GB665565A - Improvements in or relating to displacement engines of the helical screw wheel type - Google Patents

Abstract

665,565. Meshing-screw engines or compressors. AKTIEBOLAGET LJUNGSTROMS ANGTURBIN. July 29, 1949 [Aug. 4, 1948], No. 19969/49. Class 110(ii) A housing, having at least two intersecting cylindrical bores for the screw rotors, comprises an inner casing 16, surrounding the rotors, provided with flanges 26, 28, 62 having substantially circular outer peripheries around which an outer jacket is secured. Fins are provided on the inner casing around its periphery and in the neighbourhood of the inlet and outlet ports and air, to be used in the engine, is circulated between the fins and casing walls, for cooling purposes. Each inner casing may be built of two or more sections which are forged or rolled and of light weight. Cooling passages are provided through the screw rotors. Plates 26, 28 are placed at the ends of the working chambers which are provided with working fluid inlet and outlet ports 22, 24. Cooling air enters through a port 66 for cooling the plate 26 and the working fluid inlet 70 and flows to chamber 96 and through a port 122 to inside guide plates 54 and into the cooling ducts 56 leading to a chamber 114. The inlet 70 has cooling fins 110, outside which is a guide plate 112 and part of the cooling air is led around these fins to the chamber 114 by way of a port 116, and through a duct 56 by way of a port 118. Finally the air is led through a duct 124 to a chamber 126 having an outlet 128. In a modified arrangement, Fig. 8 (not shown) the outer jacket is part circular but cut by a plane parallel with the rotor shafts wherein lies the engine outlet port. A further arrangement, Fig. 11, shows a housing construction built solely of sheet metal with inner and outer casings. The inner casing 16 consists of six similar members surrounding two pairs of engine rotors. Reinforcing and cooling flanges 52 are provided. Working fluid is supplied to the respective engines through inlet ducts 312, 314 leading to triangular apertures 316, 318 provided with cooling fins. A chamber 300 leads to two exhaust ports 308, 310 in an end wall. An outer jacket 48 is placed externally on the flanges 52 to form a cooling chamber having inlets 330a and 330b and outlets 332a and 332b. In a modification, Fig. 16 (not shown), part of the housing is of conical shape internally so that an outlet will be open all along the opening edges of a helical screw thread simultaneously.