Electrification of construction machines
We are talking about the electrification of construction machinery, a topic of absolute interest in the current technical and technological panorama.
Construction machinery is widespread and operates, in standard current conditions, thanks to the power supplied by an internal combustion engine.
Hydraulic systems offer great power density (compact transmission components and actuators) and great robustness.
However, the interest in systems that can work in closed or confined spaces and the need to reduce emissions, push machinery manufacturers to evaluate hybrid or electric solutions.
The typical starting point is to evaluate the hourly or kilometer energy needs for the endothermic vehicle.
Just to make it clear, this approach is wrong. But why?
In order to understand that we need to take a step back and try to look at the electrification process as a revolution, not as an evolution.
“If I had asked people what they wanted, they would have said faster horses .”
– H. Ford.
The electric motor is the starting point of an electrification project. Unlike the internal combustion engine, the electric motor provides torque at zero rpm similar or equal to the maximum torque.
Think of a crane, where the internal combustion engine is kept running at idle speed in order to be ready to respond by delivering the maximum torque or maximum power where a hydraulic pump needs to be operated. The consumption at idle of the internal combustion engine is effectively zeroed with the electric motor!
It is necessary to make a general consideration on the POWER BALANCE OF SYSTEM. It is true that the energy density of a liter of fuel (petrol, diesel, methane or similar) is extremely higher than the energy density stored in a volume equal to a liter of lithium battery, it is also true that the complete yields of the distribution chain are significantly higher in the case of the electric.
“If I have seen farther than others, it is because I was standing on the shoulders of giants.”
– I. Newton
The technology of inverters and electric motors is already extremely advanced and efficient. Thanks to the development carried out by the manufacturing industry over the years and thanks to the energy efficiency imposed by the regulations (IE2, IE3 , IE4, …) by now widely spread, it is advisable to carry out a evaluations of the entire starttrain and powertrain system while starting to tackle an electrification project.
The best results, based on our experience, are achieved where efficient solutions for motors and inverters part are identified with a correct electrical sizing of the battery, reconciling high efficiency with the need to reduce the impact of the system on the mechanical design vehicle and on the interface with existing parts (SAE flanges, pumps, actuators, axles).
For these reasons, our first approach to new projects is always oriented to an overall technical and technological aspect.
