Patent ID: 8047549

Claim:
A magnetic fluid shaft-sealing device comprising, in combination: a seal cover ( 3 ) including inner and outer end faces ( 31 , 32 ) spaced along an axis, with the inner end face ( 31 ) of the seal cover ( 3 ) being adapted to be attached to an end ( 11 ) of a pump housing ( 1 ), with the seal cover ( 3 ) further including a shaft hole ( 33 ) extending from the inner end face ( 31 ) through the outer end face ( 32 ) along the axis, with the seal cover ( 3 ) further including an annular recess ( 36 ) formed in the outer end face ( 32 ) and around the shaft hole ( 33 ), with an inner ring portion ( 363 ) being defined between the annular recess ( 36 ) and the shaft hole ( 33 ), and with the inner ring portion ( 363 ) having an outer periphery ( 364 ) defining an inner wall face of the annular recess ( 36 ); a collar ( 4 ) adapted to be mounted around a rotary shaft ( 2 ) in the pump housing ( 1 ) to rotate therewith, with the collar ( 4 ) including a first end ( 41 ) received in the annular recess ( 36 ) and around the inner ring portion ( 363 ) of the seal cover ( 3 ), with the collar ( 4 ) further including a second end ( 42 ) spaced from the first end ( 41 ) of the collar ( 4 ) along the axis, with the collar ( 4 ) further including a longitudinal hole ( 43 ) extending from the first end ( 41 ) through the second end ( 42 ) of the collar ( 4 ) and coaxial with the axis, with the rotary shaft ( 2 ) extending through the longitudinal hole ( 43 ) of the collar ( 4 ) and the shaft hole ( 33 ) of the seal cover ( 3 ), and with the first end ( 41 ) of the collar ( 4 ) including an annular inner periphery ( 440 ) having a spacing to the outer periphery ( 364 ) of the inner ring portion ( 363 ) of the seal cover ( 3 ) in a radial direction perpendicular to the axis; a first magnet ( 6 ) mounted between the outer periphery ( 364 ) of the inner ring portion ( 363 ) of the seal cover ( 3 ) and the first end ( 41 ) of the collar ( 4 ); first and second pole pieces ( 5 ) mounted between the outer periphery ( 364 ) of the inner ring portion ( 363 ) of the seal cover ( 3 ) and the first end ( 41 ) of the collar ( 4 ), with the first magnet ( 6 ) being sandwiched between the first and second pole pieces ( 5 ), and with a first gap ( 71 ) being formed between the inner periphery ( 440 ) of the first end ( 41 ) of the collar ( 4 ) and outer peripheries of the first and second pole pieces ( 5 ); and a first magnetic liquid ( 7 ) filled in the first gap ( 71 ) to provide a liquid seal between the inner periphery ( 440 ) of the first end ( 41 ) of the collar ( 4 ) and the outer peripheries of the first and second pole pieces ( 5 ).