Provided are a volume change compensation device capable of reducing a manufacturing burden with a simple configuration and a damper device including the volume change compensation device. A damper device 100 includes a rotary damper, and includes a volume change compensation device 140 in a shaft 121 of a rotor 120. The volume change compensation device 140 includes an inner cylinder piston 142 pressed by an inner cylinder piston pressing elastic body 145 in a body tube 141 communicating with a hydraulic fluid housing portion 103 of the damper device 100 through a connection path 141a. The inner cylinder piston 142 is formed in a bottomed cylindrical shape opening on a connection path 141a side. In the inner cylinder piston 142, an inner cylinder inner small piston 143 is pressed against a bottom portion 142b by a small piston pressing elastic body 144. An air hole 142c is formed at the bottom portion 142b of the inner cylinder piston 142. The inner cylinder inner small piston 143 slides in the inner cylinder piston 142 according to the amount of hydraulic fluid 150 in the inner cylinder piston 142.

A rotation damper has a housing, a magnetic field source and a damper shaft designed as a hollow shaft, and a coupling rod arranged inside the damper shaft. The hollow shaft and the coupling rod form interacting transmission units and convert a relative axial movement of the coupling rod into a rotational movement of the hollow shaft. A displacer unit is arranged in the housing. The displacer unit includes the damper shaft and meshing displacer components that are rotatable in relation to each other. The displacer unit contains a magnetorheological fluid as the working fluid and can be operated thereby. The magnetic field source is configured for applying a magnetic field to the displacer components in order to dampen a rotational movement of the damper shaft.

The fluid damper device (10) has the rotor (30) which is inserted to the bottomed cylindrical case (20) and the cover (60) which is fixed to the opening portion (29) of the case (20). The welding protrusions (80) which are to be welded to the cover (60) are formed on the inside circumferential surface of the case (20) and spaced out in the circumferential direction. On the other side (L2) in the axial (L) direction of the welding range (X), within which the welding protrusions (80) and the cover are welded together, the first outflow prevention portion (91L, 91R) is formed. On the other side (L2) of the first outflow prevention portion (91L, 91R) in the axial (L) direction, the arc-shaped step surface (76) which functions as the outflow regulation portion (95) is provided to regulate the resin protruded and prevented it from reaching the position of the R-ring (49).

A damping mechanism includes a chamber, a movable blocking member and a power assembly. At least part of the movable blocking member is located in the chamber and cooperates with an inner wall face of the chamber to encloses a damping fluid cavity; at least one of the chamber and the movable blocking member defines a damping fluid circulation port in communication with the damping fluid cavity; and the power assembly is abutted against the movable blocking member, and configured to drive the movable blocking member to move relative to the chamber to change volume of the damping fluid cavity.

A rotary damper having a simple self-standing mechanism which does not cause an inconvenience such as bounce of an opening/closing member at an end of an opening operation of the opening/closing member such as toilet lid is provided. A rotary damper has a housing, a shaft, a vane, a sliding member, an O ring, and a cap as main components. A shaft portion, formed in a pressure chamber of the housing, includes a blade portion protruding in an axial direction of the shaft portion. A cutout portion is formed in a center portion between both ends of the blade portion. On another side surface of the blade portion, a first groove is formed in a circumferential direction from a base of the blade portion to the outer periphery of the shaft portion. A second groove is formed on the outer periphery of the shaft portion spaced from the first groove.

A rotary damper has a housing and a damper shaft rotatable in the housing. A damper volume contains magnetorheological fluid for influencing the damping of a damper shaft rotation relative to the housing. A partition wall on the shaft and a partition wall formed on the housing divide the damper volume into two variable chambers. A gap is formed between the partition unit of the housing and the damper shaft, and a gap is formed between the partition unit on the damper shaft and the housing. The magnetic field source includes a controllable electric coil for influencing the strength of the magnetic field and thus the strength of damping. A substantial part of the magnetic field of the magnetic field source passes through at least two of the gaps and influences the two gap sections in dependence on the strength of the magnetic field.

