Rear derailleur with damping function

A rear derailleur with a damping function, comprising

• a base portion, comprising a frame engaging section and a first pivoting section that are connected to each other;
• a linkage assembly, comprising a first linkage and a second linkage, wherein an end of the first linkage and an end of the second linkage are pivotally connected to the first pivoting section, respectively;
• a movable portion, comprising a second pivoting section and a seat body that are connected to each other, wherein the other end of the first linkage and the other end of the second linkage are pivotally connected to the second pivoting section, respectively, so that the first pivoting section, the linkage assembly, and the second pivoting section form a four-bar linkage;
• the seat body has a shaft bore;
• a chain guide portion, comprising a chain guide arm and a shaft member connected to the chain guide arm, wherein a guide wheel and a tension wheel are rotatably connected to the chain guide arm, and the shaft member passes through the shaft bore;
• a resilient member, disposed between the seat body and the chain guide portion and providing a biasing force for a rotation of the chain guide portion;
• and
• a damping assembly, comprising an inner ring, an outer ring, a plurality of first damping disks, a plurality of second damping disks, and at least one one-way bearing, wherein the inner ring is located within the outer ring, and an outer surface of the inner ring is engaged with the first damping disks;
• the outer ring is fixed to the seat body, and an inner surface of the outer ring is engaged with the second damping disks;
• the first damping disks and the second damping disks are in a staggered arrangement, and a damping material is filled between the first damping disks and the second damping disks;
• the at least one one-way bearing is engaged with an inner surface of the inner ring;
• the at least one one-way bearing is sleeved on the shaft member;
• the shaft member is freely rotatable in a first direction relative to the inner ring through the at least one one-way bearing;
• wherein when the shaft member of the chain guide portion drives the first damping disks on the inner ring through the at least one one-way bearing to rotate in a second direction opposite to the first direction, the damping material provides damping for the first damping disks to rotate relative to the second damping disks.