DOWNHOLE TORQUE-GENERATING AND GENERATOR COMBINATION APPARATUS

摘要

A combination of a torque-generating apparatus with an alternator/generator. The torque-generating apparatus comprises a first assembly (10, 25) including a generally cylindrical member of magnetically soft material and having a longitudinal axis, and a second assembly (2) arranged coaxially within the first assembly and including an electromagnetic winding (4). The first assembly (10, 25) and the second assembly (2) are rotatable relative to each other about the axis. Relative rotation between the first (10, 25) and second (2) assemblies induces a magnetic field which generates rotational torque between the first and second assemblies. Rectification means (31) is provided to convert alternating current electrical output from the alternator/generator (22) to provide D.C. current to the electromagnetic windings (4) of the torque generating apparatus to generate an electromagnetic braking effect.