GB1448157A - Rotary positive displacement machines - Google Patents

Abstract

1448157 Rotary positive-displacement fluid-machines A I ABAIDULLIN I G KHISAMEEV A L VERNY A I SHVARTS V B SHNEPP and IGGALIAKHMETOV 11 April 1974 [17 April 1973(2)] 16186/74 Heading F1F A machine such as a gas compressor or expander has co-operating rotors 6, 7 with axially-straight teeth 14, 15, matching lobes 13 and depressions 17 and synchronizing gears, Fig.2 (not shown), the depressions equalizing the pressures in cavities 18 with that in a cavity 19. To prevent back-flow between discharge ports 4 and a suction-pipe connection 2 between the inter-meshing teeth, and also prevent compression in inter-tooth spaces 20 by the teeth 14, contact may be made between the teeth only along a line that travels from the crest of the tooth 14 towards its root, contact ceasing when the ports 4 are obturated by the respective tooth 15 and said crest reaches the plane containing the rotor axes, Fig. 6. The lobes 13 engage sealingly with the depressions 17 to obviate backflow therethrough. The profile of the trailing side of each tooth 14 may be a part of an epicycloid and the ratio of the height h above the pitch, or "rolling", circle (of radius r 2 ) to the breadth b of the leading portion of the tooth may be equal to or greater than unity. Preferably, the profiles of the leading sides 23, 24 and the crests and bases of the lobes and depressions are arcs of circles, details of which are given in the specification. The centre of curvature of the leading side of each depression may be upon the rolling circle (or radius r 1 ) or outside of this circle, Fig. 8 (not shown), the leading side of each lobe then being such that it rolls on the said side of the depression. Additional discharge ports may be provided at 31.