Patent ID: 7309063

Claim:
A gas-filled spring for a vehicle, said gas-filled spring operating, wherein said gas-filled spring comprises: a cylinder; and at least one piston that operates therein and divides an internal space of the cylinder into a compression chamber and an expansion chamber; a self-pumping and self-balancing arrangement designed to ensure maintenance of necessary quantities of gas as well as gas pressure settings or differential pressures in the compression chamber and the expansion chamber in order to provide optimal spring function despite any gas leakage occurring and despite temperature variations occurring inside and outside the gas-filled spring, wherein the arrangement comprises: a means for transferring gas between said compression chamber and said expansion chamber, said means for transferring gas between said compression chamber and said expansion chamber comprising at least one passage which is arranged between the compression chamber and the expansion chamber, said at least one passage being formed in a widened portion of the cylinder such that said at least one passage is open in only one predetermined position of the cylinder and the piston relative to one another, wherein, each time the piston passes said predetermined position during movement of the piston in the internal space, the at least one passage is thereby opened and permits at least one of the following: gas transfer between the compression chamber and the expansion chamber, pressure equalization in the compression chamber and the expansion chamber, and differential pressure adjustment of gas pressures in the compression chamber and the expansion chamber; a pressure source for loading the spring with gas and maintaining gas pressure in the spring; and a pressure relief mechanism for relieving air when gas pressure in the compression chamber or the expansion chamber rises over a predetermined value, and wherein, in said predetermined position, gas can be discharged via a pressure-relief valve assembly, should gas pressure have risen in one or both of the compression chamber and the expansion chamber due to an increase in temperature.