US Patent 7578663 Combined pump with rotodynamic impeller

The combined pump is a novel pumping system for fluids (liquids, gases) and for multiple-phase mixtures. This combined pump comprises a helical rotor on which a rotodynamic impeller is mounted. The helical rotor and impeller turns without touching inside a helical stator, and this helical rotor/impeller assembly and stator are arranged so that the cavities formed move from the suction toward the discharge. Using the rotodynamic impeller, the combined pump provides a pressurized fluid layer between the helical rotor/impeller assembly and the stator under conditions capable of improving the performances and the reliability of the pump.