Dual-variable control load-sensing system for multi-way valves in hilly and mountainous tractors

To tackle the challenges of severe pressure loss, mismatched flow supply and demand, and high flow demands at pump outlets commonly seen in multi-way valves of hilly and mountainous tractors, a load-independent flow distribution system was developed. This system combines an electro-hydraulic load-sensing pump with an independent flow distribution mechanism at the load port, resulting in a dual-variable load sensing system that integrates variable displacement and variable speed control. Using AMESim software, the core components and system model of the dual-variable load sensing system were built. Considering the operational characteristics of the multi-way valve, a load-sensitive variable pump with pressure differential and displacement detection was employed as the feedback control unit. The system incorporates a valve post-compensation mechanism and a three-position, six-way electro-hydraulic proportional directional valve. Additionally, a self-adjusting motor control method for pressure differential adaptation was introduced to regulate system pressure under high-load conditions. Simulation analyses of the system performance revealed that the design effectively boosts energy efficiency, achieving average energy savings of 20% and reaching up to 50% under optimal conditions, while keeping pressure fluctuations at the valve port within a 5% margin. By employing dual-variable load sensing technology, this system substantially improves the energy efficiency and operational effectiveness of multi-way valves while maintaining stable pressure throughout the operation. The design offers a reliable technical framework for the development and optimization of multi-way valves in hilly and mountainous tractors.