ST 022-10 Lohr, 2010-04-14

Call for energy-efficient hydraulics: mission accomplished. BlueHydraulics by Rexroth saves energy, increases efficiency and reduces emissions

Significantly lower energy consumption resulting in reduced carbon and other exhaust emissions at the same performance levels as before: Machine manufacturers and end users are beginning to focus on precisely this set of demands. Rexroth's BlueHydraulics take up the challenge through implementation of efficiency-optimized components, innovative modules and networked system solutions. The market leader in hydraulics presents simultaneously at the BAUMA and the Hannover Messe its wide array of sustainable solutions for mobile applications, factory automation and plant equipment.

The German government has imposed industry-related CO2 emission reductions of 20 percent below 1997 levels over the next ten years. Although such reductions mean significantly lower energy consumption, many companies are setting their sights even higher in order to contribute more actively to climate protection. The Bosch Group, having pledged to reduce its carbon emissions by 25 percent, belongs to this category of companies.

For mobile applications, the line of demarcation is drawn by the much stricter limits set forth in the TIER 4 Final Rule. By 2014, machine builders will have to comply with limitations that until now have been out of reach. Preliminary studies indicate – in addition to exhaust-gas treatment systems – a trend toward smaller diesel engines and lower RPMs. Both trends call for innovative thinking in the fields of implement and travel drive hydraulics in order to continue at present performance levels even after changing the characteristics of the drive motors.

Rexroth's expertise in the area of hydraulic drive technology responds to these demands directly and effectively with the wide array of products and solutions included in the BlueHydraulics program. System designers orientate themselves on the Rexroth 4EE levers for greater energy efficiency. Via these – Efficient Components, Energy on Demand, Energy Recovery and Energy System Design – they tap the great wealth of possibilities for higher cross-applicational design efficiency. In so doing, they are continually optimizing the efficiency of components, developing new functional properties, and designing new system solutions for higher energy efficiency.

Adaptable hydraulics

Over time hydraulic solutions have proven to be highly adaptable to changed and changing conditions. The introduction of proportional technology improved the controllability of hydraulic solutions that had functioned up to that point only in the on/off mode. Once decentralized automation technology became more and more prevalent, electro-hydraulics began to profit from the progress made in digital control electronics. The result: significantly higher dynamics and precision of hydraulic actuators that can be inserted via the distributed intelligence into the widest variety of automation environments. The shift of functions to the software has given rise to additional flexibility for new functional properties that do not require changing the hardware.

It is precisely this linkage of software-based demand control apparati and efficiency-optimized components that will yield the most savings in energy consumption. As the only manufacturer of all varieties of drive and control technologies, Rexroth combines its profound expertise in hydraulics with distinctive software skills. With its many system solutions for both mobile and stationary applications, BlueHydraulics by Rexroth provides the means to exploit these possibilities in order to save energy, increase efficiency and reduce emissions – all of which at the end of the day means lower costs of ownership.

Mobile applications: Smaller motors and reduced engine speed

Mobile hydraulics can profit greatly from the digital networking of all compatible components and functional properties. These system solutions are clever ways to facilitate the downsizing of diesel motors or the reduction of engine RPMs in order to reduce diesel consumption while maintaining at least the same performance levels as before. Conversely, such solutions – even in respect to today’s standard motor concepts – give rise to significant reductions in consumption and emissions. In this way, for example, Diesel Hydraulic Control (DHC) combines motor management with controls for implement and travel drive hydraulics. As Helmut Wagener, Chairman of the Hydraulics business unit at the Bosch Rexroth AG, puts it: "Rexroth's Diesel Hydraulic Control is enhanced by the unique synergies stemming from our relationship with Bosch, the world leader in motor electronics." Via the combined demand control, DHC can reduce consumption by up to 20 percent. Most importantly, the system solution ensures that the same amount of power will be available to the machine as there was prior to optimization. This holds true even in the case of diesel engines with sluggish load assumption properties – as expected in the course of the TIER 4 Final Rule.

Other system solutions, like the Hydrostatic Regenerative Brake System (HRB), exploit the braking process to allow the hydraulic storage unit to recover the deceleration energy and make it available for the next acceleration. This system is especially useful for such applications as garbage trucks or busses, both of which are constantly braking and accelerating. In practice, HRB reduces fuel consumption by up to 25 percent. Hydraulic Fly Wheel technology takes up where HRB leaves off. In addition to enabling energy recovery, it can be implemented for power smoothing, booster functions or can clear the way for a downsizing of the diesel engine.

