Structure Modification And Investigation Into Performance Of Orifice On Multiple Valve For Hydraulic Excavator

The multiple valve of hydraulic excavator is the primary hydraulic control element of hydraulic system on hydraulic excavator, which primarily controls the motion of machines. Currently, few people do the research about it home, and the level of production process is not high, which seriously block the process of its native production. The thesis analyses the multiple valve of small hydraulic excavator, based on the real project. The structure of multiple valve is modified in order to simple machine process and improve the machine efficiency on condition that the modification could meet the requirement of using performance, which can boost its native production.In this thesis, theoretical analysis and numerical simulation are used to investigate the controlling performance of multiple valve. It broadens the width of notch and relatively changes the depth of notch in order to keep the flow area unchangable, which lagely simples the machine process, and improves the machine efficiency of all the notches on the multiple valve. Through numerical calculation, the pressure graph, velocity graph, flow force and so on of all the notches of rotation block on the multiple valve which is designed and modified is basically identical with the old one. And the performance of the multiple valve modified is not changed, compared to the old one, thus the rotation hydraulic system has good control performance, good operator comfort and some energy-saving effect.The main content of this thesis:In chapter 1,The history and current research progress on hydraulic system and multiple valve of hydraulic excavator are reviewed. Lastly,the main research subjects are presented.In chapter 2, The work principle and character of all the hydraulic system circuits of hydraulic excavator is analysed such as boom, arm, bucket, rotation, travel, dozer and so on.In chapter 3,The thesis introduces the method and principle on calculation of orifice area on multiple valve of hydraulic excavator,leads to the equation of gradually-expanded U orifice area which is machined by vertical milling tools, and analyses the orifice area under the situation of translatory motion of valve core for multiple valve.In chapter 4, The interior flow character of the old multiple valve and the new one is respectively analysed. The pressure graph, velocity graph, flow force and so on of all the notches of rotation block on the multiple valve which is designed and modified is basically identical with the old one.In chapter 5,The old and new rotataion hydraulic system of excavator is respectively analysed through AMESim software, and the result of simulation presents that The input and output pressure, output flow, output torque and so on of the new multiple valve which is designed and modified is basically identical with the old one.At the end, this paper analyses the performance of the old and new valve,and looks forwards to the next step of research that the modified multiple valve should be tested,and it should try to modify other blocks of multiple valve in order to simple machine process and improve machine efficiency.