An Energy-Saving Scheme to Reduce Throttling Losses in Hydraulic Excavators Based on Electro-Hydraulic Energy Storage

The enormous throttling losses are the crucial reason for the low energy efficiency of non-road mobile machinery. To achieve energy saving, a parallel electro-hydraulic hybrid drivetrain that combines an electric-hydraulic energy recovery system with a valve-controlled system is proposed. With a parallel electric-hydraulic energy recovery system, both the energy lost caused by load imbalances and overrunning loads can be recovered and reutilized. To achieve satisfactory operation performance and minimize energy consumption, a rule-based energy management strategy is implemented for real-time control. Several experiments are conducted to verify the feasibility and energy-saving features of the proposed scheme. Additionally, taking a 37-ton hydraulic excavator as an example, a co-simulation platform is established to demonstrate its working characteristics under various conditions. Compared with the hydraulic excavator without energy recovery, throttling losses and energy consumption of the proposed system are reduced by 60%-75% and 24%-27%. Moreover, the proposed system integrates the energy-saving pressure compensator, and the response lag between the heavy-load actuator and light-load actuator is shortened by 47% during multi-actuator motion, effectively improving coordination and maneuverability.