DOWNHOLE MOTOR Russian patent published in 2006 - IPC E21B4/02 

FIELD: drilling equipment, particularly downhole motors adapted for oil and gas well drilling and repair.

SUBSTANCE: downhole motor comprises moving section, spindle section, through bush fixed relatively body and provided with inner channels. Spindle section includes body, hollow output shaft, thrust bearing, upper and lower radial bearings. The through bush is installed over upper radial bearing in front of window adapted to permit working fluid flow passage into hollow output shaft. The bush may periodically close windows during downhole motor operation. Upper radial bearing and through bush are spaced from output shaft and define radial gap in-between. Annular cavity communicating with the radial gap of through bush and radial gap of upper radial bearing is created between the through bush and upper radial bearing. Annular cavity is defined by recess created in at least one bush of upper radial bearing at upper bearing end. The recess radially converges in working flow direction through upper radial bearing towards lower radial bearing to obtain radial bearing gap dimensions and/or annular cavity between through bush and upper radial bearing is defined by additional bush installed in-between, wherein the additional bush is fixed with respect to the body. Annular cavity may be also created by annular depression made in inner working surface of through bush from lower end side. Thrust motor bearing may provide axial sliding of hollow output shaft in axial direction to provide hollow output shaft windows displacement outside inner through bush surface towards annular cavity during idle motor operation without periodical closing of hollow output shaft windows.

EFFECT: increased service life of thrust and radial downhole motor bearings, reduced well drilling costs and decreased number of trips for motor repair.

5 cl, 6 dwg