Combined isolation and torsional vibration damping device

A combined isolation and torsional vibration damping device for a driven shaft that receives an input torque that varies cyclically between a peak input torque and a low input torque at a peak input torque frequency, comprising:

• a shaft adapter that is connectible to the driven shaft, wherein the shaft adapter defines an axis;
• a rotary drive member that is rotatably connected to the shaft adapter, wherein the rotary drive member has an exterior drive surface that is engageable with an external torque load so as to transmit torque to the external torque load, and wherein the rotary drive member at least partially encloses a chamber;
• at least one isolation member positioned to transfer torque between the shaft adapter and the rotary drive member, wherein the at least one isolation member has an isolation member stiffness that is selected such that a natural frequency of a system made up of the external torque load and all portions of the combined isolation and torsional vibration damping device which transmit torque from the shaft adapter to the external torque load, is lower than the peak input torque frequency;
• a torsional vibration damping structure that includes an inertia member that is entirely contained in the chamber and an elastomeric damping member positioned to elastically connect the shaft adapter and the inertia member, wherein the inertia member has an inertia, and the elastomeric damping member has a stiffness, wherein a stiffness of the elastomeric damping member and the inertia of the inertia member provide the torsional vibration damping structure with a natural frequency that is at least 50% of the natural frequency of the driven shaft;
• and
• a supplemental damping structure that is contained in the chamber, wherein the supplemental damping structure applies a supplemental damping torque to resist relative movement between the rotary drive member and the inertia member in addition to damping provided by the elastomeric damping member,
• wherein the supplemental damping torque, the inertia of the inertia member, and the stiffness of the elastomeric damping member are selected such that, during use of the driven shaft, a sum of torques applied to the shaft adapter from a plurality of torque sources including the supplemental damping torque, a torque from viscous damping within the elastomeric damping member, a torque from elastic deformation of the elastomeric damping member, and a torque from the inertia in the inertia member, opposes a torque applied to the shaft adapter from the driven shaft at a natural frequency of the driven shaft with the combined isolation and torsional vibration damping device thereon, and limits a maximum twist between a first end of the driven shaft and a second end of the driven shaft, to below a yield point of the driven shaft.