Bosch Rexroth is showing its electronic Diesel Hydraulic Control (DHC) system, which the company said provides higher dynamics at lower engine speeds. DHX from Rexroth combines diesel engine and hydraulics control. According to Rexroth, the intelligent integration of hydraulics and diesel engine control retains the dynamics of machine functions even with Tier 4 final engines and enables fuel-saving without sacrificing overall performance.
DHC has been developed together with diesel engine specialists from Bosch. The solution for engine management as well as drive and working hydraulics reduces diesel fuel consumption by up to 20% according to the company.
The Tier 4 emissions regulations for mobile work equipment will likely result in significantly poorer load response of diesel engines, said Rexroth. Furthermore, manufacturers of excavators, telehandlers, and other mobile work equipment are reducing engine speeds in order to consume less diesel fuel. The control devices used until now for the drive and working hydraulics cannot compensate for this sluggishness, said the company, and the potential risk is lower productivity.
Rexroth has teamed with Bosch to develop a new control strategy which it said retains the accustomed lively response of the travel drive and implement hydraulics even under conditions of diminished load response and lower engine speeds. DHC changes the traditional function sequence and lets the diesel engine know of expected load requirements. This is accomplished using matched controllers from Bosch for engine management and from Rexroth for the travel drive and implement hydraulics.
Rexroth said that DHC continuously determines the demands and uses this information to calculate the optimal operating points for the diesel engine and hydraulic components. In practice, the joystick for the implement hydraulics, for example, 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, said Rexroth. It said that the world’s first combined controller solution compensates in this way 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, thereby saving fuel, said the company. DHC means that the diesel engine only provides as much power as the machine actually needs at any given moment, thus reducing fuel consumption, it said.
