Patent ID: 8535028

Claim:
A downhole positive displacement motor comprising: (a) an upper cylindrical housing having a connection adapted to connect to a hydraulic fluid source, and defining a central bore; (b) an upper valve assembly disposed within the upper housing, comprising a rotating cylindrical valve defining a plurality of longitudinal inlet passages numbering x, and a stationary cylindrical valve adjacent the rotating valve and defining a plurality of longitudinal transfer passages numbering x+1, configured such that when one inlet passage is wholly aligned with a transfer passage, at least one other inlet passage is partially aligned with another transfer passage; (c) a stator defining an internal passage having a plurality of lobe openings equal to x+1, which lobe openings are aligned with the longitudinal passages of the upper stationary valve; (d) a rotor comprising x lobes disposed within the stator, the rotor being eccentrically rotatable within the stator; (e) a lower valve assembly comprising a lower stationary cylindrical valve adjacent the rotor and defining a plurality of longitudinal transfer passages numbering x+1, and a lower rotating cylindrical valve defining a plurality of longitudinal exhaust passages numbering x, configured such that one lower exhaust passage is wholly aligned with a lower transfer passage, at least one lower exhaust passage is partially aligned with a lower transfer passage; (f) wherein the rotor and stator are disposed between the upper stationary valve and the lower stationary valve, and define a plurality of power pockets between the rotor and stator as the rotor rotates within the stator; (g) an upper drive mechanism connected to the rotor for rotating the upper rotating valve, and a lower drive mechanism connected to the rotor for rotating the lower rotating valve; and (h) a drive mechanism connected to the rotor or the lower rotating valve for driving a downhole tool.