Patent ID: 6523660
Filing Date: 2003-02-25
Classification: F16D

Abstract:
A wheel hub device for a bicycle which includes an axle extending in an axial direction, a sprocket wheel mounted coaxially around and rotatable relative to the axle, and a bicycle wheel which is mounted on said wheel hub device for rotation, said wheel hub device comprising:a hub shell adapted to be rotatably mounted on the axle, and having first and second lateral ends which are disposed opposite to each other in the axial direction, and an inner peripheral wall surface which extends in the axial direction to communicate said first and second lateral ends and which defines a through hole, said inner peripheral wall surface having a first wall portion and a second wall portion respectively proximate to said first and second lateral ends, and an intermediate wall portion which is disposed between said first and second wall portions and which defines a shoulder facing towards said second lateral end; a driving barrel adapted to be rotatably mounted on the axle and rotatable relative to said hub shell, said driving barrel including a head portion which is disposed outwardly of said first lateral end and which is adapted to be rotated with the sprocket wheel, and an externally threaded portion which is disposed opposite to said head portion in the axial direction and which extends into said through hole so as to be surrounded by said intermediate wall portion; a coupling socket disposed rotatably and movably in said through hole in the axial direction, and adapted to be rotatably mounted around the axle, said coupling socket including: an engaging end which has a friction wall surface that confronts said intermediate wall portion, and an internally threaded portion that is disposed opposite to said friction wall surface in a direction radial to the axial direction to be movable in the axial direction between a fully engaged position, where said externally threaded portion is in a full threaded engagement with said internally threaded portion as a result of a clockwise rotation of said driving barrel relative to said coupling socket, which corresponds to a forward movement of the bicycle wheel, and where said friction wall surface is frictionally engaged with said intermediate wall portion as a result of said full threaded engagement, and a partially engaged position, where said externally threaded portion is in a partial threaded engagement with said internally threaded portion as a result of a screwing-out movement of said internally threaded portion relative to said externally threaded portion, and where said friction wall surface is disengaged from said intermediate wall portion; a coupling end disposed opposite to said engaging end in the axial direction away from said driving barrel; and an abutment member disposed on and extending radially and outwardly from said coupling socket, and located between said engaging end and said coupling end so as to spacedly face and move toward said shoulder in the axial direction when said internally threaded portion is moved to the fully engaged position; a sliding member adapted to be sleeved on the axle, and movable in the axial direction; an associating spring mounted in said through hole, adapted to be disposed around the axle, and interposed between said coupling socket and said sliding member such that, during the screwing-out movement, said associating spring cooperates with said sliding member to stabilize movement of said coupling socket in the axial direction; and a coil spring adapted to be disposed around the axle, and interposed between said shoulder and said abutment member, said coil spring having a first biasing force and including a depressed end disposed to bias against movement of said abutment member towards said shoulder and against a second biasing force of said associating spring, and an abutting end disposed opposite to said depressed end in the axial direction to abut against said shoulder such that when the clockwise rotation of said driving barrel is terminated suddenly while the forward movement of the bicycle continues as a result of inertia, said internally threaded portion rotates relative to said externally threaded portion in a screwing-out movement so as to be disposed in the partially engaged position, and a frictional force is simultaneously imparted to said abutting end to enable said depressed end to drag said abutment member and said coupling end of said coupling socket to rotate relative to said associating spring while said depressed end is biasing against movement of said abutment member and against the second biasing force so as to expedite the screwing-out movement.