Abstract: The invention is directed to a turbine with a housing mountable in a drill string and having an inlet opening and an outlet opening for a fluid conveyed through the drill string, and with an impeller arranged in the housing and adapted to be impinged upon by the fluid flowing into the housing, wherein the impeller is axially movably mounted and yieldably supported against the afflux direction in such a way that the supporting force of the yielding support increases as the axial movement of the impeller increases. To reduce the dependence of the turbine rotational frequency and turbine performance on the feed rate and to avoid overloading of the generator, the housing includes in the range of movement of the impeller a frontal first housing section of smaller inner diameter as seen in the afflux direction and a rear second housing section of larger inner diameter as seen in the afflux direction.

Abstract: A bearing arrangement for a turbine rotor of a turbine is adapted to be mounted in a drill string and to be driven by the flow of drilling fluid. The bearing arrangement includes a turbine chamber surrounding the turbine rotor and having an inflow and an outflow, a stator on which the turbine rotor is rotatably mounted, and 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 an axial plain bearing constructed as a bearing ring seal and by a conveyor screw which is disposed on the turbine rotor and operates to convey from the cavity to the turbine chamber.

Abstract: The invention is directed to a turbine (3) for generating power in a drill string (2), including a turbine rotor (10) drivable by a fluid and a bypass device having a first bypass channel bypassing the turbine rotor (10). For varying the volumetric flow through the bypass channel, provision is made for a valve (28) and a control device driven by the fluid and having a drive element (24) by means of which the valve (28) is movable anywhere between a first and a second position. The drive element (24) produces a flow resistance in the fluid flow path downstream from the turbine rotor (10) and downstream from the valve (28) and in the flow direction takes support upon a spring (26).

Abstract: A controllable pressure reducing valve has a housing which includes an inner chamber extending in the direction of a longitudinal axis and an inlet opening and an outlet opening. The inlet opening and the outlet opening open into the inner chamber at an axial relative distance. The inner chamber includes between the mouths of the inlet opening and the outlet opening at least one annular wall having a cylindrical valve bore. An axially movable valve body which is arranged in the inner chamber, extends through the valve bore and has a piston-type portion guided in the valve bore and adapted to close the valve bore. The piston-type portion includes at least one control recess bounded by a control step which extends in axial direction and in circumferential direction and combines with an edge of the valve bore to form a controllable valve opening.