The soaring prices of resources and energy have led to higher and higher construction costs. In addition to climate change, high cost is another reason why construction machinery needs to save fuel. Scientists at Karlsruhe Institute of Technology (Kit) studied the possibility of improving operating efficiency by taking a hybrid driven hydraulic excavator as an example. They found that about 10% of the savings potential can be further improved by special software that controls the operation of different drives.
Hybrid drive is a combination of several different energy storage and driving technologies, which has long been established in cars, such as the combination of gasoline or diesel engine and electric drive. Construction machinery already has several driving devices: propulsion driving device, rotary driving device and work driving device. All of these may be hybrid drive, but at present, all drive systems of most excavators are equipped with diesel engines.
"We studied different hybrid measures to identify their potential efficiency improvements," said Niklas Bargen of the vehicle systems technology institute.
The results show that when the electric drive is used in the rotary system of the excavator - that is, the drive that allows the excavator to rotate laterally - the efficiency is improved by 11% and the fuel is saved by about 8%.
By lowering the excavator arm to recover additional energy (similar to the regenerative braking system in electric vehicles), the efficiency may be improved by 12.5%. According to Bargen, the potential savings are 9% fuel. Researchers even expect further savings potential. For example, by using a software, the software can continuously determine which driver to use for different functions of the excavator according to demand and efficiency.
Scientists at mobima equipped excavators with many sensors for their research. They worked at different construction sites for 100 days and closely monitored the 15 ton machine.
"Then we simulated different hybrid variants on a computer and calculated their potential to improve efficiency in practice," Bargen explained.
Considering that the estimated fuel consumption of a medium-sized excavator in its life cycle is 100000 litres of diesel, the hybrid drive in construction machinery has considerable energy-saving potential. However, researchers believe that hybrid power is more a bridge technology on the road of full electrification of construction machinery. Due to its high energy consumption and insufficient storage technology, it still faces great obstacles.
