Tuned torsional viscous dampers

Claim 1

A tuned torsional viscous damper, comprising: a flat supporting disk having a radially outwardly extending circular body and a radially inner hub portion adapted to be secured to a rotary member such as a crankshaft subject to vibrations to be damped by the damper; a ring shaped inertia mass having an inner diameter and a radially inward annular opening through said inner diameter and leading from an annular working chamber into which said body extends concentrically through said opening; a viscous damping medium in said chamber; said inertia mass comprising a pair of complementary stamped heavy gauge annular sheet metal inertia plates each of which has a radially outer axially facing annular portion in parallel shear film spaced relation to said disk body having regard to the viscosity of the viscous damping medium; means at the radially outer extremities of said radially outer annular portions maintaining an accurate spaced relation between said radially outer portions; means at said radially outer extremities securing said plates fixedly together; radially inner annular axially facing portions of substantial width of said stamped inertia plates substantially offset axially away from said disk body; annular transversely angular integral offsetting bends connecting said radially inner portions to said radially outer portions, whereby said radially inner portions define concentric annular recesses of substantially greater depth than said shear film spacing and facing toward said disk body; and elastic turning spring, spacing and sealing rings substantially filling said recesses and extending across said shear film spacing into face-to-face engagement with said disk body and thereby maintaining said shear film spaced relation between said disk body and said radially outer stamped inertia plate portions; said rings being bonded at their opposite axial faces to respectively said radially inner plate portions and to said disk body and sealing said inward opening against loss of viscous damping medium, and providing tuning spring coupling between the inertia mass and the disk.