Innovative hydraulic drive systems save energy, cost

Author: Linda Thomas Terhune
Imagine a huge excavator and its mighty engine moving tons of dirt. Now imagine filling its fuel tank. With the rising cost of diesel fuel, it’s become a big concern for both operators and manufacturers. This is where Purdue researcher Monika Ivantysynova is making impact.

Imagine a huge excavator and its mighty engine moving tons of dirt. Now imagine filling its fuel tank. With the rising cost of diesel fuel, it’s become a big concern for both operators and manufacturers. This is where Purdue researcher Monika Ivantysynova is making impact.Ivantysynova, the Maha Fluid Power Systems Professor, with joint appointments in mechanical engineering and agricultural and biological engineering, is investigating advanced energy-saving hydraulic drive systems. Her work with displacement-controlled actuation has both environmental and economic implications, traditionally resulting in fuel savings around 25 percent. Ivantysynova’s research team, however, achieved an astounding 55 percent savings in laboratory testing of hydraulic actuators involving heavy equipment such as excavators. Little wonder she’s attracting international attention.

 

Ivantysynova’s work at the Maha Fluid Power Research Center has drawn interest from companies such as Komatsu in Japan and domestic manufacturers like Caterpillar, John Deere, and Bobcat. And the energy-efficient equipment would surely captivate their customers—heavy equipment owners and operators.
 

Much of the research falls under the umbrella of Purdue’s Engineering Research Center (ERC) for Compact and Efficient Fluid Power (directed by Ivantysynova), which was funded by a five-year, $21 million grant from the National Science Foundation in May 2006. Several ERC inventions are in the patent-application phase, a startup company is in the works, along with much inquiry about licensing.

In her research on displacement-controlled actuators, Ivantysynova’s team built a test rig to simulate a trench-digging cycle. The displacement-controlled excavator consumed 39 percent less total energy than the traditional load-sensing excavator. The efficiency improvement was almost entirely due to the elimination of valve-metering losses rather than energy recovery.

“It’s a breakthrough,” Ivantysynova says. “If this technology comes to market, people will recognize the importance of having efficient pumps and motors.”

Ivantysynova is also investigating energy savings that come from a novel approach to lubricating gap construction. The lubricating gap between the cylinder block and valve plate of swash plate type axial piston
machines is a major contributor to total machine losses, whether under partial- or maximum-load operating conditions. Ivantysynova applied a micro-structured waved surface to one of the sliding surfaces of the
cylinder block-valve plate interface and significantly reduced power loss at partial load conditions in the interface. Measurements of a pump running with the prototype valve plate showed an increase in total pump
efficiency of up to 10 percent.

Ivantysynova also hopes to see her work in energy efficiency and fuel savings passed on to average consumers through fuel-efficient hydraulic hybrid vehicles, a lighter and more compact alternative to electric hybrids that power cars such as the Toyota Prius. Her dream is to have Purdue become a major world center for such vehicles.

Hydraulic pumps help reduce energy loss and lower emissions by allowing freedom in engine management. The envisioned power-split drive represents a class of Continuously Variable Transmission (CVT) that combines the convenience of CVT with high overall transmission efficiency. In its hybrid configuration, a high-pressure accumulator captures the braking energy that is regenerated to aid the engine power during the next propulsion event. Electric hybrids cannot store brake energy. The technology could be used on both small and large scales to power passenger vehicles, along with military vehicles and semis.

Ivantysynova’s groundbreaking research has set Maha Laboratories apart from other such facilities in the world. “We are definitely the leading fluid hydraulics laboratory in the United States. Purdue has the largest laboratory,” she says.