Abstract

A fluid-driven linear actuator comprises a piston configured for reciprocating motion in a piston chamber and a spool valve in a valve chamber. The valve chamber is fluidly connected to a fluid input and to a fluid output. The spool valve is configured to be hydraulically moved within the valve chamber between a plurality of spool valve configurations, comprising a first spool valve configuration wherein the valve chamber is fluidly connected to the piston chamber to thereby create a first fluid pressure differential which tends to force the piston in a first axial direction and a second spool valve configuration wherein the valve chamber is fluidly connected to the piston chamber to thereby create a second fluid pressure differential which tends to force the piston in a second axial direction. The actuator also comprises at least one switch valve configured to be switched between a plurality of switch valve configurations and to thereby create one or more differential pressure configurations which hydraulically move the spool valve.

IPC Classes  ?

• F01L 25/02 - Drive, or adjustment during operation, of distribution or expansion valves by non-mechanical means by fluid means
• F04B 49/22 - Control of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for in, or of interest apart from, groups by means of valves
• F01L 25/06 - Arrangements with main and auxiliary valves, at least one of them being fluid-driven
• F15B 15/20 - Other details