The Impact of Peak-and-Hold and Reverse Current Driving Strategies on the Dynamic Performance of Commercial Cartridge Valves

High speed valves have an important role in many existing fluid power systems and are an enabler for many proposed digital hydraulic systems. One method commonly used to improve the dynamic performance of on-off valves involves modifying the electrical input signal to the solenoids to reduce the inductive lag and eddy current decay. This research examined two commercially available direct actuated and pilot-stage actuated cartridge poppet valves and the role of peak-and-hold voltage and reverse current input profiles on opening and closing switching times. A test stand was built to characterize the performance of these valves. The valves were placed between two high frequency pressure transducers and the pressure differential across the valves was recorded, allowing the calculation of transition and delay time. The peak and reverse voltage duration was tested over a range of zero to ten milliseconds and an optimum response was found at a peak duration of six to eight milliseconds. Peak voltages ranged from 50 to 55 volts, followed by a holding voltage of 12 volts. Reverse current profiles were used to turn off the valves with a maximum peak current of three amps. The reverse current was used to increase the decay rate of eddy currents thus improving the turning off performance of the valves. Commercial valves that had a range of 33 to 55 millisecond turn-on response without input signal modification; these same valves had response times reduced to a range of seven to nine milliseconds after applying the peak and hold method. The turn-off time was reduced from 130 milliseconds to a range of 16 to 50 milliseconds after adding reverse current inputs. This improvement in valve performance can lead to siginificant energy savings due to reduction of transition losses and can widen the useful application of the valves.