Study On The Hydraulic Controlling System Of The EBZ135 Cantilever Roadheader

The cantilever roadheader is the integration including cutting,walking,loading and transporting mechanisms which is used to tunnel the laneways,which is the main product in the underworkings.In the controlling systems of the roadheader, the hydraulic controlling system is one of the core technologies. The characters of the hydraulic controlling system are one of the most important impacting factors affecting the whole roadheader. Therefore studying hydraulic controlling system of the cantilever roadheader has an important significance in promoting the development of China's roadheader.This topic based on introducing the overall characteristics and developing status of the cantilever roadheader analyzes and summarizes the developing status of the hydraulic controlling system.Through analyzing working conditions of the cantilever roadheader, the paper designs the hydraulic controlling system and studies the working principle of the variable pump and multi-way valve of the hydraulic controlling system,and the hydraulic controlling system is the load sensing system(LS) composed of the load-sensing pumps and the load-sensing multi-way valves which are produced by Rexroth.Then the paper studies the working principle and the characteristics of the load sensing system in depth. The load sensing system can sense the requirements of the hydraulic pressure and flow, so it will provide the requisite pressure and flow of the loading.The hydraulic controlling system of the roadheader mainly applied the throttling system, the variable rotational speed system and the current load sensing system from the past to the present.Now the Rexroth reasearches the new technology called LUDV, which has the larger advantages on the flow distribution compared with LS. The paper simulates the three systems and analyzes the three systems through the intuitive curves. The results show that there is the larger throttling and overflow loss of the throttle system, while LS and LUDV systems have great advantages in energy saving. However, the characters of the LS system in the flow distribution are less than the LUDV system.Taking into account the complexity and characteristics of the entire hydraulic system, the paper establishes the simulating models of the simplified running,cutting and the spading circuit system, which is based on establishing,verifying LS valve,pressure shut-off valve,constant power valve and pressure compensated valve. The simulation results can be seen that the system has the advantages of the load-adapted functions just what the principle states from the curves, so the energy can be saved largelier.But there is the inadequate capacity drawbacks of the flow distribution. That is not as good as LUDV system. Therefore, in future the development of the roadheader hydraulic system should be moving towards LUDV system, so it will have the better flow distribution function.The paper studies dynamic characteristics of the system through changing the parameters of the key component-LS valve.The simulation results show that the increase in the spring stiffness and reducing in the spool diameter of the LS valve help to increase the stability of the system, which will provide a theoretical basis for the study of load-sensing control system's dynamic characteristics and designing load-sensing variable pump.