A rotary device includes a first rotor, a centrifugal element, a first urging member, and a second urging member. The first rotor includes a guide surface and is disposed to be rotatable. The centrifugal element is attached to the first rotor. The centrifugal element is radially movable along the guide surface by a centrifugal force acting thereon in rotation of the first rotor. The first urging member is configured to urge the centrifugal element. The second urging member is configured to urge the centrifugal element in a direction opposite to a direction of urging by the first urging member. The first and second urging members are further configured to rotate the centrifugal element toward the guide surface.

A torque fluctuation inhibiting device includes a mass body, first and second centrifugal elements, and first and second cam mechanisms. The mass body is rotatable with a rotor and is also rotatable relatively to the rotor. Each of the first and second centrifugal elements receives a centrifugal force to be generated by rotation of the rotor and the mass body. When a relative displacement is produced between the rotor and the mass body in a rotational direction, the first cam mechanism converts the centrifugal force that acts on the first centrifugal element into a first circumferential force directed to reduce the relative displacement. When the relative displacement is produced between the rotor and the mass body in the rotational direction, the second cam mechanism converts the centrifugal force that acts on the second centrifugal element into a second circumferential force directed to reduce the relative displacement.

A torque fluctuation inhibiting device includes a mass body, a centrifugal element and a cam mechanism. The mass body is disposed to be rotatable with a rotor and be rotatable relatively to the rotor. The centrifugal element is disposed to receive a centrifugal force to be generated by rotation of the rotor and the mass body. When a relative displacement is produced between the rotor and the mass body in a rotational direction, the cam mechanism converts the centrifugal force that acts on the centrifugal element into a circumferential force directed to reduce the relative displacement. Additionally, when the torque fluctuations inputted to the rotor have a predetermined magnitude or greater, the cam mechanism makes the mass body freely rotate with respect to the rotor.

A torque fluctuation inhibiting device inhibits torque fluctuations in a rotor to which a torque is inputted. The torque fluctuation inhibiting device includes a mass body, a centrifugal element and a cam mechanism. The mass body is disposed to be rotatable with a rotor and be rotatable relatively to the rotor. The centrifugal element is disposed to receive a centrifugal force to be generated by rotation of the rotor and the mass body. The cam mechanism converts the centrifugal force acting on the centrifugal element into a circumferential force when a relative displacement is produced between the rotor and the mass body in a rotational direction. The circumferential force is directed to reduce the relative displacement.

According to one embodiment, a damper device includes a rotator, a first oscillator, a second oscillator, and two rollers, for example. The rotator is provided with a first opening. The second oscillator includes two guide surfaces recessed in a direction closer to a first center of rotation and a transmitting part capable of moving along the first opening. The two rollers each include a ring supported by the first oscillator and a shaft extending along a second center of rotation inside the ring and rotatably supported by the ring. The shaft comes into contact with a corresponding one of the two guide surfaces of the second oscillator pushed outward in the radial direction by centrifugal force, rolls along the corresponding one of the two guide surfaces by oscillation of the first oscillator, and is pushed by the corresponding one of the two guide surfaces in the circumferential direction.

A torsional vibration damper includes an input part for introducing a torque, two intermediate elements, an energy storage element designed as a compression spring that acts on the intermediate elements, an output part for discharging a vibration-damped torque, and an elastic or resilient compensation part provided between the output part and the intermediate elements. The intermediate elements are designed as pendulum rockers and are movement-coupled to the input part. Each of the intermediate elements can move towards and away from the other in a linear motion. The output part is movement-coupled to the intermediate elements and rotatable relative to the intermediate elements. The compensation part is for eliminating play of the intermediate elements relative to the output part in an axial direction.

In a vibration damping device 20, the moment of inertia J.sub.1 of a driven member 15, the moment of inertia J.sub.2 of an inertial mass body 23, the mass m of crank members 22, the distance L3 between the center of gravity G of the crank member 22 and the fulcrum of swinging of the crank member 22 with respect to the inertial mass body 23, and the distance L4 between this fulcrum and the center of rotation RC are determined so that torque fluctuation of an object for which vibration is to be damped, which is derived based on angular displacement and angles obtained by solving an equation of motion for the driven member 15 and an equation of motion for the entire vibration damping device 20 is equal to a target value.

A damper device according to one embodiment, for example, includes: a rotating member that is rotatable about a rotational axis, the rotating member including a base portion that is plate-like and support portions that is attached to the base portion and extends in an axial direction of the rotational center; and a plurality of weight members disposed partially overlapping each other in the axial direction, the weight members being provided with tracks in respective overlapped parts of the weight members, the tracks guiding the support portion to be swingable with respect to the rotating member, wherein the support portion is shared in the tracks provided in the weight members.

A power transmission device includes an input-side rotary part to which a torque is inputted from an engine, an output-side rotary part, and a damper part. The output-side rotary part includes a first rotor and a second rotor. The first rotor is configured to be rotatable relative to the input-side rotary part. The second rotor is configured to be unitarily rotatable with the first rotor. The second rotor is configured to be rotatable relative to the first rotor when the torque fluctuates with a predetermined magnitude or greater. The damper part is configured to elastically couple the input-side rotary part and the output-side rotary part.

A coupling arrangement is provided with a vibration reduction device and with a clutch device. The vibration reduction device has at least one torsional vibration damper, an input connected to a drive, and an output connected to the clutch device by which a connection between the vibration reduction device and a driven end is at least substantially produced in a first operating state, and this connection is at least substantially cancelled in a second operating state. The vibration reduction device has a mass damper system that cooperates with the torsional vibration damper and is connected to the output of the vibration reduction device.