Research On Characteristics Analysis And Optimization Of Excavator Slewing System

The excavator is a multi-purpose earth-rock construction machine,which has multiple functions such as earth-rock excavation and loading,land leveling,slope repair and hoisting.The successful application of the slewing system makes the excavator more flexible,but due to factors such as rotational inertia and frictional drag torque,it is easy to produce pressure shocks during slewing and cause large power loss.Although the traditional rotary hydraulic system can meet the performance requirements at this stage,the system structure is complex and the manufacturing cost is high.Therefore,the research and analysis of the characteristics of the slewing system can be helpful for the upgrading and transformation of the slewing hydraulic system.This article takes the school-enterprise cooperation project "FW080 full hydraulic crawler excavation development"(project number: FW / RD201717)as the research object,and analyzes and optimizes the characteristics of the 8t excavator swing system.The hydraulic system of this excavator adopts Rexroth's A11 VO variable pump,which is a power control with pressure cut-off and load sensing.By studying the excavator's slewing motion,the factors affecting the slewing characteristics are determined.Through the combination of simulation modeling and real vehicle test,the effects of the rotating torque,friction torque,rated pressure of the rotating hydraulic system and the rotating angle on the starting and braking characteristics of the excavator are analyzed.In view of the above analysis and the shortcomings of the rotary hydraulic system,an independent regulation system for the flow of inlet and outlet for large inertial loads is proposed.Build a simulation model and study its slewing characteristics to provide a reference for the upgrading and transformation of the slewing hydraulic system.The research content of this article is mainly composed of the following parts:(1)This article outlines the composition of the excavator slewing system and the classification of its hydraulic system,as well as the current energy-saving technology applied to the excavator,which provides a reference for the research content and research direction of this article.(2)Based on the introduction of the working principle and system composition of the rotary hydraulic system,the working conditions of the rotary hydraulic system under various typical working conditions are analyzed,and the static and dynamic characteristics of the rotary hydraulic system are obtained.Analytical calculations of key parameters affecting the turning characteristics have laid a solid foundation for the theoretical analysis of the full text.(3)The AMESim hydraulic simulation software is used to establish the slewing hydraulic system simulation model,and the ADAMS dynamic simulation platform is used to establish the joint simulation model.By setting two specific postures of the excavator working device,the simulation is performed under the same rotation angle,and the experimental results under the same conditions are compared and analyzed.The analysis results show that the simulation model is correct.(4)The simulation model was used to analyze the effects of rotational inertia,frictional resistance torque and slewing system pressure on the starting and braking characteristics of the slewing hydraulic system.Clarify the degree of influence of various factors on the rotation characteristics and the energy consumption characteristics of the rotation process.(5)The traditional rotary hydraulic system has only one input control variable,the displacement of the spool of the multi-way valve,which causes the system to generate large energy losses due to excessively high rotary pressure during the rotary braking phase.This paper proposes an independent adjustment scheme for inlet and outlet: replace the rotary control valve with four two-position two-way electromagnetic proportional valves,use two two-position three-position directional valves to feedback the load pressure,and between the inlet and outlet of the rotary motor Install the accumulator.The simulation model is changed according to the proposed scheme,and the simulation under the same working condition is carried out under the condition that the load remains unchanged.The analysis results show that the slewing system adds multiple degrees of freedom,the new scheme has a smoother slewing process,and it takes less time to rotate the same slewing angle,reducing the impact and jitter generated by the excavator slewing platform during the slewing startup and braking process.