Researchers at Siemens have developed a small but powerful piezohydraulic actuator. Although it is only about nine centimeters long, it can apply a force of more than 150 newtons - equivalent to a weight of 15 kilograms. Such actuators are used to operate valves and flaps, for example, and can also be employed in robots.
The concept combines piezomechanics with hydraulics. A voltage causes tiny deflections in a piezoelectric crystal and an internal hydraulic system combines these small movements to generate a rise of two centimeters. Purely electromagnetic actuators loose efficiency if they are very small.
Another advantage of the new actuator is its metallic enclosure, which ensures that all of the required hydraulic fluid is contained in the system so that the actuator only has to be supplied with electricity and not with fluid. Moreover, the actuator is protected against external influences such as dust, humidity, and chemicals.
Piezoelectric crystals expand in a particular direction as soon as a voltage is applied. These crystals are used to drive injection valves in combustion engines, for example. One of their advantages is their dynamic response. Due to their great stiffness, they respond with almost no lag. By contrast, a conventional hydraulic system needs to have a central pump compress the hydraulic fluid in all of the system's pipes before it can generate a mechanical motion.
The piezohydraulic actuator developed by Siemens' global research department Corporate Technology (CT) achieves a high level of stiffness because it only needs six milliliters of hydraulic fluid. The enclosed hydraulic system consists of three adjacent metallic bellows that can expand along an axis and are connected to one another by non-return valves. If the piezoelectric crystal is excited, it expands into the central chamber, where it creates pressure.
This pressure opens the valve to the adjacent chamber, which has an actuator stem attached to its front. The inflowing fluid slightly expands the bellows and the actuator stem is extended. Using a patented integration solution, the developers achieve a total rise of two centimeters:
They operate the piezoelectric crystal with a high-frequency sawtooth voltage and combine the rapid succession of small expansions to create a completely smooth motion of the actuator stem. The concept has two advantages:
If the reverse voltage waveform is applied, the pumping direction and the motion are reversed as well. In addition, the actuator maintains its extension once it has been set. By contrast, the actuators used in conventional gears to transmit power cannot withstand vibrations and other influences over the long-run.
The system is a further development of a piezohydraulic actuator that CT created for controlling the valves of large-scale combustion engines such as gas turbines. According to the developers, the new actuator might also be used for other applications such as in robots, in the operation of aircraft ailerons, and in medical and cleanroom technology.
Dr. Norbert Aschenbrenner | Siemens InnovationNews
Fraunhofer IWS Dresden collaborates with a strong research partner in Singapore
15.02.2017 | Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS
Russian researchers developed high-pressure natural gas operating turbine-generator
06.02.2017 | Peter the Great Saint-Petersburg Polytechnic University
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News