Drive hub with curved springs and drive keys for electro-magnetic clutch

Claim 1

In a magnetic clutch for driving a shaft including a rotatable element having a friction face positioned around and independent of the shaft, an armature disk positioned around the shaft and including a friction face in opposed relation to the friction face on the rotatable element, an electromagnet for selectively moving the friction faces into driving engagement, that improvement comprising a flexible drive coupling between the armature disk and drive shaft, said coupling comprising a plurality of arcuately curved leaf springs, each spring having one end connected with the armature disk, means drivingly connecting the other end of each spring with the shaft to enable flexibly resilient axial, radial and circumferential relative movement between the armature disk and drive shaft, said means drivingly connecting the springs and drive shaft comprising a hub affixed to the drive shaft and including a hub plate, the armature disk being positioned around the hub plate with the inner ends of the arcuately curved springs being connected to the hub plate, each of the springs being generally U-shaped and including an elongated central arcuate portion and radially inwardly offset ends anchored to said hub plate and armature disk, respectively, the end of each spring attached to the armature disk lying along a radius of the hub plate and armature disk and the end of the spring attached to the hub plate being disposed adjacent to but in slightly trailing relation to the same radius when the springs are not deflected, the central portion of each spring including a concave edge opening in the direction of rotation with transmission of torque between the armature disk and hub plate being transmitted through the springs with the degree of deflective elongation of the springs being determined by the torque transmitted thereby causing the central portions of the springs to straighten to increase the distance between the ends.