Underneath a car’s hood is a belt-driven air conditioning compressor clutch. When that compressor is required to turn on, an electromagnetic clutch is used. These clutches transmit torque mechanically, but are actuated electrically. Most electromagnetic clutches have a single north to south pole magnetic connection, but these clutches have a special three-loop magnetic connection called a triple flux design. Slots in the armature and the rotor are offset, creating multiple points of magnetic contact. This multiplies attraction points, which increases the clutch’s torque creating a very efficient torque-to-weight ratio that is critical in vehicle applications.
Besides an air conditioning compressor, these clutches have also been used to run under-hood air pumps, hydraulic pumps, fans, and electric generators.
The clutch design shown from Ogura is the least expensive design. It uses a basic steel-on-steel rotor and leaf springs that are either set up to run clockwise or counter clockwise. The latest designs incorporate rubber dampening in the armature. This absorbs vibration between the input belt and the air conditioning compressor. These dampened armatures can come in a 3-eye, 5-eye, or a one-piece molded ring to provide vibration dampening.
For applications that require greater torque, friction material can be added to the rotor surface. Lastly, the coil can also be upgraded to injection-molded, which includes over-molding of the terminal assembly for a watertight coil.