Analysis And Research Of The Valve Train System Of The Design And Development Of Euro V Diesel Engine

As one of the two large mechanisms of internal combustion engine, thevalve-train control valves opening and closing in accordance with certain rules, and toensure the well of gas exchange, high charging efficiency with the cylinder, low pumploss, to make sure the engine has good power and economy, meanwhile make thevalve train to work steady, reliable and low noisy. Therefore, with the enginedevelopment to be miniaturized, low emissions and low fuel consumption, to developthe modern valve train seems to be of great significance.The article research a benchmark engine of Euro IV supercharged and intercool-ed diesel engine’s valve train, establish the kinematics and dynamics model of therelevant valve train by AVL EXCITE TD, analysis the dynamic characteristics of theengine’s cam profiles, using high-order equations to optimize the original type line,and finally through the AVL BOOST software comparative analysis of the externalcharacteristics of the optimization program and the original program.The Dynamic Simulation results show that:（1） The workbench’s single valve kinematics results show that the contact stressof cam and rocker arm roller is small, there is no valve resonance phenomenon, butlow fullness coefficient, from the point of view of the intake air charging efficiency ispoor, and founding in the high-speed segment the exhaust valves’ seating velocitygreater than0.5m/s, the valve seat wear grievously. In addition the absolute value ofnegative radius of curvature of the intake cam is less than the recommended value of80mm, which will make difficulty to the supplier of cam machining. It need tooptimize the local buffer segment and segment of the intake and exhaust cam line.（2） Respectively using of two kinds of optimization solutions to optimize theoriginal type line, the optimization results show that, not only to ensure the betterdynamic performance of the original type line, the single valve Department of intakeand exhaust cam fullness coefficient must increase to about0.5, and the otherkinematic evaluation showed to be well, the single valves Department of the valveseated speed less than0.5m/s, but the result of the operation of the multi-valvesystem that approached the exhaust valves in the high-speed section was closed to0.8m/s. Through adjustment of the valve clearance, it is found that the clearance of theintake valve is0.25mm, and the exhaust valve’s clearance is0.4mm, the valve seatingvelocity is less than the allowable value. （3） Through the analysis of the one-dimensional thermal simulation, the resultsshow that and optimization of cam profiles’ external characteristics of power, torque,fuel consumption in the low-speed range （800rpm²000rpm） is better than theoriginal cam profiles, but in the high-speed segment （≥rated speed of3200rpm）three programs draw to be nearly.（4） Determine to select scheme ii for the development, preliminary test resultsshow that the rated speed （3200rpm） corresponding effective output power close to110kW of the design index, torque closed to360N·m, external characteristicminimum fuel consumption for206g.（kW.h）^-11, excess air coefficient λ keep in1.2¹.8, and in high speed conditions kept in near1.8.The work of this article accumulation the technical foundation for thedevelopment and design of Euro V diesel engine valve train for the school-enterprisecooperation, the design of diesel engine will be the main driving force of theenterprise in the next a few years.