A chassis component has a rotary damper with a housing, a damper shaft rotatably accommodated thereat, a displacing device in the housing, and a magnetic field source. The displacing device has a damper volume with magnetorheological fluid to influence the damping of the rotary motion of the damper shaft relative to the housing. The damper volume is divided into variable chambers by a partition wall connected with the housing and a partition wall connected with the damper shaft. Radial and axial gaps are formed between the partition walls, the damper shaft and the housing. The magnetic field source has a controllable electric coil for influencing the strength of the magnetic field and thus the strength of damping. A substantial part of the magnetic field of the magnetic field source passes through the gaps and influences the gap sections in dependence on the strength of the magnetic field.

A rotary damper (1) has a first sealing ring (8a) and a first bushing (4a) which are located between a through-hole (23) of a circular cylindrical chamber (21) inside a case (2) and a lower end part (33a) of a rotor body (31) of a rotor (3), and a second sealing ring (8b) and a second bushing (4b) which are located between a through-hole (60) in a lid (6) and an upper end part (33b) of the rotor body (31). The first sealing ring (8a) has an outer peripheral surface (85) having a width in a direction of a center axis of the circular cylindrical chamber (21) and being pressed against an inner peripheral surface (220) of the through-hole (23), and an inner peripheral surface (84) having a width in the direction of the center axis of the circular cylindrical chamber (21) and being pressed against an outer peripheral surface (34) of the lower end part (33a), and the second sealing ring (8b) has an outer peripheral surface (85) having a width in the direction of the center axis of the circular cylindrical chamber (21) and being pressed against an inner peripheral surface (64) of the through-hole 961 (60), and an inner peripheral surface (84) having a width in the direction of the center axis of the circular cylindrical chamber (21) and being pressed against the outer peripheral surface (34) of the upper end part (33b).

A rotary damper (1) has a first sealing ring (8a) and a first bushing (4a) which are located between a through-hole (23) of a circular cylindrical chamber (21) inside a case (2) and a lower end part (33a) of a rotor body (31) of a rotor (3), and a second sealing ring (8b) and a second bushing (4b) which are located between a through-hole (60) in a lid (6) and an upper end part (33b) of the rotor body (31). The first sealing ring (8a) has an outer peripheral surface (85) having a width in a direction of a center axis of the circular cylindrical chamber (21) and being pressed against an inner peripheral surface (220) of the through-hole (23), and an inner peripheral surface (84) having a width in the direction of the center axis of the circular cylindrical chamber (21) and being pressed against an outer peripheral surface (34) of the lower end part (33a), and the second sealing ring (8b) has an outer peripheral surface (85) having a width in the direction of the center axis of the circular cylindrical chamber (21) and being pressed against an inner peripheral surface (64) of the through-hole 961 (60), and an inner peripheral surface (84) having a width in the direction of the center axis of the circular cylindrical chamber (21) and being pressed against the outer peripheral surface (34) of the upper end part (33b).

Provided are a seal body capable of ensuring a high liquid tightness even upon operation of a rotor and a rotary damper including the seal bodies. A rotary damper 100 includes a housing 101. The housing 101 includes a rotor 130 in a housing body 102, and is closed with a lid 120. An inner chamber 103 of the housing body 102 is divided into four cells by fixed vanes 104, 105 and movable vanes 136, 137 provided at the rotor 130. The fixed vanes 104, 105 and the movable vanes 136, 137 include, at tip end portions thereof, fixed vane seal bodies 110 and movable vane seal bodies 140. At each of the fixed vane seal bodies 110 and the movable vane seal bodies 140, a cavity formation groove 112a, 112b, 142a, 142b and fluid guide grooves 114, 144 are formed at each side surface 111a, 111b, 141a, 141b.