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The heavy earth moving machineries (HEMM) like hydraulic excavator play a major role in construction and mining industries. In this context, the energy saving strategies in hydraulic excavator needs to be addressed considering its vital importance. Since the hydraulic excavators are subjected to heavy loads, hence the opportunity to harness the potential gravitational energy (GPE) remains a key area which can be effectively explored in order to minimize the energy consumption in consideration with hydraulic excavator. In the projected system, the potential energy is stored as pressure energy in hydro-pneumatic accumulator. The upward movement of the boom is executed with the help of prime mover during the starting of the first duty cycle. In the latter duty cycles, the stored pressurized energy is utilized together with the prime mover energy capable to execute the upward movement of the boom. The position of the boom cylinder is controlled by using the conventional PID controller using proportional flow control valve (PFCV) and accumulator. The error between the actual position and demand position of the linear actuator is minimized along with attainment of superior controlled performance while utilizing Model Predictive Controller (MPC). The pressurized accumulator with PFCV has been utilized to cater the different position demands. This has been also justified both experimentally and analytically with the error in the permissible range of 2%. It has been observed that the proposed system is 10% more efficient in contrast to the conventional system.

Considering the loss of high throttling loss for open-circuit hydrostatic transmission at present, hydraulic excavation energy saving is important for removing the source of deficiency and protecting the environment. This paper deals with closed circuit gravitational potential energy recovery system (GPERS) based on energy storage element such as an accumulator, along with the generator. An estimated 16% total energy consumption is reduced when a system using accumulator-motor-generator system is used as compared to the simple motor system. The simulation result is carried out with Automation Studio and MATLAB/Simulink. At last, the paper put forward the future development of GPERS.

The work presents a segmented pump-motor control scheme of a closed-loop hydraulic drive used in mining equipment. It analyses the dynamics of the drive through modeling and simulation. The system model integrates a control scheme for modulating the displacement of the pump and the hydro-motor of the hydraulic drive. The model also considers the state-dependent non-linear losses as well as the transient behaviors of the pump and the hydro-motor. The experimental results validate the model for various working conditions of the equipment. The model simulation also analyses the perturbation of critical parameters and control gain on the system's performance for a wide range of operating conditions of the mining equipment. The study performed in this research work will be expedient for the preliminary design and assortment of similar hydraulic drive used in the mobile equipment.

Counter balance valves are used in hydraulic systems to withhold the vertical loads by preventing the free flow of the hydraulic fluid for the safety purpose. But due to this safety feature of the valve, it creates back pressure on the actuator, when the actuation of the cylinder is required in upward direction, to lift the load. This increases the pressure losses across the actuator in the hydraulic system and in turn heat the oil unnecessarily. This, in turn, causes the system to be energy inefficient. But, in today’s competitive world development of energy efficient systems (EES) is an important aspect. In this article, comparison of energy efficient hydraulic system is done using Pilot Operated Counter Balance Valve (POCBV) and Conventional Counter Balance Valve (CCBV) through MATLAB®/Simulink environment. It has been found that POCBV is more energy efficient than CCBV for a particular set of operating conditions. Effects of physical parameters like pilot ratio, spring rate on stability and efficiency used in designing of POCBV are also studied and compared using MATLAB®/Simulink environment. This model is beneficial for hydraulic machine manufacturers engaged in designing of lifting devices in selecting a suitable valve for particular load application and for the designers to design the main components of the valve.