Shaft seal and bearing members for a rotary screw compressor

摘要

A screw rotor machine comprises a pair of intermeshing rotors (3) having helical lands and intervening grooves and a casing with a working space generally comprised of two intersecting bores, each enclosing one of the rotors (3). Each rotor (3) has a cylindrical projection (9) passing through a hole (8) in an end wall (5) at the high pressure end of the machine into a bearing chamber. To prevent gas leakage from the working space to the bearing chamber there is provided an annular element (15; 23) surrounding each rotor projection (9) and non-rotatably fixed to the casing. The annular element is provided with one axial (19; 24) and one radial (20; 21) sealing surface, one surface (19; 21) cooperating with the casing and the other surface (20; 24) cooperating with the rotor projection (9) by a slight or zero contact force. The annular element (15; 23) is movable almost without friction in the direction of the contact force. Since the annular element (15; 23) has only one radial sealing surface (20; 21), cooperating with either the rotor projection (9) or the casing, the annular element will seal effectively even if the axis of the hole (8) in the end wall (5) and that of the rotor projection (9) are non-aligned.