Piezoelectric actuators for screw-in cartridge valves

Research has been undertaken to explore the possibility of using smart materials for the actuation of screw-in cartridge valves. Four types were considered and a piezoelectric (PZT) stack was selected as the most appropriate actuator. The concept of a spool valve piloted by a PZT valve was chosen for investigation. A mathematical model of a hydraulic system with a spool valve piloted by a PZT valve is developed and the results obtained from simulation studies are assessed. Experimental tests were undertaken using a prototype PZT valve. The test results obtained confirm that the PZT valve was able to switch a high flow spool valve and the results show similar trends to those obtained from the simulations. Although effective, the current cost of the PZT valve is much higher than that of a conventional solenoid valve that it may one day replace. There are also issues to be addressed that relate top temperature dependence of the PZT valve operation. A solution is given to improve the response of the spool.