Research On Key Technology Of Three Action Electric Pump With Single Piston Of Heavy Truck

Electric pump of heavy truck is widely used in lifting hydraulic system of heavy truck’s cab because of its simple structure,easy to use and so on,but there are some shortcomings such as high rotating speed,large impact and vibration,large recoil flow and low volumetric efficiency in high-pressured single piston pump with eccentric wheel structure used at present.Therefore,in the paper,a kind of technical scheme based on three acting high-pressured electric pump of heavy truck equipped with cam mechanism is put forward,and the pump was studied comprehensively by the combination of theoretical analysis,structural design and virtual simulation,which provide theoretical support and technical reference for the practical application of new products,and have a certain value of engineering application and theoretical research.First of all,research on the design of the general plan and the cam profile.In the paper,a kind of technical scheme based on three acting electric pump of heavy truck equipped with cam mechanism and check valve is put forward by the design and compare of three kinds of common cam profile.Then the reasons of producing jumping and flutter phenomenon was ascertained by the analysis of the kinematics of the piston.The results show that the designed cam profile meet the requirements of the project completely,and the cause of the jump and flutter is due to the unreasonable design of the locking spring stiffness.Next,research on the mechanical characteristics of piston and the design of locking spring stiffness.The locking spring stiffness was designed by establishing the mechanical model of the plunger in the oil-absorbing stroke and combining with the conditions of no jump and flutter.And then the effect of various parameters on normal pressure and contact stress between cam and plunger,positive pressure and friction between cylinder bore and plunger was explored,and the contact fatigue strength between the cam and plunger was checked by establishing the mechanical model of the plunger in the pressure stroke.The results show that the design method of the locking spring stiffness is correct and feasible,and the contact fatigue strength of the cam pair can fully meet the requirements.Once again,research on the leakage characteristics of piston pair.The leakage characteristics of piston pair clearance were studied by establishing its mathematical model of leakage,and piston pair clearance,minimum cylinder length,piston diameter,pressure and rotational speed were discussed in detail to analyze the effects on the leakage,and obtained the corresponding structural parameters of piston pair.Then the leakage flow field in the plunger vice slot is simulated by the CFD method,and the influence of inclination on the leakage and the distribution of fluid pressure and velocity in the plunger gap is explored in detail.The simulation shows that with the increase of the inclination,the pressure and velocity distribution of the flow field are not uniform,and the leakage of the piston pair increases gradually.Finally,research on the design of check valve and its flow characteristics.The check valve was designed combining with the performance requirements of the pump.Then the flow characteristics of the pump were studied by establishing the simulation model of electric pump of heavy truck and hydraulic system,and clearance volume,spool mass,spring stiffness,spring preload,maximum opening of spool,inhalation vacuum and rotational speed were discussed in detail to analyze the effects on the flow characteristics,and put forward the corresponding improvement plan,which provide the basis and theoretical reference for the design optimization and manufacture of the pump.The results show that the improved design method of the check valve is correct and feasible,which can effectively reduce the backflushing flow and improve the pump’s volume efficiency.