Researchers at Siemens have developed a small but powerful piezo-hydraulic actuator. Although it is only about nine centimetres 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 centimetres. Purely electromagnetic actuators lose 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 to 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 millilitres 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 centimetres. 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 is claimed to have two main 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 clean room technology.
Reinventing the wheel
Editor's Choice Electrical switching & drive systems & components
Once a curiosity in the early automotive age, in-wheel motors are now re-emerging with real promise. From electric cars to commercial vehicles and even aircraft, they are on the verge of transforming transportation engineering.
Read more...Redefining motion control with Festo’s vision for seamless and intelligent automation Festo
Editor's Choice Electrical switching & drive systems & components
The quest for precision, flexibility and efficiency continues to shape the future of industrial automation, and Festo, as a long-standing leader in automation technology, stands firmly at the forefront of this movement, driving innovation and setting the benchmark for excellence.
Read more...The opportunity and impact of MEPS electric motor regulations WEG Africa
Editor's Choice Electrical switching & drive systems & components
South African companies are gearing up for the new Minimum Energy Performance Standards, part of a global trend towards energy-efficient electric motors.
Read more...Swiss watchmaking meets hypercar power Horne Technologies
Editor's Choice
The display of Bugatti’s upcoming luxury model, Tourbillon will be something truly special. Instead of a digital version, the driver will see a genuine Swiss timepiece behind the steering wheel.
Read more...Planetary gear units for high torque requirements SEW-EURODRIVE
Editor's Choice Electrical switching & drive systems & components
[Sponsored]Packing a compact design, along with high torque and low-speed outputs, the new SEW PPK and SEW P2.e planetary gear units from SEW-EURODRIVE offer new capabilities in continuous heavy-duty applications where space is at a premium.
Read more...Servicing the electric motor sector
Editor's Choice Electrical switching & drive systems & components
Hexagon Electrical has expanded its manufacturing and service capabilities to meet the growing demand for customised, high-performance specialised electric motors in heavy engineering, and hazardous industrial and mining applications.
Read more...PC-based control for a food capsule and pod packaging machine Beckhoff Automation
Editor's Choice Electrical switching & drive systems & components
For TME, a machine builder specialising in the packaging of powdered foods, Beckhoff’s PC-based control technology offers unlimited opportunities when it comes to performance and innovative capacity in terms of flexibility, scalability and openness.
Read more...Siemens and Oracle Red Bull Racing celebrate 20 years of innovation Siemens South Africa
News & events
Siemens Digital Industries Software is celebrating the 20th anniversary of its collaboration with Oracle Red Bull Racing, representing one of the longest standing technical partnerships in Formula 1 today.
Read more...Powering southern Africa’s industrial evolution for over five decades
Editor's Choice Hydraulic systems & components
Established in 1974, Oilpower is a recognised name in South Africa’s hydraulic and pneumatic sector. What started as a small, family-run business has matured into a highly structured operation with specialised teams, experienced engineers and a reputation for technical excellence and reliability. Oilpower is celebrating its 50th anniversary this year.
Read more...Planar motor system for quality assurance Beckhoff Automation
Editor's Choice Electrical switching & drive systems & components
Achieving the shortest possible inspection times, even when working with different components, is paramount when it comes to series production. This is precisely what special machine builder, stoba Sondermaschinen set out to achieve with its InspectorONE optical inspection system, which is based on deep learning and features the Beckhoff XPlanar planar motor system at the conveyor system core.
While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.
printer friendly version