Patent ID: 6158996
Filing Date: 2000-12-12
Classification: F04C

Abstract:
A screw rotor set for screw pumps in an axially parallel arrangement engaging in opposite directions in the external axes and with wrap angles of at least 720.degree. in a single-thread construction, and with smooth plane-parallel rotor end faces, wherein each screw rotor consists of several individual parts fixed rigidly together with a common axis of rotation, with eccentric centre of gravity positions and with different material densities; the individual parts inside the rotor form an eccentric balancing cavity separable from the pump chamber; adjustment of the material density and the geometry of the individual parts inside the rotor cause static balancing and affect dynamic unbalance, and dynamic balancing is achieved with little effect on static unbalance by calculated determination of the screw length/pitch ratio=a at values which are close to but smaller than the next higher uneven multiple of 1/2.