SCREW ROTARY PUMP Russian patent published in 2010 - IPC F04D9/04 F04D13/04 

FIELD: engines and pumps.

SUBSTANCE: screw rotary pump comprises housings 5, 17, 19, impeller 2 with hub 3 fitted on shaft 1 running in bearing 4 packed by seal 32, and screw 10. Hub 3 accommodates intermediate and inner shafts 6, 8. One extension of inner shaft 8 carries first screw 10 locked by taper nut 11 on shaft 8. Impeller 12 of first hydraulic turbine is arranged on taper surface of nut 11. Second screw 13 and second turbine impeller 14 are fitted on extensions of intermediate shaft 6. Second turbine nozzle box 15 is arranged inside shaft 1. Hub 3 has through holes 25 communicating inside of impeller 2 with space of hub 3. Through hole 28 is made inside shaft 8 and nut11 to force pumped product unto cavity 18 before impeller 12 of first hydraulic turbine. Inside of shaft 1 has two chambers 27, 35 separated by baffle 34 with hole 36. Inside 35 of shaft 1 communicates inside 33 between bearing 4 and seal 32.

EFFECT: improved cavitation properties.

2 cl, 3 dwg