Ferrofluid sealing apparatus with small diameter used in low temperature

A ferrofluid sealing apparatus with small diameter used in low temperature, which comprises:

• a small end cover, a permeable casing, an outer casing, O-rings, bearings, adjusting shims, pole pieces, ferrofluid, a magnet, and a large end cover in which the first bearing (6), the first pole piece (10) installed with the first O-ring (11), the magnet (13), the second pole piece (15) installed with the second 0-ring (14), and the second bearing 17 are provided to abut against in series and are sandwiched between the two inner bosses of the outer casing (8);
• the large end cover (19) is installed on the outer casing (8) by means of screws so as to press the second bearing (17);
• the ferrofluid is injected into the inner torus of the magnet;
• the permeable casing (1) installed with the adjusting shim (20) is installed into the inner hole of the above assembled bearings and pole pieces;
• and the permeable casing (1) is fixed with the small end cover (5) using screws (4),
• characterized in that two groups of teeth (3) are provided on the outer cylindrical surface of the permeable casing (1);
• the parameters of the teeth are determined in such a way that the width is 0.5 mm, the height is 2.5 mm, and the width of the grooves is 1.5 mm;
• and
• the first magnetism isolating ring (9) is installed between the first bearing (6) and the first pole piece (10), while the second magnetism isolating ring (16) is installed between the second bearing (17) and the second pole piece (15).