Liquid-gas constant force recoil spring

摘要

A constant-force spring of the liquid-gas type comprising a piston slidable in a cylinder and an elastomeric bladder enclosed in the cylinder. The bladder is filled with a gas, preferably nitrogen. The rest of the cylinder is filled with a compressible liquid having a low bulk modulus. A liquid that can be used is dimethyl silicone which has a bulk modulus of only 150,000 psi. The low bulk modulus gives a low spring constant which is necessary if a constant force characteristic is to be achieved.