A vibration attenuator for a rotor of an aircraft has a first ring with an eccentric weight, a coaxial second ring with an eccentric weight, and a central ring coaxial with the first and second rings and located therebetween. A first post extends from the first ring toward the central ring and is received in a first arcuate groove formed on the central ring, whereas a second post extends from the second ring toward the central ring and is received in a second groove formed on the central ring. A motor is configured for driving the central ring in rotation about the axis relative to the motor. The grooves are equal in length, and a center of the first groove is located on an opposite side from a center of the second groove. Rotation of the central ring by the motor causes rotation of the first and second rings.

A fixing structure includes a housing including a first hole, an input member including a second hole, and rotating relative to the housing, depending on input of rotational force, a torsion spring being biased so as to return, to a predetermined reference position, a position of the input member relative to the housing, and a fixing member inserted into the first hole and the second hole in a state where the input member is rotated against biasing force of the torsion spring from the reference position to a predetermined rotational position. The fixing member includes a first insertion portion including a part press-fitted into and fixed to the first hole, and a second insertion portion including a part inserted into the second hole, and fixes the input member at the predetermined rotational position.

A fixing structure includes a housing including a first hole, an input member including a second hole, and rotating relative to the housing, depending on input of rotational force, a torsion spring being biased so as to return, to a predetermined reference position, a position of the input member relative to the housing, and a fixing member inserted into the first hole and the second hole in a state where the input member is rotated against biasing force of the torsion spring from the reference position to a predetermined rotational position. The fixing member includes a first insertion portion including a part press-fitted into and fixed to the first hole, and a second insertion portion including a part inserted into the second hole, and fixes the input member at the predetermined rotational position.

The invention includes systems having a cover attached to a frame, and a transmission unit with a rotational device connected to or part of the frame. The cover is mechanically connected to the at least one rotational device. A vibration dampening unit mechanically connected to the transmission unit such that translational movement (e.g. vertical movements) of the cover causes rotational movement of the rotational device. The rotational movement is, in turn, transmitted to the vibration dampening unit via the transmission unit. Preferably, the vibration dampening unit is a passive unit and also a resistance force modulated vibration dampening unit. The invention also includes methods for dampening vibrations on a load which includes converting translational movement of a load to rotational movement in a transmission unit, the transmission magnifies the displacement and speed of the rotational movement, and then transmitting the rotational movement to a vibration dampening unit, which dissipated the vibrational energy.

The invention includes systems having a cover attached to a frame, and a transmission unit with a rotational device connected to or part of the frame. The cover is mechanically connected to the at least one rotational device. A vibration dampening unit mechanically connected to the transmission unit such that translational movement (e.g. vertical movements) of the cover causes rotational movement of the rotational device. The rotational movement is, in turn, transmitted to the vibration dampening unit via the transmission unit. Preferably, the vibration dampening unit is a passive unit and also a resistance force modulated vibration dampening unit. The invention also includes methods for dampening vibrations on a load which includes converting translational movement of a load to rotational movement in a transmission unit, the transmission magnifies the displacement and speed of the rotational movement, and then transmitting the rotational movement to a vibration dampening unit, which dissipated the vibrational energy.

A system (1) for vibration management comprises a stator (24, 45); a rotor (26) being mounted rotatably with respect to the stator (24, 45) about a rotational axis (9); one or more active devices (41A-41C) adapted to apply forces and/or moments on the rotor (26) and/or on the stator (24, 45); at least two sensors (42) for measuring vibrational parameter values with respect to two or more different positions, particularly along the rotational axis (9); and a controller (44) adapted to provide control signals to the one or more active devices (41A-41C) based on the vibrational parameter values of the at least two sensors (42) and on the respective position.

Systems and methods for damping torsional oscillations of downhole systems are described. The systems include a downhole drilling system disposed at an end of the downhole system in operative connection with a drill bit. A damping system is installed on the downhole drilling system, the damping system having at least one damper element configured to dampen at least one HFTO mode. At least one mode-shape tuning element is arranged on the drilling system. The at least one mode-shape tuning element is configured and positioned on the drilling system to modify at least one of a shape of the HFTO mode, a frequency of the HFTO mode, an excitability of the HFTO mode, and a damping efficiency of the at least one damper element.

An apparatus for damping vibrations includes an inertial mass disposed in a cavity in a rotatable downhole component, the rotatable component configured to be disposed in a borehole in a subsurface formation, such as a resource bearing formation, the inertial mass coupled to a surface of the cavity by a damping fluid and configured to move within the cavity relative to the downhole component. The apparatus also includes a damping fluid disposed in the cavity between the inertial mass and an inner surface of the cavity, where rotational acceleration of the rotatable downhole component causes shear in the damping fluid to dissipate energy from rotational acceleration of the rotatable downhole component and causing the rotational acceleration to be reduced.

A magnetically-coupled torque assist apparatus includes a movable (rotor) magnet configured to rotate about a rotor magnet axis extending through the rotor magnet, and a stationary (stator) magnet. The rotor magnet and the stator magnet have a gap therebetween. There is an equilibrium state position (ESP) of the rotor magnet where forces acting on the rotor magnet are balanced such that the rotor magnet is stationary about the rotor magnet axis. And when the rotor magnet is rotated from the equilibrium state position (ESP) to an elastically stressed state position (SSP), magnetic fields of the rotor magnet and the stator magnet generate a resultant magnetic force on the movable magnet that biases the movable magnet towards the equilibrium state position. In some embodiments, the stator and rotor magnets are configured to create a Halbach-effect magnetic field bloom, which contributes to the magnetic forces.

The invention relates to a method for actively balancing a rotor (1), comprising: providing a device with a rotor (1) that can be rotated around an axis of rotation and a mechanism (2) allocated to the rotor (1) for actively balancing, in which a magnetic fluid (7) is received in a fluid chamber (6) formed on the rotor (1), which partially fills the fluid chamber (6) and contains at least one of the following fluids: ferrofluid and magnetorheological fluid; holding the magnetic fluid (7) by means of a permanent magnetic field of a permanent magnet (5) arranged on the rotor (1) in an initial position in the fluid chamber (6); rotating the rotor (1) around the axis of rotation (3), and passing the fluid chamber (6) and permanent magnet (5) by an electrical exciter system with a fixedly arranged electromagnet (8) during the rotation of the rotor (1), wherein the permanent magnetic field of the permanent magnet (5) and an electromagnetic field of the electromagnet (8) here overlap in an activated state for active balancing purposes, so that the magnetic fluid (7) in the fluid chamber (6) performs a mass displacement proceeding from the initial position. Also created is a device with a rotor (1) and a mechanism (2) allocated to the rotor (1) for actively balancing the rotor (1).