Built-in damper type front fork
A both-side rod type damper ( 11 ) is arranged in a storage chamber ( 40 ) formed inside an inner tube ( 2 ) and an outer tube ( 3 ), rods ( 31 ) and ( 32 ) of the damper ( 11 ) are coupled so as to move by the same quantity in accordance with the extending or retracting operation of a front fork, a bearing ( 5 ) for slidably supporting the rod ( 32 ) is provided at a cylinder end, the bearing ( 5 ) is movable by a predetermined quantity in a radius direction and an axial direction of the rod relative to the cylinder, and the bearing ( 5 ) moves toward the inside of the cylinder to communicate the oil chamber R 2 with the storage chamber ( 40 ) when the pressure of the storage chamber ( 40 ) is higher than the pressure of the oil chamber R 2 in the damper ( 11 ), and the communication is shut down when the movement is made to the opposite side thereof.
1. A front fork, comprising:
an outer tube;
an inner tube slidably inserted into the outer tube;
a storage chamber formed inside the inner tube and the outer tube;
a damper arranged in the storage chamber and including:
a cylinder having an air vent path formed in an upper part thereof, the cylinder further having a first and a second end;
a piston which slides in the cylinder;
an upper and a lower oil chamber defined inside the cylinder by the piston, the upper oil chamber being in fluid communication with the storage chamber via the air vent path; and
a pair of rods which are coupled with the piston and are respectively protruded from the first and second ends of the cylinder, the rods displacing by the same quantity in accordance with an extending or retracting operation of the front fork; and
a bearing provided at the second end of the cylinder and accommodated inside a flange extending toward an internal circumference from the second end of the cylinder and inside a diameter enlarged portion having a step provided on the internal circumference of the second end of the cylinder, the bearing slidably supporting at least one of the rods protruding from the second end of the cylinder,
the bearing having opposing first and second sides, a tubular bush member which slides in contact with an external circumference of the rod, a tubular valve body for retaining the bush member on an internal circumference thereof, a oath provided through the bearing in the valve body to penetrate through the valve body in the axial direction of the rod; and an elastic member interposed on the external circumference of the valve body and contacting the internal circumference of the diameter enlarged portion,
the bearing moving by a predetermined quantity in a radius direction and an axial direction of the rod relative to the cylinder, the bearing moving in the axial direction toward an inside of the cylinder to open the path through the bearing to allow the lower oil chamber and the storage chamber to be in fluid communication when the pressure of the storage chamber facing the first side of the bearing is higher than the pressure of the lower oil chamber facing the second side of the bearing, and the bearing closing the path through the bearing when the bearing is not moved in the axial direction toward the inside of the cylinder,
wherein a first gap is formed between the external circumference of the bearing and the internal circumference of the diameter enlarged portion, and a second gap is formed between an upper end of the bearing and the step, and
the bearing moves away from the flange to communicate the lower oil chamber with the storage chamber when the pressure of the lower oil chamber in the cylinder is lower than the pressure of the storage chamber outside the cylinder, and is seated on the flange to shut down the communication through the valve when the pressure of the lower oil chamber is higher than the pressure of the storage chamber.
2. The front fork according to claim 1 , wherein the first end of the cylinder is an upper end of the cylinder, and the second end of the cylinder is a lower end of the cylinder.