Improve The Design. Wd618.44 Diesel Engine Valve Train

The valve train system is one of the most important mechanisms in a diesel engine. If the diesel engine has a superior economic performance, a dependable work, and if the noise and the vibration can be controlled in a lower limit, which usually depends upon its valve train system. Along with the requests of the diesel engine's high power, super-speed, people demand a higher performance index. That is, when the diesel engine runs under a high speed, it can still work steadily and dependably, which demands that the valve train system should have a higher performance.WD618.44 diesel engine's original valve train system exits certain problems, the main problems are: the cam wear is very serious, the phenomenon of vibration, and loud noise. In order to improve the performance of WD618.44 diesel engine, an improving design has been made for its valve train system. The main works are as follows:(1) By using method of least squares, the curve fitting was done to the intake and exhaust cam profile, and the calculation formula of the lift, the speed and the acceleration of each curve were got. Therefore, the dynamic calculation and size-chain calculation of valve train system in WD618.44 diesel engine can be done based on these formulae.(2) One kind of single freedom mass-spring dynamic model of the valve train system was established, and the dynamic calculation was made by using Runge-Kutta method.By analyzing the calculation results, we discovered that the original exhaust cam profile exited such faults as flying to take off phenomenon, large contact force and the acceleration have to chop round the point, which resulted in the conflicts between the cam and the pole, cam wear and tear, loud noise and undependable work.(3) In order to analyze the clearance between the piston and the valve, the size-chain calculation was made by using statistics method while WD618.44 diesel engine was at static state and dynamic state separately.(4) To solve the problems existed in the original valve train of WD618.44 diesel engine, a new exhaust cam profile was designed.The experiment verifies that the new cam has better performance than the original cam. The improving WD618.44 diesel engine's performance index can meet with the related standards, and it has passed the full speed and whole enduring tests. After putting it into use, the effect is very good and it has gained an excellent economic benefit for the enterprise.