Study On Stagnation Characteristics Of Power Shift Steering Transmission Hydraulic Valve In Polluted Oil

Integrated transmission of Armed tracked vehicle contains various transmission countershafts,which work under complicate conditions with single lubricating oil source.Therefore,the working environment of buffer shift valve,which is always breakdown,is contaminated severely.In this paper,the study object is buffer shift valve.The models of initial leakage rate of spool valve,time constant and contamination chucking are established.Hydraulic valve contamination deposit leakage characteristic and contamination lock characteristic were studied.The effect of the structure parameters and the oil contamination conditions on the leakage rate and locking force were analyzed.The mathematical models were verified by test.The main constant of this paper are as follows:(1)The traditional flow formula of eccentric annular space was improved.The taper parameter of spool valve was introduced.The model of initial leakage rate of spool valve was established,which reveals the effects of spool valve structure parameters on the initial leakage rate.Based on clearance filtration theory,the forming process of filter cake was analyzed.The time constant model of contamination deposit was established.The effects of oil contamination condition on time constant were analyzed.The sensitivity distribution parameter and the insensitivity distribution parameter of spool valve were studied.(2)Based on the theory of elastic mechanics,particle hardness and deformation are considered.The model of spool valve pollution clamping force is further obtained.In combination with the pollution deposition leakage model,the influence of the clamping force was studied by the structure parameters and oil pollution situation(3)The model was used to analyze the structure of three different spool valves in power shift steering Transmission.The scope of the best fit clearance was obtained by analyzing the relationships among the spool valve taper,the fit clearance,the eccentricity ratio,the initial leakage,the time constant,and the clamping force.The analysis method can be widely used in the design of the valve.(4)A test bench is designed and built to investigate the characteristics of the hydraulic valve.Leakage data under different diameters of the valve core was obtained in different oil pollution levels,which validated the correctness of the model.