When we consider the challenges facing the off-highway industry over the next 20 years, there is an important dynamic underway between the technological issues that our industry addresses in the normal course of doing business—such as better machine performance, cost control, equipment designs to fit tight machine spaces—and the larger societal issues, such as emissions control, climate change, and energy demand.
It is no longer possible to view these two sets of issues separately, and companies active in the off-highway industry have not only the opportunity, but also the responsibility, to offer solutions that consider both.
Across every industrial segment worldwide, climate change and environmental responsibility increasingly influence corporate behavior. More and more companies are committing to reducing the carbon footprints of machines and manufacturing—a commitment Bosch Rexroth shares and actively pursues, targeting a 20% reduction in our carbon footprint by 2020 compared to 2007 levels.
Additionally, our “local for local” strategy and GoTo focused delivery programs, besides bringing us closer to our customers, also help us reduce our carbon footprint by cutting our need for long-distance shipping. Further, we also have an opportunity to contribute to the effort to control greenhouse gas emissions and reduce carbon footprints in our development efforts for the on- and off-highway equipment industry segments.
In particular, there are opportunities to be smarter about the way energy is used in mobile machines, and at the same time make those mobile machines more flexible, more productive, and better equipped to deliver hardworking performance out in the field.
A systemic approach
Intelligent integration entails approaching the design, component selection, and integration of different mobile machine powertrain and drive components to maximize both energy efficiency and operational productivity. For Bosch Rexroth, our pursuit of this intelligent approach is called Rexroth 4EE: Rexroth for Energy Efficiency.
It is a systematic approach to help engineer energy efficiency into our latest drive and control technologies, including the high-performance hydraulics, electrohydraulics, and hybrid systems we supply to the industry. It uses four “levers” that on their own, or in combination, can have a dramatic impact on energy efficiency—which in many working machines, can translate into reduced emissions.
There are some who view hydraulics as a mature technology with limited opportunities for breakthroughs with impact. However, we have begun applying the 4EE concept with significant results. The first lever in our 4EE system is selecting the most energy-efficient components.
There are several examples of this approach. Our compact A1VO axial piston pump brings the fuel savings of load-sensing technology to the smaller power classes of mobile machinery. And for equipment such as telehandlers, wheel loaders, and skidsteer loaders, our intelligent, electronically controlled hydrostatic fan drive systems that use the BODAS RC electronic controls and the A1VO pump assist in keeping combustion engines operating at an optimum temperature while minimizing fuel consumption and emissions.
The second 4EE lever is energy recovery. If there is a waste of energy or an abundance of surplus energy—mechanical, electrical, or hydraulic—in a system’s design, then machine designers should consider technology that can recover, store, and re-use that energy. Rexroth’s HSS (hydraulic start-stop) system is a hybrid system that uses existing accumulator energy storage system technology with our proven A10V product and BODAS RC electronics. This system allows an engine to be shut off when the machine is not providing the primary work function, such as in a wheel loader, and then provides the stored energy to “start” the engine when the machine next needs power, saving up to 2000 L (528 gal) of diesel over the machine’s service life.
The third 4EE lever is energy on demand. Instead of running pumps and drivetrains at the same level at all times, energy on demand considers the hydraulic and control choices that can be made so that the machine uses only the amount of energy that’s required for the duty cycle at that moment. The HSS technology described above fits this category, as well, but an even better example is Rexroth’s DHC (diesel hydraulic control), which combines our experience with hydraulic controls with the diesel engine management know-how of our partners at Robert Bosch GmbH.
DHC uses the load-sensing electronic flow management technology of our M4 or M7 valve and the BODAS RC electronic controller that conveys anticipated load requirements of the working hydraulics to the diesel engine controller in advance of the actual hydraulic load on the engine. This system provides the benefit of interfacing between the functions of the Bosch control units (for engine management) and Rexroth control units (for the drive and working hydraulics). Based on the DHC inputs, the diesel engine delivers the exact amount of torque and power needed by the hydraulics to provide optimum function of the machine at a given engine speed; as a result, diesel consumption drops by up to 20%.
Currently available and advancing generations of mobile electronics make this possible, increasing overall machine performance, enabling engine downsizing, and optimizating the transfer of available energy for use in the function of the machine. For machine functions such as hydraulic implement control, work/travel drives, fan control, and hydraulic power demand management, the BODAS (Bosch Rexroth Design and Application System) mobile electronics platform intelligently combines electronic components and software to boost machine performance and flexibility with reduced available power of the engine.
The fourth 4EE lever is energy system design that consists of utilizing cutting-edge technology, design, simulation, and testing to look at a machine’s energy requirements as a complete system, and designing the system from the ground up to ensure that the energy efficiency is optimized.
One example where Rexroth has made strides using energy system design is in the development of our HVT (hydromechanical variable transmission) platform for wheeled loaders, dumpers, and bulldozers. After analysis and modeling, we combined the advantages of a mechanical travel drive with a torque converter and a hydrostatic travel drive, to create a hybrid travel drive platform that offers fuel savings of up to 25% compared to a conventional transmission.
Intelligence in integration
Implementing this approach in mobile machinery takes two kinds of intelligence: thoughtful engineering, yes, but also the intelligence to create the most efficient interplay of the various machine components to deliver the energy performance envisioned. We are seeing determined deployment of this kind of intelligence by our customers, as they seek to offer the most efficient machines to their customers. There has clearly been a paradigm shift in the mobile applications market, a shift that, with our partners at Robert Bosch, Rexroth has actively sought to drive as a key value proposition for our customers.
We are seeing innovative new solutions at work that elevate the connectivity with machines—the way information is exchanged between diesel engine control and hydraulics control for example, or the way software now plays a greater role throughout all functional elements of a machine.
This weaving of intelligence into the mobile working machine design is, we believe, part of a larger trend across many industries—what some refer to as “Connected Industry” or “Industry 4.0.” Within a very short time, in many manufacturing production processes, we will see rapidly escalating potential for substantial efficiency gains, thanks to advancing sensor technologies and network-capable components with built-in intelligence, where software takes care of a growing number of tasks previously carried out mechanically.
We are already seeing this trend affect how “smart” the mobile machines can become—and that trend will only accelerate into the future. We are committed to helping our customers, both OEMs and end-users, stay at the front of this growth curve in intelligence and integration. And we are already partnering with many of them, leveraging our systematic Rexroth 4EE approach, to help them take advantage of these opportunities.
The contribution of the off-highway industry toward improving energy efficiency and controlling emissions is a winning proposition for all of us, and will help us, ultimately, to create a future we are proud to be part of.
Berend Bracht, President and CEO, Bosch Rexroth Americas, wrote this article for SAE Off-Highway Engineering