SCREW DOWNHOLE MOTOR Russian patent published in 2007 - IPC E21B4/02 F01C1/107 F04C2/107 

FIELD: drilling equipment, particularly fluid rotary type drives.

SUBSTANCE: downhole motor comprises support unit, stator with inner helical teeth covered with rubber and rotor with outer helical teeth. Number of rotor teeth is one tooth smaller than that of stator. Rotor axis is offset with respect to stator axis through distance equal to eccentricity value. The eccentricity value is equal to half of radial tooth height. Profiles of outer rotor teeth and profiles of inner stator teeth defined in end section envelope each other. Leads of rotor and stator tooth helixes are proportional to number of teeth. At least one of rotor or stator tooth has one or several transversal channels for periodic working fluid circulation between adjacent depressions of helical tooth during motor operation. Transversal channels are located from one rotor or stator side and extend along motor axis.

EFFECT: increased drilling efficiency due to application of dynamic (pulsed) axial force to be transmitted to drilling bit to motor rotor along with simultaneous working fluid flow increase and working fluid oscillation initiation to improve well bottom flushing.

4 cl, 11 dwg