Rexroth’s electronic BODAS system solution, Diesel Hydraulic Control (DHC), features high dynamic response of the travel drive and implement hydraulics—even at reduced diesel engine speeds and for TIER 4 final engines. Developed together with the diesel engine specialists from Bosch, this solution for engine management and drive/working hydraulics reduces diesel fuel consumption by up to 20%.
The TIER 4 emissions regulations for mobile equipment that take effect in 2014 will likely result in significantly poorer load response of diesel engines. Furthermore, manufacturers of excavators, telehandlers, and other mobile work equipment are reducing the engine speeds in order to consume less diesel fuel. Current control devices cannot compensate for this sluggishness. The potential risk is lower productivity.
With DHC, Rexroth has teamed with Bosch to develop a new control strategy that retains lively response—even under conditions of diminished load response and lower engine speeds. DHC changes the traditional function sequence and lets the diesel engine know expected load requirements. This is accomplished using matched controllers from Bosch for engine management and from Rexroth for the travel drive and implement hydraulics, using a common special map. This DHC system map represents the vehicle-specific relationships between rpm, efficiency and torque.
Diesel Hydraulic Control continuously determines the demands of the travel drive and implements hydraulics and uses this information to dynamically calculate the optimal operating points for the diesel engine and hydraulic components by means of the DHC system map. In practice, the joystick for the implement hydraulics transmits pending work requirements directly to the DHC, which in turn passes this requirement to the diesel ECU. This allows the engine time to prepare for the imminent mechanical load. This compensates for the expected poorer load response of TIER 4 final diesel engines. At the same time, DHC makes it possible to operate the equipment at the accustomed dynamic response levels in spite of lower engine speeds.
Since DHC means that the diesel engine only provides as much power as the machine actually needs at any given moment, fuel consumption is reduced compared with current figures. Fuel savings of up to 20% as measured in real-life testing will reduce the total cost of ownership for operators—with no sacrifice in dynamic response of the travel drive and implement hydraulics.