Design and Characterization of a Five-Chamber Constant-Volume Hydraulic Actuator

This paper describes a new design for a constant-fluid-volume, also known as a symmetrical, hydraulic cylinder. In contrast to the two fluid volume chambers of a typical hydraulic cylinder, the constant-fluid-volume cylinder contains five potential fluid chambers. Relative to three and four chamber designs, both previously described in the engineering literature, the five chamber design enables a minimum-diameter solution with a simpler porting implementation. Following a general description of the five-chamber design and its motivation, a five-chamber cylinder prototype is described and presented. Experimental results are presented comparing some behavioral characteristics of the fivechamber cylinder to a double-rod cylinder, and to two variations of single-rod implementations. Finally, a minimum-diameter five-chamber cylinder variant is described, and its geometric characteristics compared to equivalent doublerod and four-chamber cylinder implementations.