In some applications, precise pressure regulation is unimportant. A few pounds per square inch one way or the other makes little difference. But in many other applications, precision is critical. There, even a slight error in pressure measurements may ruin accuracy or even cause danger.
Problem is, precisely regulating pressure is not always easy. In particular, many pressure regulators have difficulty obtaining true zero gauge pressure. For designers of laboratory equipment, ultrasound welding systems, air bags, and many other devices, that can be a problem.
To solve it, engineers from Hoerbiger-Origa have developed a pressure regulator that employs a unique technique. Known as the Tecno, the new device uses a piezoelectric "pill," which can almost instantly limit airflow in response to change in an applied low-power voltage drive signal. To accomplish that, the piezoelectric element within the pill changes shape when the desired drive voltage is applied, thus regulating pneumatic pressure in an airway.
In the field of pneumatic pressure regulation, Hoerbiger-Origa's technique represents a dramatic departure from traditional designs. In the past, most regulators employed one of two methods: a voice coil or a proportional poppet regulator. The voice coil, an electromechanical technique, was often vibration sensitive, and had difficulty achieving true zero gauge pressure. Poppet-type regulators have had better luck attaining zero gauge pressure, but typically require higher power.
In the new design, however, Hoerbiger-Origa claims that their regulator can consistently achieve zero gauge pressure without the need for higher power. What's more, it is not vibration- or position-sensitive. The key, say its engineers, is the use of the piezoelectric element. Because it uses no voice coil or solenoid coil, magnetic energy is not needed to activate it. "Magnetic energy requires electrical current, and the Tecno uses very little of that," notes L. Howard Hurley, an engineer and product manager for Hoerbiger-Origa.
During operation, the Tecno works in three stages. A control signal (0 to 10V dc or 4-20 mA) is sent to the device. A comparator measures output pressure and opens the tiny piezo-ceramic pilot valve, bringing the output pressure to the command input. The piezo-ceramic, or "pill," provides a proportional pressure signal to a larger regulator stage. As the output pressure rises and the difference between the command and output reading decreases, the "pill" is commanded electronically to follow the input signal and change the output pressure to meet it.
One of the advantages of the system is that it operates on very small power requirements. Since monitoring and actuation require so little power, and the pill requires almost no power, the unit uses less than 0.25 W of power. As a result, it can operate off 4-20 mA current. It is also vibration insensitive, and has true zero gauge pressure capability.
"Certain applications must be able to reliably reach zero gauge pressure," notes L. Howard Hurley, a product manager for Hoerbiger-Origa. "The Tecno accomplishes that."
Additional details...Contact L. Howard Hurley, Hoerbiger-Origa Corp., 100 West Lake Dr., Glendale Heights, IL 60139, 630-871-8300
- Pneumatic positioning
- Sheet tension winding
- Air bags
- Ultrasound welding