SCREW DOWNHOLE MOTOR Russian patent published in 2006 - IPC E21B4/02 F01C1/16 F01C5/04 

FIELD: drilling equipment, namely, screw downhole motors for drilling and repairing oil and gas wells, possible use also in screw pumps for extracting oil and pumping liquid.

SUBSTANCE: screw downhole motor contains stator with internal screw teeth, faced with resiliently elastic material, rubber for example, and rotor with external screw teeth, number of which is one less than number of teeth of stator, while axis of rotor is displaced relatively to axis of stator for eccentricity value, equal to half of radial height of teeth, profiles of external teeth of rotor and internal teeth of stator in end cross-section are made with mutually possible bending around, while drives of screw teeth of rotor and stator are proportional to their number of teeth. Stator is made of two metallic layers, positioned concentrically, immoveable relatively to one another, external and internal layers having different melting temperature, while external layer of stator is made of steel or titanium alloy, and internal layer of stator with internal surface shaping teeth of stator is made of alloy with melting temperature equal to 0,1-0,8 of melting temperature of external layer of stator and with heat conductivity coefficient equal to 1,2-8,5 of heat conductivity coefficient of external layer of stator, for example, alloy based on zinc, aluminum or copper. Internal layer of stator with internal surface shaping teeth of stator is held relatively to external layer of stator by direct pouring of liquid melt of material of internal layer of stator into external layer of stator. Internal layer of stator with internal surface shaping teeth of stator is additionally held mechanically relatively to external layer, for example by pins or presence of eccentric surfaces on internal surface of external layer of stator or volumetric filling by material of internal layer of stator of recesses in rough internal surface of external layer of stator, while roughness of internal surface of external layer of stator is made in form of shelves and grooves of triangular or other shape, or in form of screw grooves of, for example, opposite directions.

EFFECT: increased resource and reliability of screw downhole motor during operation, simplified technology of manufacture of motor, increased working momentum and increased efficiency of motor.

3 cl, 3 dwg