How does a piezo valve...
...actually work?
HOERBIGER has been manufacturing high-precision piezo valves for demanding applications for over 30 years and is still constantly improving them. But how do these tiny switching controllers actually work? Philipp Baldermann, Head of the Flow & Motion Control Business Unit in Altenstadt, explains.
What is a piezo valve?
Philipp Baldermann — A piezo valve or “microvalve” controls the flow of gas in various applications, similar to the way heart valves regulate the flow of blood in the body. It opens and closes to control the amount of gas flowing through it. Unlike our heart valves, piezo valves can only control gases such as air, oxygen or nitrogen, but not liquids, as these would block the small channels in the valve.
And how does it function?
PB — It’s based on the piezoelectric effect, in which certain materials are deformed by electric fields. Like a sandwich, the bending transducer at the heart of the piezo valve consists of two layers of piezoceramic with a separating layer in between. When we apply a voltage, the ceramic layers expand and bend the transducer, opening or closing the valve. The movement is only 50 micrometers, about half the thickness of a human hair.
Where are piezo valves used?
PB — Wherever maximum speed, maximum accuracy and minimum power consumption are required. Examples include ventilators for premature babies, pneumatic scalpels for eye operations, and measuring leakage for electronic devices. After 30 years on the market we are still finding new applications, such as cleaning microprocessors in chip production.
What’s the advantage over mechanical or solenoid valves?
PB — Mechanical valves require additional motors, which is not possible in the micro and precision range. Solenoid valves, on the other hand, consume a lot of energy to power the magnetic coil, so the valves heat up. That makes them unsuitable for heat-sensitive applications such as ventilation or leakage measurement. Solenoid valves can be either fast or accurate, but not both at the same time.
HOERBIGER piezo valves are both fast and accurate, and consume very little energy. The energy in a strawberry (around 21,000 joules) is enough to switch the valve 1 billion times. That low energy consumption means they can also be used in potentially explosive atmospheres.
The energy in a strawberry is enough to switch a piezo valve a billion times.