written by Pascal Kiwitz, Rosita Ungerank

From the traditional to the electrically powered machine

All signs point to a traffic revolution. Electrification was already being talked about more than 100 years ago, when the operation of railway lines was switched from coal to electricity. In addition to e-mobility in the passenger car and commercial vehicle sectors, the electrification of mobile machinery is also currently presenting us with a major challenge. To this day, attempts are being made to reduce CO2 emissions from diesel engines by means of various optimization approaches. However, the burning of fossil fuels is one of the main causes of the greenhouse effect. As a result of the gradual, climate-neutral rethinking, diesel engines are increasingly being replaced by electric motors with inverters and batteries for machines in the power range up to 50 kW.

However, just replacing the internal combustion engine with an electric motor while continuing to use the other system components, such as hydraulic pumps and hydraulic systems architectures, simply results in a noisy and inefficient system. The noise emissions from the axial piston pumps are much more audible at the constant high speeds of the electric motor, now that the loud internal combustion engine is eliminated. In addition, the advantages of electrical drive technology – the high torques at low speeds – cannot be used due to the inadequacy of the other existing components. The "electrified diesel machine" therefore consumes energy unnecessarily: the attempt at electrification fails because of the available battery capacity, which is dissipated in power losses due to the poor overall efficiencies of the existing systems architectures.

As a sustained and sustainable strategy for a climate-friendly future, changing from a traditional to an electrified machine in power ranges below 50 kW is entirely valid. However, in order to achieve high efficiency and cost-effectiveness, the use of the appropriate systems architecture is crucial.

Electrical equipment

Load-sensing systems often do not fully meet the requirements for electrified machines. Elaborate damping is necessary to operate the system without oscillations, variable-displacement axial piston pumps are noisy, and the control pressure difference causes unnecessary losses at most operating points. Compared to a load-sensing system, the Flow-On-Demand solution is more efficient, more stable and more dynamic.

Introducing the Flow-On-Demand flow distributor system

Standard hydraulic components continue to be installed. In contrast to a classic diesel-powered machine with load-sensing control, here we control the flow rate or the pump speed. The sum of the actuator flows corresponds to the pump's target flow rate, which is converted directly into a speed.

Advantages
Direct control
  • Improved system stability
  • Damping in the system can be reduced or even eliminated
  • Agile and responsive system, as it is "directly attached to the joystick"
Noise reduction
  • Noise level drops to a minimum due to the pump speed being matched to the flow requirement
Energy efficiency
  • Multiple increases in efficiency
  • The swashplate pump requires some flow for its own adjustment – which reduces the efficiency of the pump. By using a fixed-displacement pump, the efficiencies are generally higher.

Flow rate ranges of AX pumps 

Flow-On-Demand in combination with our AX pump

The greatest potential for reducing energy requirements is to be found in combination with our highly efficient axial piston pump.

The new AX pump from Bucher Hydraulics revolutionizes the electrification of mobile machinery. As the heart of the system, its special significance lies in variable-speed operation in order to meet the particular requirements of a Flow-On-Demand system. The controller ensures the optimum speed, noise emissions remain low and only the necessary energy is consumed.

Advantages
  • Our AX pump is the most efficient fixed-displacement axial piston pump ever, which increases the efficiencies even further
  • There is no limit to the minimum speed of the AX pump, which means that even very low flow rates can be suitably catered for
  • Pump does not use any energy if there is no demand for flow
  • Available in size 24, 48 and 76 and recently also in size 122

Let us convince you of the main advantages of a Flow-On-Demand system!

Cost savings, less noise and increased availability are bringing us together as we pursue the goal of highly efficient, electrified machines.

Please contact us. Together we will find the power management solution that is individually tailored to your needs!

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