Patent ID: 8109721

Claim:
A bearing arrangement for a turbine rotor of a turbine adapted to be mounted in a drill string and to be driven by the flow of drilling fluid, comprising: a turbine chamber surrounding the turbine rotor and having an inflow side and an outflow side, a stator with an axle on which the turbine rotor is rotatably mounted, a cavity formed between the turbine rotor and the stator and accommodating at least one radial plain bearing and being separated from the turbine chamber by a first constriction and a second constriction, the first and second constrictions being relatively spaced and formed between the stator and the turbine rotor, an axial plain bearing constructed as a bearing ring seal which provides the first constriction, and a conveyor screw mounted on the turbine rotor and providing the second constriction, said conveyor screw operating to convey from the cavity to the turbine chamber, wherein the axial plain bearing has a first bearing ring mounted on the turbine rotor and a second bearing ring mounted on the stator, wherein the first bearing ring has a first annular bearing surface and the second bearing ring has a second annular bearing surface, the first and second bearing rings resting against each other with the first annular bearing surface and the second annular bearing surface, and wherein at least one of the first annular bearing surface and the second annular bearing surface has at least one concentric annular surface dividing the at least one of the first annular bearing surface and the second annular bearing surface into a radially outer annular bearing surface portion and a radially inner annular bearing surface portion.