Passive damper

A passive damper for providing damping of a first item relative to a second item, the damper comprising:

• a cylinder that is arranged to be operatively connected to a first item, the cylinder having a longitudinal direction and comprising a first chamber, a second chamber, and a third chamber;
• a piston arrangement that is arranged to be operatively connected to a second item, the piston arrangement comprising a first piston coupled to a second piston to move with the second piston, wherein the first and second pistons are movable in the longitudinal direction in the cylinder, the pistons configured such that each piston can move between two chambers;
• a first fluid passage that is configured to allow fluid flow from one side of the first piston to an opposing side of the first piston, a second fluid passage that is configured to allow fluid flow from one side of the second piston to an opposing side of the second piston, and one-way valves associated with the fluid passages;
• and
• damping fluid in the cylinder;
• wherein one of the one-way valves is configured so that the damping fluid is restricted from flowing through its associated fluid passage in a first direction of movement of the piston arrangement in the cylinder and the other of the one-way valves is configured so that the damping fluid is restricted from flowing through its associated fluid passage in a second direction of movement of the piston arrangement in the cylinder;
• and
• wherein the pistons and chambers are configured so that damping fluid relatively freely flows around the respective piston when the piston is in one chamber and the damping fluid is restricted from flowing around the respective piston when the piston is in another chamber.

A passive damper for providing damping of a first item relative to a second item, the damper comprising:

• a cylinder that is arranged to be operatively connected to a first item, the cylinder having a first chamber, a second chamber, and a third chamber;
• a first piston coupled to a second piston to move with the second piston, the first and second pistons arranged to be operatively connected to a second item, the pistons being movable in the cylinder;
• a first fluid passage that is configured to allow fluid flow from one side of the first piston to an opposite side of the first piston, the first fluid passage associated with a one-way valve;
• a second fluid passage that is configured to allow fluid flow from one side of the second piston to an opposite side of the second piston, the second fluid passage associated with a one-way valve;
• and damping fluid in the cylinder;
• wherein the damper is configured so that damping occurs in two diagonally opposite quadrants of a force-displacement hysteresis loop and less damping occurs in the other two quadrants of the hysteresis loop, or so that damping occurs in two diagonally opposite quadrants of the hysteresis loop and in a portion of each of the adjacent quadrants of the hysteresis loop and less damping occurs in a remainder of each of the adjacent quadrants of the hysteresis loop.

A passive damper for providing damping of a first item relative to a second item, the damper comprising:

• a cylinder that is arranged to be operatively connected to a first item, the cylinder having a longitudinal direction and comprising a first end chamber, a middle chamber, and a second end chamber;
• a piston arrangement that is arranged to be operatively connected to a second item, the piston arrangement comprising a first piston coupled to a second piston to move with the second piston, wherein the first and second pistons are movable in the longitudinal direction in the cylinder, the pistons configured such that each piston can move between two of the chambers, each piston having a fluid passage and an associated one-way valve, wherein the one-way valve of one piston is configured to restrict fluid flow through the respective passage in an opposite direction of movement of the piston arrangement in the cylinder than the one-way valve of the other piston;
• and either the middle chamber has a perimeter gap around the pistons allowing relatively free or substantially free flow of damping fluid around the pistons when in the middle chamber, and the first and second end chambers have substantially no perimeter gap allowing little or no flow of damping fluid around the pistons when in those end chambers, or the middle chamber has substantially no perimeter gap around the pistons allowing little or no flow of damping fluid around the pistons when in the middle chamber, and the first and second end chambers have a perimeter gap around the pistons allowing relatively free or substantially free flow of damping fluid around the pistons when in those end chambers;
• and
• damping fluid in the cylinder;
• wherein one of the one-way valves is configured so that the damping fluid is restricted from flowing through its associated fluid passage in a first direction of movement of the piston arrangement in the cylinder and the other of the one-way valves is configured so that the damping fluid is restricted from flowing through its associated fluid passage in the second direction of movement of the piston arrangement in the cylinder;
• and
• wherein the pistons and chambers are configured so that damping fluid relatively freely or substantially freely flows via the perimeter gap around the respective piston when the piston is in the chamber having a perimeter gap and little or no damping fluid flows around the respective piston when the piston is the chamber having substantially no perimeter gap.