Volumetric hydraulic fuse valve

Abstract

A fluid fuse is operable to shut off fluid flow only when a certain predetermined volume of fluid has passed through in a single operative cycle. This can then be reset by dropping the inlet pressure. The device protects a hydraulic system from line rupture while automatically resetting after every routine operative cycle when less than the predetermined volume flows. A cylinder has a large diameter bore portion and a small diameter bore portion and holds a sliding piston with large and small diameter segments sealed to respective bore portions by sliding seals. An annular fluid chamber between the seals is reduced in volume as the piston, during fluid flow, moves from a reset position toward a closed position. In the closed position a valve member at the end of the small diameter segment seals off fluid flow as it engages a valve seat at the outlet. Fluid from the annular chamber passes to the outlet through an axial passage in the piston so that the piston may advance. A spring forces the piston back to the reset position from a partial travel position automatically when the outlet pressure is restored at the end of a normal cycle. When rupture of a line occurs, the piston travels to the shut off position from which the spring can reset it only after the inlet pressure is removed.