Positive displacement flowmeter with intermeshed rotors - has part-cycloid, part-trochoid profile vanes enabling rotors to move under pressure difference in fluid transfer conduit

摘要

A positive displacement flow meter has a pair of intermeshed screw shaped rotors (1, 2). The sectional profile of the rotor vanes comprises a cycloid portion containing a trochoid portion. One rotor (1) has four vanes, a second rotor (2) having three vanes. The rotors are free to move under a pressure difference in a fluid transfer passage (4, 4'). The outer periphery of the rotor sections is of circular form centred of the respective rotor axis (O1, O2) and in operation forms a seal with the body of the displacement meter (3). A pitch circle defines the locus (5, 7) of the transition point of the rotor section profile curves.