Pneumatic linear drives are widely used in manufacturing, mainly for handling tasks. Due to rising interest in environmental matters and increasing energy costs, energy efficiency has become a major issue in industrial applications. There is a growing competition between pneumatic and electromechanical drives. Pneumatic drives are said to have a lower efficiency while the initial costs of electromechanical drives are higher. The operating costs of electromechanical as well as pneumatic drives are induced by their exergy efficiency. The efficiency of the drives depends on parameters like cycle time, load applied to the cylinder and its acceleration and velocity. Former research did only provide limited data on the influence of these parameters. The paper provides an overview on the exergy efficiency of pneumatic and electromechanical drives and its dependency on the mentioned parameters. Since electromechanical drives are often used to replace pneumatic drives both technologies are examined in typical applications for pneumatic drives, including horizontal and vertical movement and sustaining a load for different periods in vertical usage.

Today the selection of drive technology for realizing of moving tasks is made by comparing of investment and energy costs in general. Pneumatic drives are characterized by their low purchase price, but at the same time they show high energy consumption in a comparison with electric drives. This general evaluation leads to the point, that in many cases the optimum drive structure for a certain handling task can’t be found regarding functionality and efficiency. To reach that goal, the dynamic, energy and costs characteristics of the actuator have to be observed and summarized. In this paper the EXonomy analysis is presented as a base for the inter-domain comparison of electric and pneumatic drives. Developed EXonomy approach enables the objective analysis and comparison of electric and pneumatic systems within 3 steps.

This paper describes a new application for servopneumatic drives. In a battery module for automotive applications the pouch cells are clamped between frames. During the assembly the frames needs to be clamped permanently. So a clamping system comprising two drives was developed, which moves four clamp fingers each alternating. In the first chapter the application is described in detail. The second chapter includes a comparison of servoelectric and servopneumatic drives for this application with respect to energy consumption, installation space and purchase cost. The developed clamping unit is described in chapter three as well as a verification of the influence of the preload force on the straightness of the stack. At the end of this paper the conclusions are summed up.

During the past three years the Institute for Fluid Power Drives and Controls in Aachen has developed a new hydraulic system for mobile machinery called STEAM. The system represents a new step in excavator hydraulics, as it aims to reduce both the hydraulic system losses as well as those of the internal combustion engine by using a hybrid hydraulic architecture with accumulators. Starting with initial simulation studies the development has been followed by scaled test bench measurements and has progressed to a full scale validation using an 18 t excavator. The following publication aims to summarise the results obtained thus far with the aim of making them available to industry and encouraging their implementation in future applications.

Environmental awareness, production costs and operating expenses have provided a large incentive for the investigation of novel and more efficient fluid power technologies for decades. In the earth-moving sector, hydraulic hybrids have emerged as a highly efficient and affordable choice for the next generation hydraulic systems. Displacementcontrolled (DC) actuation has demonstrated that, when coupled with hydraulic hybrids, the engine power can be downsized by up to 50% leading to substantial savings. This concept has been realized by the authors‘ group on an excavator prototype where a secondary-controlled hydraulic hybrid drive was implemented on the swing. Actuatorlevel controls have been formulated by the authors‘ group but the challenge remains to effectively manage the system on the supervisory-level. In this paper, a power management controller is proposed to minimize fuel consumption while taking into account performance. The algorithm, a feedforward and cost-function combination considers operator commands, the DC actuators‘ power consumption and the power available from the engine and hydraulic hybrid as metrics. The developed strategy brings the technology closer to the predicted savings while achieving superior operability.

This paper is presenting the application of Power Regenerative Boom(PRB) system to excavator. In order to increase the fuel efficiency of the excavator, potential energy of the front structure is recuperated by the hydraulic hybrid system with electric-hydraulic control, during boom down motion. Charged energy into accumulator is reused after boom down motion, the pressurized oil goes to hydraulic motor. The hydraulic motor is mounted on the engine PTO(Power Take-Off), therefore output torque of the hydraulic motor assists the diesel engine directy, it leads to decrease fuel consumption of diesel engine. After the system design and simulation investigation, the presented system was installed into Doosan’s 38ton excavator, DX380LC-3 model, and the energy saving result was verified by a digging and dumping repetition test. The test result shows that fuel consumption was dramatically decreased by 5.0 L/hr compared to the standard DX380LC-3.

