Dynamic Performance Research Of Traditional Valve Train Using Hydraulic Tappet

Developments of the valve trains of domestic and foreign engines are introduced. Referencing the cam contour of some model of diesel engine, a computer program for the calculation of the contour of the cam's buffer segment and active section was worked out by using the design theory of the cam contour. The optimized cam lift range was got and was used for dynamic calculation.TYCON software was used to set up valve train's simulation model of single cylinder diesel engine with imported relevant parameters. And then, on the base of dynamic simulation, the valve train's performance figures, such as fullness coefficient, oil film lubrication coefficient and contact pressure between cam and tappet, were analyzed. According to the results, some conclusions were achieved: the valve train works steadily without flying or strong vibrations or the phenomenon of touch between the spring coils; the thickness of the oil film meets the requirement, the cam contact stress is less than the allowable stress. These show that the design of the valve train is rational and its performances can meet requirement.In allusion to vibration and noises of the valve train, a hydraulic tappet was designed instead of original tappet and the simulation model of the optimized valve train was set up. Based on the calculation, after using the hydraulic tappet, the valve train not only has less vibration and noises but the cam contact stress has been improved obviously. In addition, the hydraulic tappet's impacts on the dynamic performances of the valve train were researched.The test rig was set up to test the actual performances of the valve train using a hydraulic tappet. A camshaft seat and a tank were designed to replace the original engine block, the camshaft and oil pump would be driven respectively by an electro-motor.