Constant velocity elastomeric bearing joint

A constant velocity joint for joining a mast of a helicopter to a yoke for joint rotation, the mast rotating about a first axis and the yoke rotating about a second axis, the first and second axes being capable of misalignment, comprising:

• a rigid disk shaped carrier defining an axis of symmetry and having a plurality of apertures formed therethrough about the periphery thereof, each of the apertures centered on an aperture axis parallel to and spaced from the axis of symmetry, the walls of the apertures defining spherical surfaces centered on a first center along the axis of the aperture midway through the carrier;
• a plurality of elastomeric bearing assemblies, each of said elastomeric bearing assemblies being received in one of the apertures in the rigid carrier, said elastomeric bearing assemblies including:
• (a) a spherical elastomeric bearing having an outer spherical surface secured to the wall of the aperture and an inner spherical surface concentric with the outer spherical surface, the center of curvature of the spherical surfaces coincident with the first center when the spherical elastomeric bearing is undeformed;
• (b) a rigid section having an outer spherical surface concentric with and attached to the inner spherical surface on the spherical bearing and having an inner cylindrical surface;
• (c) a cylindrical elastomeric bearing having an outer cylindrical surface secured to the inner cylindrical surface of the rigid intermediate section, the cylindrical elastomeric bearing having an inner cylindrical surface centered along the aperture axis;
• a pair of plates splined for rotation with the mast and having bolts extending between the pair of plates for securing between the plates the inner cylindrical surface of the cylindrical elastomeric bearing of alternate elastomeric bearing assemblies around the circumference of the rigid carrier so that the center axis of the inner cylindrical surface is parallel to and spaced from the first axis;
• a U-shaped pillow block having a bolt extending between the yoke and a cross-bar of the pillow block for securing the inner cylindrical surface of the cylindrical elastomeric bearing of each of the other said elastomeric bearing assemblies to the yoke with the center axis of the inner cylindrical surface parallel to and spaced from the second axis, the plates, the pillow blocks, and the carrier being shaped so that the carrier does not contact the plates or the pillow blocks during misalignment between the first and second axes;
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• the cylindrical spherical elastomeric bearings being deformable axially along their center axis, radially perpendicular to their center axis, and about the center of curvature, permitting torque to be transferred from the mast to the yoke with constant velocity, the rigid carrier being oriented relative to the mast and yoke to ensure a constant velocity motion.

A constant velocity joint for jointing a mast to a yoke for joint rotation, the mast rotating about a first axis and the yoke rotating about a second axis, the first and second axes being capable of misalignment, comprising:

• a rigid carrier having a generally disk-like shape and having an axis of symmetry, said rigid carrier having at least six apertures formed therethrough centered on aperture axes parallel to the axis of symmetry and spaced uniformly about the circumference of the rigid carrier at a uniform radius from the axis of symmetry, the walls of each of the apertures forming a spherical surface centered on the aperture axis of the aperture at the midpoint through the the thickness of the carrier;
• an elastomeric bearing assembly secured in each of the apertures and including;
• (a) a spherical elastomeric bearing having a predetermined thickness and concetric with the wall of the aperture, the outer surface of the spherical elastomeric bearing being secured to the wall of the aperture;
• (b) a rigid intermediate section having an outer spherical surface secured to the inner spherical surface of the spherical elastomeric bearing and concentric with the wall of the aperture, the inner surface of the rigid intermediate section defining a cylindrical surface;
• (c) a cylindrical elastomeric bearing having an outer cylindrical surface secured to the inner cylindrical surface of the rigid intermediate section and an inner cylindrical surface;
• a pair of plates splined for rotation with the mast for securing each of the inner cylindrical surfaces of the cylindrical elastomeric bearings of at least three of the elastomeric bearing assemblies, each of said plates having at least three arms extending outwardly from the first axis to mount said at least three elastomeric bearing assemblies between said arms, the rigid carrier being supported through the elastomeric bearing assemblies between said plates about the mast;
• a plurality of U-shaped pillow blocks mounted to the yoke for securing each of the inner cylindrical surfaces of the cylindrical elastomeric bearings of the remaining elastomeric bearing assemblies to the yoke, the rigid carrier thereby being supported between the mast and yoke such that the angle of the axis of symmetry of the rigid carrier always bisects the angle of misalignment between the first and secod axes to provide a constant velocity joint, the pillow blocks and rigid carrier being shaped so that they do not contact despite misalignment between the first and second axes;
• said constant velocity joint further including a lower rigid mast flapping spring element splined for rotation with the mast below the plates and having a generally downwardly facing spherical surface centered generally on the point of intersection between the first and second axes when misaligned, and further including an upper rigid mast flapping spring element splined to the mast above the plates defining an upwardly facing spherical surface centered generally on the point of intersection between the first and second axes when misaligned and a nut for threading on the threaded end of the mast to maintain the plates and flapping spring elements on the mast;
• the yoke defining an upwardly facing spherical surface centered on the point of intersection of the first and second axes when misaligned facing the spherical surface on said lower flapping spring element and a bowl mounted to said yoke above said plates and having a downwardly facing spherical surface centered on the point of intersesction of the first and second axes when misaligned facing the spherical surface on the upper flapping spring element;
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• an upper spherically shaped elastomeric element secured between the facing surfaces of the bowl and the upper flapping spring element and a lower spherically shaped elastomeric element secured between the facing surfaces of the yoke and th elower flapping spring element to limit the misalignment between the first and second axes and transmit lift forces from the yoke to the mast.