046-11 Lohr, 2011-05-02

CeMAT 2011: Building blocks for mobile machines of the next generation

Mobile Machines

CeMAT 2011: Building blocks for mobile machines of the next generation

Many innovations in detail are the basis for so much progress being possible on the whole. At CeMAT 2011, Rexroth is therefore presenting innovative components that increase energy efficiency and performance. It is also presenting intelligent subsystems where synchronized assemblies facilitate compliance with environmental regulations, without having to make any compromises in functionality.

A typical example is SILENCE PLUS, a new external gear pump that was awarded the Industriepreis 2011 as being the most innovative product at Hannover Fair this year. When compared to a conventional external gear pump, SILENCE PLUS reduces the noise by an average of 15 dB (A). In spite of this, with a pressure range of up to 280 bar, it is still suitable for high performance applications.

The nearly silent hydraulics extends the advantages of quiet electric forklifts and electric lift trucks. Noise reduction is an important aspect, particularly in environments where there is direct customer contact, such as in supermarkets and beverage stores. But even in warehouses, where many employees are affected by noisy work equipment, systems with quiet Rexroth pumps present a contribution to their well-being. The investment will also pay off by bringing down expenses for noise insulation. Because of it, many work processes can be omitted during installation.

Maximum performance with minimum energy consumption

With modern hydraulics, Rexroth proves that efficiency does not mean having to do without important technical features. With another core component, the variable displacement pump, Rexroth offers particularly low-maintenance and economic hydraulic solutions.

According to the "Flow on demand" principle, only as much oil as is actually required will be supplied by the A10VO variable displacement pump. Depending upon the required capacity, reducing the swivel angle makes it possible to regulate the flow and so reduce the energy consumption considerably. In addition, the service life of the hydraulic fluid is extended, and thus longer service intervals are possible.

Subsystems with integrated system solutions

Even today, the powerful individual components from Rexroth are already giving engineers the systems for meeting the demands that will be arising. Starting in 2014, when the even more stringent emissions standards in the TIER 4 final rule take effect, more environmentally friendly and cost-efficient components will be needed. However, the requirements are set so high that individual components alone will often not be sufficient.

For this reason, Rexroth is offering a line of synchronized assemblies that manufacturers of mobile machines can use to solve engineering tasks very efficiently. Whether it is for hydrostatic drive, working hydraulics, steering or operation - the subsystem can be easily integrated into the individual concepts of manufacturers and can accomplish clearly delineated individual tasks.

For example, the hydrostatic drive can form the combination of wheels and internal combustion engine in a variable manner. The hydraulic unit can absorb load changes very efficiently, so the engine does not have to work unnecessarily in its upper rpm ranges. Through the precisely metered oil flow, hydrostatic units can be moved and positioned with great accuracy. Via software, performance management permits a choice between maximum handling performance and minimal energy consumption. In this way, despite the fact that consumption is optimized, the user always has the required power available. Another advantage is that wear-free, hydrostatic brakes with retarder support increase the service life of the system and reduce operating costs.

Other subsystems, such as the Rexroth power packs, also allow more compact, electrohydraulic solutions, because all the valves are fully integrated into the unit. Since the tubing that would otherwise be required is not necessary, the costs are reduced. In addition, less labor is needed during installation and the compact power packs also occupy little space.

Gaining efficiency through precise controls

Intelligent systems require high-performance controls. At CeMAT, Rexroth will present a new representative of the Series 30 BODAS RC control devices. Numerous valves, hydraulic pumps and motors, as well as electrical equipment, can now be controlled with a single device. The RC28-14/30 controllers replace decentralized solutions and make it easy to integrate components into the control concept, components that are now still often controlled mechanically.

The new controllers have 28 proportional outputs, 14 switching outputs and 75 multifunctional inputs. A fast TriCore processor ensures that even complex programs are processed with short cycle times. The control platform allows it to present safety features up to Performance Level d, in accordance with ISO 13849, with only a single controller. The programmable controller with a CAN bus connection can control the hydrostatic drive, the hydraulics and the electrical auxiliary functions, both individually and collectively. It also has access to the engine controller so that it can, for example, require a more fuel efficient and demand oriented engine speed.

