Shaft seal and bearing members for a rotary screw compressor

In a screw rotor machine for a working fluid, comprising:

• 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), said casing having a low pressure end section (4), a high pressure end section (1) carrying bearings (10, 11, 12) for the rotors (3) and an intermediate barrel section (2), said intermediate barrel section (2) being connected to at least one of said end sections (1, 4) by means of a detachable joint, and said high pressure end section (1) being provided with a bearing chamber separated from the working space by an end wall (5) provided with a plurality of holes (8), each hole freely surrounding a cylindrical projection (9) of a rotor (3),
• the improvement comprising:
• a separate annular element (15) axially fixed with respect to said end section and surrounding each one of the respective rotor projections (9), the annular elements (15) each having a radial inner surface (20) which forms a sealing surface with a running clearance, said sealing surface cooperating with the respective rotor projection (9) by a very slight radial contact sealing force;
• the end section having a recess within which said annular element is free to move to a certain distance in the radial direction;
• and
• the annular elements (15) each being radially movable substantially without friction in the casing, always to maintain position alignment with the axis of the rotor projection, and being in axial sealing contact with the casing, the annular elements (15) each being non-rotatably fixed to the casing.