A Novel of Pump Controlled Electric-Hydraulic Steering System for Wheel Loaders

The load sensing steering system, which is generally utilized in traditional wheel loaders, uses the fixed displacement pump to supply the hydraulic oil. However, there are a large overflow and throttling loss during the steering process. In order to improve the energy efficiency, a constant pump driven steering system was proposed. The constant pump was designed to be driven by servo motor, independently and directly used to supply the required flow for the proposed steering system. The steering speed of electric controlled steering wheel was adopted to control the speed of servo motor. Firstly, a co-simulation model of pump controlled electric-hydraulic steering system was established to analyze the feasibility of the steering system. Then, a test prototype of steering system was established to validate its dynamic characteristics. Finally, compared with the traditional load sensing steering system, the characteristics of pump controlled electric-hydraulic steering system were concluded. The results show that, based on the pump controlled electric-hydraulic steering system, the throttling losses can be reduced, the overflow losses can be eliminated during the steering process, and the energy consumption can be decreased by 56%. Apart from that, the shock and fluctuation of pressure can also be reclined, improving the system stability.