure producing recesses being configured to produce a dynamic pressure by said viscous fluid. 
     
     
         13 . The motor as set forth in  claim 3 , wherein an engagement hole extends through said rotor, an engagement portion of the bearing unit being press-fitted in said engagement hole. 
     
     
         14 . The motor as set forth in  claim 13 , wherein an outer surface of said engagement portion is correspondingly stepped to an inner surface of said engagement hole. 
     
     
         15 . A motor including a bearing unit supporting a rotor of the motor rotatably in relation to a stator of the motor, the bearing unit comprising:
 a shaft;   a radial bearing to support the shaft circumferentially;   a thrust bearing to support the shaft at one of the thrusting-directional ends thereof; and   a housing in which the radial and thrust bearings supporting the shaft are disposed and a viscous fluid is filled;   the housing having a hermetic structure except for a shaft insertion hole receiving the shaft therein and in which there is defined between the outer surface of the shaft and the inner surface of the shaft insertion hole a gap having a sufficient width to prevent the viscous fluid filled in the housing from leaking to outside the housing,   wherein the end portion of the housing where the thrust bearing is disposed is formed, by outsert molding, integrally on the housing body in which the radial bearing is disposed,   wherein there is provided inside the housing a come-off preventive portion to prevent the shaft from coming off in the direction of thrusting through the shaft insertion hole,   wherein the rotor is supported by the housing and rotates along with the housing.   
     
     
         16 . The motor as set forth in  claim 15 , wherein a shaft insertion hole extends through said housing, a portion of said shaft extending through said shaft insertion hole. 
     
     
         17 . The motor as set forth in  claim 15 , wherein said radial bearing supports said shaft circumferentially. 
     
     
         18 . The motor as set forth in  claim 15 , wherein said a thrust bearing supports said shaft at one of the thrusting-directional ends thereof. 
     
     
         19 . The motor as set forth in  claim 18 , wherein said thrust bearing is disposed within said housing. 
     
     
         20 . The motor as set forth in  claim 18 , wherein said thrust bearing is between said housing and a projecting portion, said projecting portion being at an end of said shaft opposite to said fixing portion. 
     
     
         21 . The motor as set forth in  claim 20 , wherein said shaft and said projecting portion are metal. 
     
     
         22 . The motor as set forth in  claim 20 , wherein said projecting portion is larger in diameter than said shaft body. 
     
     
         23 . The motor as set forth in  claim 20 , wherein dynamic pressure producing recesses are within a surface of said thrust bearing, said surface being opposite to said projecting portion. 
     
     
         24 . The motor as set forth in  claim 23 , wherein said housing is filled with a viscous fluid, said dynamic pressure producing recesses being configured to produce a dynamic pressure by said viscous fluid. 
     
     
         25 . The motor as set forth in  claim 15 , wherein an engagement hole extends through said rotor, an engagement portion of the bearing unit being press-fitted in said engagement hole. 
     
     
         26 . The motor as set forth in  claim 25 , wherein an outer surface of said engagement portion is correspondingly stepped to an inner surface of said engagement hole.