Precisely regulated electronics allow the precise interaction of pump and valves. This is important for the working hydraulics, which can spontaneously require high power, which must not be supplied to the detriment of other hydraulic components. Although the engine produces no power from reserves, mobile machines with intelligent controls achieve very high throughput. Since this is accompanied by low energy consumption, there is a positive effect on the Total Cost of Ownership.

Right from the start, the comprehensive BODAS toolkit, with its proven development environment (BODAS design), function libraries (C API), service tools (BODAS service) as well as existing, compatible software modules, gives the new RC control devices very great practical value.

Advantages through intelligent engine controls

The combination of electronic controls and hydraulics makes it possible to respond to particular situations and thus to increase efficiency.

This is clearly demonstrated with the Diesel Hydraulic Control (DHC) system. Here, Rexroth is drawing on the expertise of Bosch in regards to diesel engine controls to achieve high dynamics for the driving and working hydraulics at the lowest possible – and thus the most favorable for energy consumption - diesel engine rpm.

DHC increases the overall efficiency of the machine by hydraulics communicate to the engine management system. In this way, the working hydraulics can signal a pending work request to the engine, which then gains a crucial split second to prepare for the upcoming mechanical load. It does not get suppressed by the load, but can immediately exert its power. This maintains the momentum of the lift truck, even at the TIER 4 final optimized diesel engine standard. In addition, the control concept reduces fuel consumption significantly.

Another strategy for increasing efficiency is to increase the pressure level in the hydraulic circuit. When the efficiencies that are achieved allow smaller, more fuel efficient engines to be used, then the foundation has been laid for effective downsizing. Smaller engines typically weigh less and occupy less space in the engine compartment. For these engines, Rexroth offers suitable hydrostatic drives for the driving and working hydraulics. High pressure, axial piston units ensure that the hydraulic system always has the desired dynamics and power without requiring the diesel engine to operate constantly at its highest rpm level.

Energy recovery made easy

Mobile machines are supposed to waste as little energy as possible. For this reason, the Hydraulic Fly Wheel (HFW) was designed to temporarily store the excess or free energy from an engine. The HFW consists of a separate hydraulic system that absorbs the unused torque from the engine and uses it to convey oil into a storage unit. There, the pressure increases. The energy stored in this way is discharged by reversing the oil flow.

This is possible because the A10VO and A11VO Rexroth variable displacement pumps can swing "above zero" and therefore allow a change of pumps during engine operation while maintaining the direction of rotation. Because of its open design, the patented Rexroth Hydraulic Fly Wheel conducts energy from various sources into its accumulator. In this way, it is also possible to recover and store braking energy. The accumulator takes the load off the engine when acceleration again takes place after braking. Because of the additional oil flow from the storage unit, this does not need to be generated by the hydraulic pump. During load changes and frequent maneuvers, a boost function provides mobile machines with additional power and increases machine efficiency.

Rexroth at CeMAT 2011: Hall 25 at Booth B16.

Bosch Rexroth AG is one of the world’s leading specialists in the field of drive and control technologies. Under the Rexroth brand name, the company supplies more than 500,000 customers with tailored solutions for driving, controlling, and moving. Bosch Rexroth is a partner for Mobile Applications, Machinery Applications and Engineering, Factory Automation and Renewable Energies. The company provides customized solutions tailored to the needs and specifications of each individual market. As The Drive & Control Company, Bosch Rexroth develops, produces, and sells components and systems in over 80 countries. As part of the Bosch Group, Bosch Rexroth and its 34,900 associates generated approximately €5.1B in revenue in 2010.

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The Bosch Group is a leading global supplier of technology and services. In the areas of automotive and industrial technology, consumer goods, and building technology, some 285,000 associates generated sales of 47.3 billion euros in fiscal 2010. The Bosch Group comprises Robert Bosch GmbH and its more than 350 subsidiaries and regional companies in over 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for further growth. Bosch spent 3.8 billion euros for research and development in 2010, and applied for over 3,800 patents worldwide. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial.

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