Hydraulics enters the digital age
Simple on/off valves hold the potential to revolutionize hydraulics technology. New digital hydraulics is faster and more reliable than traditional valve technology. It also saves energy - and a lot of it.
Digital hydraulics was invented at the Department of Intelligent Hydraulics and Automation (IHA) of Tampere University of Technology around ten years ago. The innovation is based on simple on/off valves controlled by a computer.
"Instead of continuously controlling the size of the valve orifice, it is either open or closed as necessary. Connecting several valves in parallel allows for a large number of control options. The operation controls are carried out by a computer", says Adjunct Professor Matti Linjama who fathered the idea.
Parallel-connected valves can replace all conventional analogous servo and proportional valves. "At the moment, manufacturers have hundreds of different valves in their product range. With a digital solution one servo valve can be replaced with many small on/off valves connected in parallel."
Reliability and energy savings
Digital hydraulics is considerably faster and more reliable than traditional valve technology. Simple on/off valves are robust and tolerate even dirty media. When several such valves are connected in parallel, one damaged valve will not bring production to a standstill. Instead, the repairs can be done, for example, during the next scheduled downtime.
The research findings also demonstrate that digital hydraulics saves a surprisingly large amount of energy. "Energy usage was decreased by 30-40 percent. A conventional valve is always a compromise and compromises waste energy. Digital valves can significantly reduce energy loss, because they can be optimized according to the workload."
Research on energy efficiency is still in its early stages at TUT. According to Linjama, the latest simulation and measurement results are showing a 70-80 percent reduction in energy loss compared to traditional valve control systems. This will significantly decrease fuel consumption and vehicle emissions.
Operational controls require computational capacity
The main challenge of digital hydraulics is regulating the on/off valves. The more digital valves are connected in parallel, the more calculations are required to control them. Optimizing simultaneous performance and energy economy sets high demands for computational capacity.
However, Linjama assures that, in practice, digital hydraulics and intelligent computer controls will markedly improve machine performance and operating efficiency. Prices will also drop because of the lower production costs of on/off valves compared to fine-mechanical servo valves.
Interest from industry
Industry has also discovered the benefits of digital hydraulics. Around a dozen companies are involved in the research conducted at IHA.
"One company recently developed an analogue valve compatible with their application, but after testing digital valves decided to opt for our solution instead", says Head of Department Matti Vilenius.