Certain ceramics have piezoelectric properties, which means that when these ceramics are mechanically deformed, voltage is created in the material. This effect also occurs in the opposite direction: applying voltage to these ceramics leads to their deformation.
This piezoelectric behaviour can be used in many applications, for instance to generate or detect ultrasonic waves, as an ignition source (spark) for lighters or propane grills, or for precision movements of optical lenses for autofocus in smartphone cameras.
Piezo technology also offers a new way of developing valves to control the pressure or flow rate of gases. When voltage is applied to the piezo bender, it bends and lifts away from the valve seat. The higher the voltage, the more the actuator bends and the more the gas can flow through the valve.
Function of the bending actuator in piezo valves
Piezo ceramics act like a small capacitor, with the applied voltage charging the ceramic material and thus bending it. To regain its original shape, the material must be actively discharged. Piezoceramics do not require energy to maintain an existing mechanical deformation. Even after a power failure, the valve retains its current position.
Therefore energy is only required if the shape of the piezo bender has to be changed, i.e. the charge of the bender itself has to be changed. The amount of energy required in this case is very small (in the order of 1 mWs), as piezoceramics have a small capacitance (between 20 nF and 40 nF). Solenoid valves, on the other hand, require a continuous energy supply of several watts to maintain the open state, with the solenoid valve also heating up in the process.
Thanks to its low energy consumption, piezo technology is ideal for battery-powered devices (which consume much less power than solenoid valves) and for applications where the valves must not heat the gas.
Fully automatic production of piezo valves (1:32 min.)