280/330 Single-Cylinder Diesel Valve Train Total Design And Simulation

Developments of the valve trains of domestic and foreign I.C. engines are introduced. The theory of the kinematics and dynamics of the valve mechanism is also described in this paper.Referencing the cam contour of the PA6 diesel engine, a computer program for the calculation of the contour of gas distribution cam's buffer segment and active section is worked out by using the kinematic design theory of valve mechanism, and the calculations for a single-cylinder 280/330 diesel engine are carried out. The calculations include cam lift, cam speed, and cam acceleration under two conditions, one is the compound sine parabolic function cam, the other is high power compound polynomial function cam.The author adopts nowadays popular simulating analytical software of working process of I. C. engine to simulate 280/330 diesel engine's working process. Based on calculations, the author investigates the influence regulations on 280/330 diesel engines because of the change of the late closing of the air inlet valve and prior opening of the exhaust valve, and optimizes the gas distribution timing.Three kinds of cams' contour (compound sine parabola cam, match the high power cam, the PA6B diesel engine cam of polynomial) are calculated and analyzed. The results of analysis are as follows:(A) The valve train works steadily without flying or strong vibration or the phenomenon of touch between the spring coils.(B) The thickness of the oil film meets the requirement, the cam contact stress and the valves closed stress are less than theallowable stress.(C) The design of the valve train is satisfactory, and within those three kinds involved cams, the high power compound polynomial function cam is the best choice.The works of this paper show that PA6B diesel engine should follow the cam contour of PA6 diesel engine with same angle in every segment. Although the valve lift of PA6B is bigger than PA6's, the cam lift becomes small with a bigger ratio of the rocking arm, this is of advantage to enhance the working life of cam.