Front fork position-dependent damping for bicycles and motorcycles

A damper for a telescopic fork leg for a front fork of a vehicle comprising:

• a twin-tube cylinder including an inner tube and an outer tube defining a chamber between the inner tube and the outer tube,
• a piston rod assembly including a piston rod having an inner end portion inside the cylinder and an outer end portion outside the cylinder,
• wherein the piston rod assembly is movable within the cylinder back and forth between a compressed position and an extended position,
• wherein a first piston is attached to the inner end portion of the piston rod,
• wherein the first piston is provided with at least one first fluid channel through the first piston and a valve assembly configured to control fluid flow through the first fluid channel,
• a second piston is attached to the piston rod between the first piston and the outer end portion of the piston rod such that the first piston and the second piston are spaced apart together defining an intermediate volume inside the cylinder between the first piston and the second piston,
• wherein the first piston separates the intermediate volume from an inner volume inside the inner tube,
• wherein the second piston separates the intermediate volume from an outer volume inside the inner tube,
• wherein the inner tube is provided with at least one outlet hole through the wall of the inner tube, said outlet hole being positioned such that a sealing portion of the second piston is movable past the at least one outlet hole at compression of the damper,
• wherein the inner tube is provided with at least one return hole through the wall of the inner tube, said at least one return hole being positioned such that it connects the chamber of the twin-tube cylinder to the outer volume, and
• wherein the second piston is frustoconical with an inner narrower portion sealingly engaging the piston rod and the outer wider sealing portion sealingly engaging the inner tube, wherein the second piston comprises a second fluid channel connecting the intermediate volume and the outer volume,
• wherein the piston rod assembly comprises a valve body attached to the piston rod on the outer volume-side of the second piston, and
• wherein the valve body and the second piston are movable relative to each other along the piston rod such that the valve body is positionable in a restricting position relative to the second piston, in which restricting position the valve body is seated on an inner circumferential portion of the second piston for mitigating fluid flow through the second fluid channel, and such that the valve body is positionable in an open position relative to the second piston in which open position the valve body does not mitigate fluid flow through the second fluid channel.

A damper for a telescopic fork leg for a front fork of a vehicle comprising:

• a twin-tube cylinder including an inner tube and an outer tube defining a chamber between the inner tube and the outer tube,
• a piston rod assembly including a piston rod having an inner end portion inside the cylinder and an outer end portion outside the cylinder,
• wherein the piston rod assembly is movable within the cylinder back and forth between a compressed position and an extended position,
• wherein a first piston is attached to the inner end portion of the piston rod,
• wherein the first piston is provided with at least one first fluid channel through the first piston and a valve assembly configured to control fluid flow through the first fluid channel,
• a second piston is attached to the piston rod between the first piston and the outer end portion of the piston rod such that the first piston and the second piston are spaced apart together defining an intermediate volume inside the cylinder between the first piston and the second piston,
• wherein the first piston separates the intermediate volume from an inner volume inside the inner tube,
• wherein the second piston separates the intermediate volume from an outer volume inside the inner tube,
• wherein the inner tube is provided with at least one outlet hole through the wall of the inner tube, said outlet hole being positioned such that a sealing portion of the second piston is movable past the at least one outlet hole at compression of the damper, and
• wherein the inner tube is provided with at least one return hole through the wall of the inner tube, said at least one return hole being positioned such that it connects the chamber of the twin-tube cylinder to the outer volume,
• wherein the second piston is movably attached to the piston rod for movement back and forth along the piston rod through a first operational range relative to the piston rod,
• wherein the first operational range is such that at compression of the damper the second piston is movable towards and together with the valve body for bringing the valve body into the restricting position, and
• wherein the first operational range is such that at extension of the damper the second piston is moveable away from the valve body for bringing the valve body to the open position.