DOWNHOLE SCREW MOTOR GEARED-ROTOR MECHANISM Russian patent published in 2001 - IPC

FIELD: oil gas industries; well drilling. SUBSTANCE: invention can be used also in screw pumps for recovery of oil and transfer of liquids. Geared-rotor mechanism of downhole screw motor has stator with internal helical teeth made of elastic material and rotor with external helical teeth whose number is less than that of stator teeth by one. Profiles of external helical teeth of rotor and internal helical teeth of stator are made relatively envelopable in end face section. Leads of helical teeth of rotor and stator are proportional to their teeth number. Thickness C_t of stator tooth in pitch diameter of teeth and peripheral pitch S_t of teeth in end face section perpendicular to axis O₂O₂ of geared- rotor mechanism are related by equation C_t/S_t= 0,45÷0,65.> In normal section N-N perpendicular to direction of helix M-M of stator tooth, thickness C_N of tooth 2 of stator 1 in pitch diameter D_p of teeth and radial height h of stator tooth are related by equation C_N/h ≥ 1,75. EFFECT: improved performance characteristics, reliability and increased service life.