Viscous fluid torsional vibration dampening device having an elastic

Abstract

A flywheel assembly comprises a first flywheel, a second flywheel supported on the first flywheel so as to be rotatable, a drive member connected to said first flywheel to ensure a space in which viscous fluid can be contained therebetween, a driven member connected to the second flywheel to constitute, together with the first flywheel and the drive member, a fluid chamber with which viscous fluid is filled, a coil spiring for elastically connecting the members to each other, and a viscous damper part for moving viscous fluid in the fluid chamber in response to relative rotation between both the members to create viscous resistance. The driven member has a window hole containing the coil spring and a fluid supplying path connecting with the fluid chamber from the window hole. The viscous damper part has chokes for creating viscous resistance when the first flywheel and the driven member are relatively rotated. The chokes are opened and closed by sliders which can be pressed against the wall of the fluid chamber in a dry friction state. The driven member has a plurality of recesses concaved radially inward on its outer peripheral surface. The sliders respectively have projections projected into the recesses of the driven member, and the chokes are formed between the recesses and the projections.