Energy saving and fuel consumption reduction techniques are among the principal interests for both academic institutions and industries, in particular, system optimization and hybridization. This paper presents a new hydraulic hybrid system layout for mobile machinery implemented on a middle size excavator. The hybridization procedure took advantage of a dynamic programming (DP) algorithm, which was also utilized for the hybrid components dimensioning and control strategy definition. A dedicated experimental activity on test bench was performed on the main components of the energy recovery system (ERS). The JCMAS working cycle was considered as the reference test for a fuel consumption comparison between the standard and the hybrid excavator. A fuel saving up to 8% on the JCMAS cycle, and up to 11% during the digging cycle, has been allowed by the proposed hybrid system.

Liebherr mobile harbor cranes use electrical generators to provide electrical power for load attachment devices such as container spreaders or magnets. Upcoming exhaust and noise emission standards and energy saving considerations lead to a broad diesel engine speed range. The challenging design aspect is to ensure a constant speed of the asynchronous generator by the hydraulic drive system. In addition, electrical load profiles of inductive consumers usually have DT1 system characteristics with very small time constants. They evoke fast torque variations interfacing the hydraulic transmission. Liebherr mobile harbor cranes, see Figure 1, usually have a closed hydraulic circuit containing a hydraulic pump with a high displacement volume that is adjusted electronically in accordance to the current diesel engine speed. Regarding the energy saving aspects, a further minimization of the diesel engine speed leads to a larger pump size with increasing torque losses. Depending on the pressure setting, the volume flows can be reduced in constant pressure grids. Especially in part-load operation this results in better efficiency compared to closed hydraulic circuits by minimizing the displacement volume of hydraulic components. To obtain a stable generator speed, it is essential to adjust the displacement volume of the hydraulic unit for equalizing its input torque with the Figure 1: LHM 800 Group 10 - Mobile Hydraulics | Paper 10-5 199 generator load torque. In interaction with the software-based control architecture, the stability of the electrical frequency depends on the mass inertia of the generator drive and time constants of the embedded hydraulic actuators. The system model, represented by ODEs is established and verified with a hydraulic simulation software. On that basis, the design approach of a PI-state-controller is presented. Corresponding controller gains and state feedback parameters are determined by pole placement techniques. To conclude this investigation a comparison between the hydraulically closed circuit and the constant pressure grid is shown by simulation and measurement data.

Presently, there is a four-year window to prepare engines for upcoming TIER V regulations through solutions for peak power shaving and downsizing of diesel engines. In particular, Non-road mobile machinery(NRMM) offer a promising and challenging field of application due to their duty cycles, which includes high and short power peaks and extreme working conditions. In this paper, a series hybrid electric powertrain for a mining loader is presented with the goal of reducing the fuel consumption. A full-scale mining loader powertrain prototype was built to exploit the benefits of a series hybrid electric powertrain at low traction requirements with a combination of decentralized e.g. zonal hydraulics. Corespondingly, this paper introduces the structure of the mining loader and initial mathematical model of the system of a Direct Driven hydraulics (DDH). In this research, an experimental test was conducted, and the initial results are presented in this paper.

The paper presents design solution and physical implementation of a system for examination of electro hydraulic steering based on OSPE 200 components. The implementation is based on synthesis of required hydraulic and structure parameters, presented in a previous paper. Now we present the interconnection of the digital control system and the closed-loop flow diagram. A formal description of embedded software is presented too, which supports operation of PI control algorithm in real-time. Identification is performed based on experimentally reported the transitional process by developing mathematical models. Presents the structure and capabilities of the models for identification, as well as procedures for their validation.