How to control hydraulic flow rates more efficiently
Eaton has published a white paper that provides background and approaches for reducing energy consumption in applications where flow rates need to be controlled. Using hydraulic power units as an example, the white paper - entitled Planning and operating hydraulic power units to provide greater energy efficiency - explains how and why the choice of drive concept for hydraulic pumps can have a significant impact on energy and life cycle costs.
Machine and system builders can achieve energy savings of over 50% if they use variable speed drives. At the same time, they benefit from lower heat generation, and thus reduce cooling requirements. Other important benefits include achieving a more compact design and reducing pump noise level. The paper also discusses and explains the role of power management and the contribution that an intelligent wiring and communication system can make in preparing machines for the Internet of Things, i.e. in making machines IoT-ready.
Author Marco Bison, manager of mechatronic technologies at Eaton, investigates the cost and energy efficiency of the drive concepts currently available for hydraulic pumps. He explains that, while the continuous constant-speed drives used today only require a low investment, they result in high energy costs. One alternative solution would be direct drives with servo motors; using these would significantly reduce the energy consumption of a hydraulic unit; however, these require a relatively large investment. Bison suggests that a variable speed drive with an asynchronous motor driven by a variable speed starter or a frequency inverter is a cost-effective and energy-efficient solution. The flow rate of the pump and the pressure in the hydraulic system are controlled by the speed. The drive only provides the power that is actually required of the hydraulic devices at any particular time (Power on Demand). This means that significant energy savings are possible, as Bison proves by giving a practical example of a retrofit measure on an injection moulding machine.
The white paper also shows that reducing the energy consumption of a hydraulic unit is only a first step towards creating a highly efficient system. The next is to create the right conditions for a power management system. This requires comprehensive recording and analysis of energy and machine data. Replacing the current standard of complex point-to-point wiring with an intelligent wiring and communication system provides a cost-effective approach to this. This not only reduces the wiring workload, but makes it easier to integrate simple automation devices – such as motor starters, sensors or actuators – through easily installed intelligent communication modules. This means they can communicate with each other and can, with minimal effort, deliver the data required for an analysis and have the ability to connect the hydraulic power unit to the Internet and the Cloud so that the energy and operating data can be accessed from anywhere in the world.
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