Magnetic powder clutch

An electromagnetic clutch (110) for an air conditioning compressor includes a generally cylindrical pulley (111) rotatably mounted on a comressor housing (116) and having an annular friction surface (120a, 120b) in a cavity (120). A driven member (112) is mounted on a compressor shaft (113) and has a leg (118, 119) with an annular friction surface (118a, 118b, 119a, 119b) positioned radially adjacent the cavity friction surface to form an annular space (120c, 120f) therebetween. A quantity of flowable magnetic material (127) is provided in the annular space and a magnetic coil (124) is fixed on the housing adjacent thereto. When electrical power is applied to the magnetic coil (124), magnetic flux is generated in the annular space (120c, 120f) polarizing the magnetic material and frictionally coupling the friction surfaces to cause the pulley (111) to rotate the driven member (112). A divider (123) can be positioned between the legs (118, 119) to provide additional annular spaces (120d, 120e) for the magnetic material (127).