The main advantage of Hainzl's servo inverter-controlled hydraulics is that they can be used independently of a central hydraulic supply. © Kollmorgen

The main advantages of the so-called servo inverter-controlled hydraulics, however, lie above all in the wide range of possible applications, without having to compromise on whether the hydraulic supply is provided from a central unit in a process area. "We make the high power density of hydraulics more easily available," says Schrenk. Cables are easier to lay than hydraulic pressure lines. Furthermore, the compact units work with significantly less hydraulic oil and are only in an active operating state when the connected process actually requires the hydraulic power. In contrast, central systems must always maintain the operating pressure - especially when hydraulic axes work in a time-delayed manner in production processes. According to the company, the servo inverter-controlled hydraulics are ready for operation from a standing start thanks to the highly dynamic servo motor from Kollmorgen's AKM series.

This design improves energy efficiency in the long term, as losses in standby mode no longer play a role. This is accompanied by a longer service life of the hydraulic medium, as the oil is subjected to less mechanical stress and therefore does not age as quickly. This should result in lower costs for operating materials and higher availability due to longer maintenance intervals. The longer service life of the fluid as a result of the targeted use of hydraulics also ensures that the ambient temperature does not rise excessively - this as a result of an overall reduction in power loss. And where less "waste heat" is generated, OEMs and machine operators also have to worry less about how to control or reduce the rising temperatures in their processes. On the motor side, Kollmorgen also makes a valuable contribution to reducing heat input, as the AKM servomotors generate low thermal power losses due to their high efficiency. In addition, the synchronous servomotors operate without external fans.

No braking power in the hydraulics

Construction of a servo-hydraulic unit from Hainzl with servo drive technology from Kollmorgen. © Kollmorgen

The negative influence of heat on service life and energy efficiency also has an effect outside of partial load and standby mode - specifically when braking forces are acting on the hydraulics. Hainzl uses Kollmorgen technology, for example, to perform handling tasks as part of intralogistics processes. This involves lifting and lowering heavy steel parts. With centralized hydraulics, the kinetic energy generated during lowering can only be absorbed via the oil in the form of heat. This has the consequences described above - including additional cooling measures, which further reduce the overall efficiency of a machine (keyword OEE). "The electrohydraulic system developed together with Kollmorgen makes it possible to allow the braking energy to act directly on the motor," explains the Head of Fluid Technology at Hainzl. This enables the Austrians to feed back the braking energy elegantly and, above all, energy-efficiently, especially in constantly recurring lowering sequences.

Conclusion

With the prepared servo pump drive solution, Kollmorgen has developed a new function for electrohydrostatic actuators (EHA) based on the S700 servo controller series. The software-based application can be easily adapted to the special features of the application during engineering by parameterization. This creates the basis for utilizing the advantages of the EHA without having to consider possible restrictions of existing central hydraulics. Kollmorgen supports this approach with a modular and, above all, open drive solution that can be easily integrated into the existing automation network.