Shaft mounted eddy current drive with rotary electrical connector

Abstract

An electric variable speed drive includes a hub member, a driven member, a magnetic coupler, and a rotary electrical connector. The hub member is mounted for rotating with the shaft of a prime mover. The driven member is rotatably supported on the hub member by bearings, and includes a mechanical output portion such as a pulley. The magnetic coupler includes an electric coil and magnetic poles which are mounted for rotating with one of the hub and the driven members. An armature is mounted to the other of the hub and driven members. An electric current is passed through the electric coil to magnetically couple the hub member to the driven member. The extent of the magnetic coupling between the hub and driven members is determined by the electric current passing through the electric coil. The rotary electrical connector includes a conductive fluid, such as liquid mercury, which extends between stationary and rotary contacts for passing the electric current from a stationary power source to the rotating electric coil. A fan and heater maintain the temperature of the rotary electrical connector between minimum and maximum operating temperature limits. Insulation prevents heat generated in operating the drive from raising the temperature of the rotary electrical connector.