Abstract
A hydraulic excavator (HE) is a typical piece of construction equipment and is widely used in various construction fields. However, the poor energy efficiency of HEs results in serious energy waste and has aroused the attention of researchers. Furthermore, rising fuel prices and increasing stringent waste gas emission legislation sparked demand for ways to improve energy efficiency. Recovering the otherwise wasted boom potential energy of a conventional HE by proper methods offers the potential to improve the fuel efficiency of HEs. In this paper, a mechanical energy recovery system consisting of a pump/motor and a flywheel is presented for HEs using a load sensing system. When the boom moves down, the boom potential energy is converted into mechanical energy by the boom cylinder and the pump/motor to accelerate the flywheel. When needed, the captured energy stored in the flywheel is converted back into a form of pressure energy to directly drive the boom cylinder up without throttling the main valve. In the lifting process, a compound circuit that consists of a throttling control circuit and a displacement control circuit is presented. A control strategy is proposed to optimize the energy recovery and reuse procedure. A 4-t HE is used as a study case to investigate the energy-saving potential of the proposed system. Numeric simulations show that the proposed system, when compared with a conventional load sensing system, can reduce as much as 48.9% energy consumption in a non-loaded cycle of boom lifting and lowering process. As to a fully loaded case, the energy-saving rate is 16.9%. This research indicates the flywheel-based scheme is promising for developing an energy-efficient fluid power system for HEs and reducing energy consumptions.
Highlights
A hydraulic excavator (HE) is a typical piece of construction equipment and is widely used in various construction fields
When the control signal of the boom-up operation and the rotational speed of the flywheel are greater than their thresholds, respectively, the PM starts to provide fluid to reduce the energy required to the engine
Toisverify the energy recovery and reuse of the proposed system, a simulamodel established in AMESim software, as efficiency shown in Figure tion model is established in AMESim software, as shown in
Summary
A hydraulic excavator (HE) is a typical piece of construction equipment and is widely used in various construction fields. Developing more energy-efficient and environmentally friendly construction machinery-related technologies is a key factor for reducing fuel consumption, CO2 production, and pollutants emissions This is of great importance in the case of HEs. For a conventional HE, when the boom goes down, its gravitational potential energy is converted into heat energy through control valves. Quan et al proposed a new electro-hydraulic hybrid driving system consisting of an electrical-mechanical actuator and a hydraulically passive driving system for HEs [10], where a hydraulic accumulator is used to balance the self-weight of the boom Experiments show that this new system can reduce the energy consumption by.
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