Genetic testing has grown into a multi-billion dollar industry because it offers insight into your ancestry and, potentially, your future health. Likewise, it helps to understand fluid power’s DNA.
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In a recent keynote at the 16th Scandinavian International Conference on Fluid Power, Peter Achten of INNAS offered a thought-provoking presentation, “Fluid power genes and memes.” Genes determine physical characteristics, he explained, whereas memes — often used by internet trolls, but also in marketing and journalism — are deep-rooted ideas that influence behavior. Both apply to fluid power.
“The quintessence of hydraulics is the fluid,” said Achten. Fluid transmits and controls power, can store energy, transport heat and carry debris to a filter. It lets us make robust and flexible machines with unparalleled power, force and torque density.
The characteristics of fluids also define the “genes” of hydraulic systems, he continued. We have to accept that fluids are compressible and have viscosity that can vary with temperature and pressure, and our components always exhibit some internal leakage. But what about assumptions that our systems have high power losses, are expensive and, finally, our industry is extremely conservative and lacks innovation? “These are all memes,” said Achten.
Take efficiency. Pumps and motors often run at efficiencies below 70%. And losses in pumps and motors are peanuts compared to losses in valves, which simply control by means of energy dissipation. But that doesn’t mean inefficiency is inherent to hydraulic systems and there is nothing we can do about it. “There is no physical law, such as Carnot’s law for heat engines, that tells us that we have to accept high losses,” he said.
There is no silver bullet, not just one single innovation which will suddenly make hydraulics systems efficient, he emphasized. We need a whole range of alternatives. Some promising developments include independent metering, digital-displacement pumps, and floating-cup pumps and motors that have negligible friction forces.
And valve control needs to be replaced by distributed control systems, he said. One option is electric power distribution using electrohydraulic actuators, sometimes referred to as zonal hydraulics. Another is hydraulic power distribution via common pressure rail which, in part, relies on accumulators and hydraulic transformers. Both need further development to meet market demands for accuracy and high dynamic performance. But compared to conventional valve control, losses can be reduced by nearly 90%.
Such systems can also enable modular designs, higher-volume production and enormous cost-saving potential, to negate the meme of hydraulics being pricier than comparable power-transmission systems.
But most important, said Achten, is the meme that change isn’t possible. “We have no choice, we need to design new hydraulic systems and components based on electric and hydraulic power distribution with a clear emphasis on reduced power losses, reduced costs and improved controllability. Our future lies in a dynamic, distributed control systems with more-efficient components and modules having their own individual force and position control.” This is where we should focus, he said, simply because industry demands it. “If we don’t innovate, then the market will find another way without us.”
Hydraulic systems have specific characteristics that differentiate them from mechanical and electric systems. We have to accept these and use them to our benefit, he said. If we can achieve this renaissance of fluid power technology then hydraulics, currently a niche market, has an enormous growth potential.
Learn more at www.fluidpowerworld.com/fluid-power-genes-and-memes.
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