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VSD-based hydraulic pack cuts energy use by up to 80%
Rexroth has developed a hydraulic power pack for machinery that integrates all of the hydraulic and electrical components, along with a variable-speed drive, to produce a compact system that can cut energy consumption by up to 80%. The plug-and-run CytroPac system also simplifies commissioning and maintenance.
The cylindrical pack integrates hydraulic components, a motor, pump, sensors and a VSD in an IP54 housing that avoids the need for a cabinet. It handles power ratings up to 4kW and flow rates up to 35 l/min.
The built-in VSD, based on a Rexroth Sytronix drive, matches the pump motor speed to demand. It is claimed to use 30–80% less energy than constant-power systems, depending on the cycle characteristics. The demand-based speed control also reduces heating of the hydraulic oil, thus cutting cooling requirements. A space-saving heat-pipe system uses water for cooling.
The VSD is connected to sensors for pressure, temperature, oil level, clogging and flow. Constant condition monitoring means that wear and other faults can be spotted and corrected at an early stage. The VSD communicates with machine controllers via a choice of real-time Ethernet interfaces, including Sercos, Profinet, EtherCat, EtherNet/IP and Modbus/TCP, as well as Profibus. Operators can change pressure and flow rates remotely in real time via the Ethernet connection.
The pack includes a 20-litre hydraulic tank, which helps to reduce the system’s dimensions. It is said to ensure correct degassing of the oil, thus prolonging the service life of the fluid.
To commission the pack, the only connections that need to be made are to a power supply, the controller, and the hydraulic and cooling water circuits
The housing reduces noise levels, avoiding the need for space-consuming and costly housings to comply with noise-restriction regulations.
