CytroBox: Hydraulic power unit or household refrigerator?

Connecting machines and industrial facilities with IT systems hold enormous potential for making production more economical, quicker and intuitive. And while some naysayers see IoT as more hype than reality, the engineers at Bosch Rexroth are making it a practical reality. The company’s new CytroBox hydraulic power unit, with its sleek, intelligent and energy-efficient design, integrates IoT technologies and helps pave the way for implementing Industry 4.0 concepts.

“The intention was to move to the next step of innovation in the field of hydraulic power units,” said Steffen Haack, President Industrial Hydraulics at Bosch Rexroth, Lohr am Main, Germany. Compared to conventional power units which haven’t markedly changed in decades, the company collaborated with its customers to integrate the latest technology offerings into a new type of power unit, he explained.

“And in the end, we wanted to change the perception of industrial hydraulics and power packs. When you look at the stamping lines of a Ford, GM or Chrysler, power units are mounted in the ground, they’re dirty, noisy and leaky, and no one wants to go near them. Our idea was to make a power unit that you can put in your living room, it looks like a refrigerator and runs silently. We believe this is a new approach for hydraulics, compared to what has been done for the last 30 years,” he said.

The unit has a number of key features that set it apart from a typical power pack, according to Haack. Flow is controlled by a fixed-displacement A10 axial-piston pump driven by an Indramat MS2N synchronous servomotor. The variable-speed pump drive adjusts energy requirements as needed. Speed is reduced under partial or no load to save energy and, conversely, increased under full load with a highly dynamic response. This results in energy savings of up to 80% compared to constantly driven power units.

A 3D-printed manifold block also contributes to efficient operation. Additive manufacturing techniques let engineers create more-refined channels and make the manifold 40% smaller than a comparable machined manifold. This improves oil-flow characteristics, reduces pressure losses and minimizes potential leak points, as fewer plug screws are required.

A rotomolded polymer tank also contributes to the CytroBox’s small footprint. Engineers used CFD simulation to optimize flow and degassing and, as a result, the necessary oil volume decreased by 75% – from 600 to 150 litres. A water-cooled heat-exchange circuit keeps oil and motor temperatures low.

And the unit is quiet. Internal airborne sound is absorbed by the compact arrangement of all the components in a unitary housing with built-in sound insulating mats. To reduce structure-borne noise emissions, the motor-pump group is rigidly affixed to a polymer-concrete foundation with high damping efficiency — a technique that’s typically used in machine-tool installations.

In contrast, the mounting pads of conventional power units readily transmit noise and vibration to the tank. Consequently, noise emission of the CytroBox is less than 75 dB(A) —even at full load. Comparable power units average noise levels of 85 dB(A). For the user, this eliminates the need for costly noise-reduction measures and improves the work environment, even in direct proximity to the hydraulic power unit.

The CytroBox includes an extensive sensor package and open interfaces, which makes it well-suited for connected environments. Integrated and wired sensors — including water, leak, particle level, temperature and filter-condition sensors — track information regarding the current filter, oil and drive status, and it is the first power unit that uses an IO-Link master as standard. Collected data are processed by the drive controller.

The CytroConnect software integrated into the unit takes advantage of this data to monitor the main operating states and analyze them online. A dashboard shows maintenance technicians all the relevant parameters and provides important maintenance instructions. That includes performance and operating data, oil level, oil quality and temperature over time. The units automatically record this data, pre-process and send it encrypted into a cloud. Using the browser-based interface, technicians can wirelessly dial into the CytroConnect service and retrieve the data independently, regardless of location.

As a plug & play solution that is already installed in the CytroBox, CytroConnect requires no additional installation effort. Rexroth provides the basic functions of the software free of charge in a Freemium model for all CytroBox power units. Machine manufacturers and end users can also incorporate two additional options via a subscription model.

The “Maintain” module reports rule-based errors as a push service, processes additional status information and provides maintenance instructions. The pre-implemented rules not only help the users but also form the basis for condition monitoring. The rules can even be adapted to individual requirements without programming.

The “Predict” service package uses the machine-learning algorithms of Rexroth’s Online Diagnostics Network (ODiN). Bosch Rexroth has integrated its hydraulic domain know-how into the software and uses analysis algorithms to create a health index for the power unit. These analyses provide the building blocks for predictive maintenance concepts and, thus, maximum availability.

System builders, machine manufacturers and end users can integrate CytroConnect as a module into their own digital IoT maintenance concepts and use it as a complete solution for comprehensive condition monitoring.

With its intelligent and energy-efficient modular design, the CytroBox hydraulic power unit provides a new option for the medium power range from 7.5 to 30 kW. The company intends to develop larger units, with the limit of this concept around 100 kW, said Haack.

It requires 50% less installation space than conventional units, and with noise emissions of less than 75 dB(A) – even at full load – is particularly quiet. By integrating IoT technologies, it also paves the way for flexibly implementing Industry 4.0 concepts into existing production lines.



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