GB464476A - Improvements in rotary engines - Google Patents

Abstract

464,476. Meshing-screw engines. AKTIEBOLAGET MILO. Oct. 16, 1935, No. 28618. Convention date, Feb. 12. [A Specification was laid open to inspection under Sect. 91 of the Acts, April 17, 1936.] [Class 110 (ii)] The engine or compressor has rotors 410, 412, geared externally by gears 442, 444, so that the helical threads on the rotor do not make contact with one another. The pressure side a of a convex thread has a smaller radius of curvature than the curve b on the suction side (in the case of a compressor). Roller bearings 416, 418, take up the radial pressure, and ball bearings 424 the axial pressure. Internal cooling of the rotors is secured by means of holllow shafts provided with concentric internal tubes 446, 448, respectively. Cooling liquid is introduced by nozzles 450 into the interior tubes, and returns outside these tubes into the spaces 460. Inlet and outlet ports 462, 464, for the compressor, are provided. Radial bores 466, 470, prevent suction of lubricant into the compressor casing, and penetration of compressed medium into the bearings at the H.P. end, respectively. The top circle 474 of the smaller rotor, and the root circle of the greater rotor, coincide with the pitch circle. The constructions of a thread T and a recess R are described, to secure efficient meshing of the rotors. The rotors may be made shorter than the pitch of the threads, and the inlet and outlet ports extended to embrace parts of the end plates. Fig. 5 shows a view of the pressure end with a plate 502 provided to limit the edge of the delivery port. The bounding line of the axial port is described in the Specification, and is developed to fit the shapes of the threads and recesses of the rotors. Similarly the inlet port may be extended to embrace part of the end plate in the L.P. end. To prevent fluid being trapped by a tooth in a recess R, a small passage may be provided, which leads to the delivery port. In Fig. 1 the portion of the rotors located to the left of lines 510, 514, 512, is completely enclosed by the casing, while that to the right is in communication with the inlet 462.