Application Research Of Port Relief Valve In Hydraulic Cylinder Braking Impact

The hydraulic cylinder is the main executive component in the hydraulic system of construction machinery,which can drive the mass load to move quickly.In actual operation,the hydraulic cylinder will stop suddenly at any position due to power failure or reversing.At this time,the low-cost and highly reliable port relief valve can reduce the oil compression of the brake chamber,but the hydraulic system will produce pressure impact,resulting in damage to the seals and oil leakage.Therefore,pressure impact suppression has become an important research content of hydraulic cylinder braking.In this paper,the buffer braking system of the application port relief valve is taken as the research object,the sensitivity analysis method is used to quantify the influence of parameters on the braking pressure impact,combined with the simulation model of the excavator and the pressure impact simulation experiment to verify,get the theoretical basis of optimization,guide the optimization direction,improve the optimization efficiency,and ensure that the hydraulic cylinder braking system has excellent performance.The main contents of the paper are as follows:Firstly,the working principle of the buffer brake system of the hydraulic cylinder is analyzed,and the mathematical models of the port relief valve,pipeline and hydraulic cylinder are established.The dynamic characteristics of the port relief valve and pipeline of the key components are studied to provide a theoretical basis for the performance improvement of the key components of the buffer brake system.Secondly,the simulation model of the hydraulic cylinder braking system of the application port relief valve was built,and the braking characteristics of the high-speed heavy-duty hydraulic cylinder were analyzed when it stopped at any position.The main sensitive parameters affecting the braking pressure impact were obtained by Morris screening method and orthogonal test design.Then,based on the high-precision simulation model of the excavator bucket rod hydraulic cylinder,the pressure impact of braking at any position is simulated,the change of the brake chamber pressure and overflow flow and other parameters are analyzed,and the suppression effect of sensitive parameters on the hydraulic cylinder braking pressure impact is verified.Finally,the pressure impact simulation test bench was built to test the pressure impact experiment,and the braking pressure under different inlet controlled chambers and different relief valve opening pressure was collected to analyze its influence on the system pressure impact,and to verify the correctness of dynamic characteristic sensitivity analysis and parameter sensitivity analysis.