Innovative functional properties can also qualify well-known components for inclusion in the BlueHydraulics family of products. Rexroth system designers, therefore, are hard at work optimizing component efficiency. The higher pressure levels and speeds of the A4VG variable displacement pump for the new Series 40, for example, result in significantly enhanced power density. Green valves, the load-holding and lowering valves, utilize the force of gravity rather than the diesel engine's valuable supply of energy. This reduces the power requirements, freeing up a higher volume flow for functions working in parallel.

In the words of Helmut Wagener, "BlueHydraulics enables OEMs to continue using the compact hydraulic solutions they have grown accustomed to in order to save energy, increase efficiency and, above all, reduce exhaust emissions to TIER 4 final-compliant levels."

Increased efficiency for stationary applications

BlueHydraulics by Rexroth also means increased efficiency in the areas of factory automation and plant equipment. Variable-speed pump drives, for instance, cut energy consumption by an impressive 30 to 70 percent. "We have achieved savings of more than 80 percent in respect to the servo-variable pump drives in die-casting machines," says Lucas Wintjes, General Manager of Sales, Industrial Hydraulics, at the Bosch Rexroth AG. "That means lower operating costs and a return on investment within one year."

The innovative, patented cooling and lubrication booster (KST-booster) is yet another example of the energy-saving potential provided by BlueHydraulics in the area of machine tools. Here the pressure supply for the high-pressure cooling oil circuit is integrated into the hydraulic power unit. An additional linear pump replaces the conventional screw spindle pump. The result is that the KST booster reduces the energy requirements of the high-pressure cooling oil circuit – so necessary for chip-breaking functions and for cooling the tool interior – by almost 90 percent in comparison to conventional solutions. By combining variable speed pump drives and the KST-booster users can profit, in part, from cumulative savings. For machine tools, energy costs comprise around 15 percent of the total life cycle costs.

Via analog, fieldbus or industrial Ethernet, solutions provided by BlueHydraulics can be integrated perfectly into each and every automation environment. Commissioning is also simplified due to the pre-parametered software. The finely-scaled line-up of speed-variable pump drives (SVP drives) covers a wide range of applications, including, among others, machine tools, injection molding machines, presses and all types of cyclically working equipment. Two important extras: SVP drives lower mid-range noise levels significantly, which often alleviates the need for special sound-damping enclosures. In addition, the demand control reduces the amount of heat transfer to the hydraulic oil, and thus the energy required for cooling.

At the component level, BlueHydraulics means increased energy efficiency. The new internal gear pump PGH-3X, for instance, has been optimized to support the variable speed pump drives and can now muster up to 3000 RPMs and more across the entire speed range.

System designers can make a huge difference in the energy efficiency curve – even in the project planning phase. And this is especially true in respect to factory automation and plant equipment. A modular hydraulics extending into the component level offers numerous possibilities to reduce energy consumption: storage charging circuits, to name only one. Our project engineers, specialists in the widest variety of industrial applications, support our system designers with their expertise and sharp focus on the thoroughgoing and consistent "Energy System Design" made possible by BlueHydraulics by Rexroth. "What we offer machine manufacturers," says Lucas Wintjes, "are precisely those solutions that fulfill the customers' demands for energy savings, increased efficiency and reduced emissions."

Bosch Rexroth AG is one of the world’s leading specialists in the field of drive and control technologies. Under the brand name of Rexroth the company supplies more than 500,000 customers with tailored solutions for driving, controlling and moving. Bosch Rexroth is a partner for industrial applications and factory automation, mobile applications and using renewable energies. As The Drive & Control Company, Bosch Rexroth develops, produces and sells components and systems in more than 80 countries. In 2008 Bosch Rexroth AG, part of the Bosch Group, achieved sales of around 5.9 billion Euro with 35,300 employees.

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Image 1:

"BlueHydraulics enables OEMs to continue using the compact hydraulic solutions they have grown accustomed to in order to save energy, increase efficiency and, above all, reduce exhaust emissions to TIER 4 final-compliant levels." (Helmut Wagener, Chairman of the Hydraulics business unit at the Bosch Rexroth AG)

Image 2:

"What we offer machine manufacturers are precisely those solutions that fulfill the customers' demands for energy savings, increased efficiency and reduced emissions." (Lucas Wintjes, General Manager of Sales, Industrial Hydraulics, at the Bosch Rexroth AG)


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