Diesel engine performance has been tuned to the point where there’s not much more engineers can do to squeeze out any further fuel efficiency.
So in the race to improve gallons per hour, manufacturers have turned to the hydraulics and other systems, and Bosch Rexroth is well positioned to play a leading role in next era of diesel energy efficiency.
At Bauma today the company unveiled a new electrohydraulic pump control system which it calls “virtual bleed off” technology, or VBO. Bernd Schunk, senior vice president sales, mobile applications, says the new pump control system pumps only the amount of oil needed and combines lower fuel consumption with fast response times and dynamic system stability.
Doosan has also partnered with Bosch Rexroth as a technical partner to develop its D-Ecopower technology based on VBO. The company is displaying its DX340LC-3 and DX380LC-3 excavators with D-Ecopower and claims it consumes 12 percent less fuel than comparable models without.
Another Bosch Rexroth innovation is its hydraulic start/stop solution. This technology is used in passenger vehicles—and now for the first time in heavy equipment on the Atlas Weyhausen AR 60 wheel loader shown at Bauma. The start/stop system uses variable valve pumps and accumulators to store and release energy to hydrostatic drives and hybrid systems.
The energy storage systems are particularly good at reducing fuel consumption in machines or applications with high idle times, Schunk says. If no energy is required for the machine’s driving or working functions, the engine automatically shuts off if it has stored enough energy for a hydraulic restart. The start/stop system’s hydraulic flywheel operates in the open circuit and builds up the required power boost not only for restarts but when extra power is needed for heavy loading as well.
“The heightened use of electronics in construction machinery makes it possible to orchestrate the complex interplay of a machine’s systems—its diesel engine and implement hydraulics, exhaust gas aftertreatment and ventilations systems—in such a manner that new emission standards can be met,” Schunk says. “At the same time the machine’s functionality is maintained or even improved.”
There’s no D2 in the name, but the R2 hydromechanical variable transmission from the Dana Rexroth joint venture promises to send machine fuel efficiency soaring to new intergalatic heights.
Initial tests with the group’s HVTs have demonstrated fuel savings of up to 25 percent compared to comparable machines with torque converters. The R2, debuted today at Bauma, is a modular platform with a full suite of configurable options.
Software controls enable direct or remote mounting , flexibility in shift control and drive strategy parameters and the deployment of up to three PTOs (power take offs).
The R2 system is designed to maximize efficiency and reduce machine ownership and operating costs, particularly for frond-end loaders, motor graders, industrial lift trucks, forestry skidders and other off-highway applications requiring 180 to 260 horsepower.
“The R2 is unique in its ability to integrate hydrostatic, mechanical and control systems through a modular approach that can accommodate the application requirements and customer preferences demanded by the offf-highway market,” said Jeroen Decleer, managing director of Dana Rexroth Transmission Systems.