Electro hydraulic drives: The Fitness program

Electro hydraulic drives: Made in heaven

Jake Mitchell of Bosch Rexroth highlights the role of electro hydraulic solutions in modern industrial applications.

Established for more than 200 years as an efficient and convenient way of delivering power to a myriad of industrial applications, hydraulic systems today remain at the heart of industrial processes across an enormous spectrum of sectors.

The advantages of hydraulics and Industrie 4.0

The advantages of hydraulic systems remain clear. Cost-effective and reliable when compared with the alternatives, the sheer quantity and density of power they can deliver means that in some high-demand applications they remain the only option. Highly resistant to impact and vibration, they can also fit into tight spaces thanks to their compact design.

As is the case with any other system within industrial processing, designers of hydraulic products and systems are continually evolving their technologies to keep pace with other areas of modernisation, not least as the drive towards Industry 4.0 gathers momentum.

Adoption of Industry 4.0 requires a level of connectivity with other systems, along with the ability to monitor and respond proactively to actual and anticipated performance issues that, in many instances, would not even have been considered 20 years ago. This goes hand in hand with a broader desire among many manufacturers to understand in detail the workings of individual systems, the issues affecting them and best practice in maintenance.

The electro hydraulic drives and the possibilities

However, it would be wrong to suggest that Industry 4.0 is the only driver of change in the area of hydraulics. In all sectors, pressures on prices and rising energy costs require manufacturers to examine all aspects of design and operations to ensure they are as efficient as they can be. Meanwhile, increasingly stringent local, national and international regulation, in areas such as sustainability, environmental practice, and health & safety, require system designers to seek to integrate intelligent components such as smart controllers, sensors and monitoring technologies into their hydraulic systems.

 

In short, modern hydraulic systems must deliver efficiency, safety and connectivity, allowing ongoing condition monitoring (and response to changes in condition), while not compromising on their unique power delivery capability. This has driven the development of hybrid or electro hydraulic solutions which combine the power capabilities of hydraulics with the efficiency, safety and connectivity benefits of electrical and electronic systems.

In fact, electronification further extends the power capabilities of hydraulic systems as it offers the possibility of more sophisticated motion control sequences, ensuring torque is optimally employed across a range of applications. Drawing on Bernoulli’s law that, in an ideal state, a faster-flowing fluid will exert less pressure, the very latest sensors and hydraulic controls enable improved flexibility and variability in flow and pressure to deliver optimised performance when it comes to torque.

The variable speed and the meaning for connected hydraulic drives

Furthermore, intensive research and development efforts by the leading players in the sector have now made software-based automation a real possibility. This means hydraulic systems in many applications can be controlled with exactly the same tools as electric drives, bringing the benefits of hydraulic systems within the scope of design engineers who were previously denied this opportunity by the limits of their knowledge and training.

Electro hydraulic drives solution: the variable speed pump drive

Electro hydraulic drives solution: the variable speed pump drive

The latest system solutions for electro hydraulic drives employ the same electronic control assemblies and logic as electric drives. Using open standards such as Multi-Ethernet interfaces, they can be added to horizontally and vertically networked machine architectures in exactly the same way. Electro hydraulic axes are put into operation with the same engineering tools as electric drives, but with two clear distinctions. Firstly, a ‘wizard’ logically guides the technician through the commissioning of hydraulic axes and suggests parameterisation values which will lead to the desired result. Second, best-in-class controllers intelligently compensate for the special features of fluid technology in the background. The key point is that commissioners of systems do not need to have any specific knowledge of hydraulic systems to gain effective results from these technologies. Meanwhile, the latest variable speed pump drives can cut the energy consumption of hydraulic axes by as much as 80 per cent.

Recent years have seen almost all motion patterns and special features of fluid technology modelled in modular software – even specific characteristics such as transmission kinematics and controlled synchronisation. Distinct online configurators for components and modules are now available, with simulation tools checking all components for proper dimensioning and allowing designers to virtually test a wide variety of configurations. Modern solutions are based on distributed intelligence and open standards for programming and communication. Moreover, cabinet-free motion controllers can further simplify designs.

What this means is that the suitability of electro hydraulic drives for any application can be evaluated, and automation implemented, in the same way as with any other technology

Predictive Maintenance approaches for electro hydraulic drives

Digital twins of hydraulic components now support simulations and software-controlled process changes, while networked hydraulics monitor and detect errors with a probability of 99 per cent before they result in a failure. Specialist sensors can acquire information on various operating conditions in hydraulic power units such as oil quality, temperature and vibration, as well counting the switching cycles of valves, feeding this back in real time to control systems and allowing appropriate precautions to be implemented proactively and in planned production breaks.

Electro hydraulic drives offer unique power density, efficiency and robustness – with system design, parameterisation, commissioning, operation and software-based diagnostics which are just as convenient as for other drive technologies.

With digital intelligence, networkable hydraulics can now be seamlessly integrated into multi-technology and Industry 4.0 concepts, meaning they are and will remain a vital component of modern mechanical engineering.

“Variable speed is the key”: Read more

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