Ferrofluid sealing apparatus for a reciprocating shaft

A ferrofluid sealing apparatus for a reciprocating shaft, in which the first bearing, the first magnetism isolating rings, the first pole piece, the first O-shaped rubber seal, a magnet, the second O-shaped rubber seal, the second pole piece, the second magnetism isolating ring, and the second bearing are sandwiched between the two inner bosses of the outer casing in series;

• an end cover is fixed on an outer casing by means of screws so as to press the second bearing;
• the ferrofluid is injected into the inner torus of the magnet during operation;
• the above sealing structure is installed on the reciprocating shaft plated with polytetrafluoroethylene,
• characterized in that
• there are provided with three step holes in the inner torus of the second pole piece (13) as left step hole, middle step hole, and right step hole, in which N+1 of elastic rings (T) and trapezoidal teeth (C) arranged closely within the interval of the middle step hole, where N is a positive integer in 1 to 8;
• the trapezoidal teeth (C) and the elastic rings (T) are connected with the second pole piece (13) by means of screws and shield rings (15);
• the N of the trapezoidal teeth (C) are arranged in the same expanding direction of their inner holes;
• the first pole piece (7) is provided to have the same structure as the second pole piece (13).