Energy-saving and emission reduction has become the theme of the world. The wheel loader has a harsh working environment, complicated working conditions, and drastic changes in load, and the performance of the engine cannot be fully utilized. Therefore, the variable speed transmission of vehicles plays a vital role in improving the efficiency and performance of the vehicle. This paper establishes the general characteristic equations for the input coupling type of hydro-mechanical continuously variable transmission (HMCVT) based on the wheel loader and determines reasonable structural forms for connection of working conditions. It establishes the general efficiency equation for the reasonable structural form for efficiency analysis and presents a method of co-validation of the simulation and test for making the results of efficiency more accurate. Through this method, the transmission performance is more accurately analyzed, which provides an important guiding role and validation for the early design of HMCVT. Eventually, it gets reasonably optimized products and reduces the design cost and cycle.

The relief valve is an important control and overload protection component of the emulsion pumping station. Its performance will affect the overall performance of the emulsion pumping station and the stable and intelligent control of the working surface. However, the research on high pressure and large flow relief valve for mine emulsion pumping station is still inadequate. In order to meet the requirements of emulsion pump station for large flow sensitivity, stability, reliability, and remote intelligent control of overflow valve, this paper uses the digital control method to establish the mathematical model of the relief valve and uses the software such as AMESim to its dynamic characteristics. The simulation results show that the structural parameters such as spool quality, damping hole, and spring stiffness have an effect on the working characteristics of the relief valve. It also provides reference for the intelligent control research of the large flow relief valve for the emulsion pumping station.

In the hydraulic loading system, the performance of digital relief valve plays an important role in the dynamic response of load. However, the research on large-flow emulsion relief valve is still far from perfect. In this paper, digital relief valve is taken as the research object. Based on pilot-operated relief valve, a digital control scheme using a linear stepping motor is adopted to regulate the working pressure of relief valve. The structure of relief valve is analyzed and optimized from the aspects of dynamic and internal flow field characteristics to obtain a good working performance. To obtain its accurate working characteristic, the structural model and digital control system of relief valve are established by AMESim and Simulink, respectively, for electrohydraulic cosimulation. The results show that digital relief valve has a better characteristic of real-time dynamic pressure regulation. Therefore, the digital control system could improve the dynamic performance of relief valve, and the design of digital relief valve structure is reasonable and feasible. The simulation method employed in this paper provides a better theoretical basis and reference for the comprehensive research of digital large-flow emulsion relief valves based on the hydraulic loading system.