Hydraulic Accumulators as Key Components in Energy Efficient Mobile Systems

摘要

In the development of more energy efficient machineries the hydraulic system design and the fluid properties are of great importance. For hydraulically driven machines, operating in a cyclic manner the energy consumption can be considerably reduced, by using hydraulic accumulators as energy storage devices. In the design of a system equipped with a hydraulic accumulator there are two important aspects to consider. One is how the system performs from the energy point of view. Secondly, to get really good use of the accumulator the designer has to consider how it will affect the need of power supply. By using the accumulator as an energy storing devise, where some of the potential energy can be reused, it is possible to design a system with improved endurance compared with a similar one without such a system. The reduced energy consumption of the hydraulic system will affect not only the performance but also the environment in a favorable way. To get full advantage of the accumulator the designer should not only focus on the energy consumption. Since the accumulator adds a higher power supply capability, the system should also be optimized in terms of the need of power. Optimizing the system in this way will give the designer a couple of new alternatives. The additional power can be used to increase the performance of the system, without increasing the power from the existing hydraulic supply units. Another choice would of course be to use this power to reduce the size of the other components. The aim of this paper is to show how a hydraulic accumulator can be used in mobile hydraulic systems in order to reduce energy consumption and achieve increased performances. The amount of saved energy and need of supply power is determined by simulation and optimization. The importance of laboratory tests to verify the simulation model for the system is denoted. The main result of this work is that the most important design parameters for accumulator system have been examined and quantified in a way that they can become useful for further system development.