Downhole oil-sealed bearing pack assembly

Abstract

A downhole oil-sealed bearing pack assembly is provided for protecting bearing elements and seals. The bearing pack assembly includes a non-contact flow restrictor for reducing large differential pressures across sealing elements. The non-contact flow restrictor includes an inner restrictive element attached to a rotatable drive shaft and an outer restrictive element secured to a stationary bearing housing. The inner restrictive element can include an outwardly extending ring adjacent to a first land and the outer restrictive element can include an inwardly extending ring adjacent to a second land. During rotation of the drive shaft the inwardly and outwardly extending rings remain a distance from the second and first lands, respectively, thus permitting a fluid to traverse the rings and lands. The invention also provides a wear sleeve for increasing seal and shaft life. The wear sleeve includes a groove cut into a hollow sleeve which is secured to the rotatable driveshaft. A cooling fluid within the groove dissipates heat generated by seals contacting the wear sleeve on the rotating shaft. Further, a piston and dipstick assembly is provided for supplying oil to bearing elements and for measuring oil within a reservoir. The piston and dipstick assembly includes a chamber for containing oil and a drilling fluid. A floating piston applies pressure to the oil in the chamber and prevents the drilling fluid from mixing with the oil. A conduit extending into the chamber permits a dipstick to measure the location of the piston within the chamber to determine the amount of oil remaining within the chamber.