Addressing valves with pressure ripple

Pressure ripple can be purposely used to transmit information within a hydraulic system. For example, introducing ripple at specific frequencies into a fluid line can activate a valve, eliminating electrical wires. A key element of this system is the hydraulic resonator that activates the valve when a specific frequency pressure ripple is present in the line. This paper presents a linear and nonlinear model of the hydraulic resonator with experimental validation. The hydraulic resonator consists of an inertance tube, a series capacitor, made up of a deforming elastic membrane, and an orifice. For system validation, displacement of a valve, the capacitor, and system pressure are measured. The model was effective at predicting the natural frequency of the system and the narrowness of the resonant peak. Different effects were also shown experimentally by changing the fluid's viscosity and system parameters.