Research On Cam Mechanism Of Hydraulic Volume-adjustable Continuous Full Variable Valve System

Valve mechanism as an important part of the engine, its performance will have a significant impact on the economy of the engine, emission and dynamic. Conventional engines Valve uses a compromise gas distribution program, which can not take into account gas intake performance of both the high speed and low speed.There are some limitations in the existing variable valve mechanism, valve timing and valve lift can not be achieved in accordance with the best match engine operating conditions, and the practical application did not reach the ideal state. To solve these problems, the studying team proposed the continuous variable valve timing and lift system by hydraulic volume adjustable. Cam mechanism as the driving unit of the system, it plays a key role in normal operation of the system. Therefore, this article mainly analyses the cam mechanism of the continuous variable valve timing and lift system by hydraulic volume adjustable.First of all, the structure, phase adjustment mechanism and lift adjustment mechanism of the continuous variable valve timing and lift system by hydraulic volume adjustable are analyzed, and the characteristics of its the cam and the factors affecting the motion of the system are analyzed.Secondly, according to the requirement of the continuous variable valve timing and lift system by hydraulic volume adjustable to the cam, the cam profile which can satisfy the working performance of the system is designed from the aspects of reducing the impact,improving the kinematics and dynamics characteristics. To reduce the rigid impact suffered follower of cam mechanism that passed the convergence point cam base circle and cam working line,the author put forward the viewpoint of the convergence of the section of the sinusoidal line and the constant velocity line,and the transformation of rigid impact to flexible impact is achieved theoretically, and the force condition of the cam was improved.Thirdly, the characteristics of the media driven by cam mechanism were analyzed, the influence of the compressibility of the medium and the leakage of the medium on the valve lift, advance angle and lag angle are summarized. To reduce the impact of the characteristics of the media on the movement of the valve, the modifications are made for theoretical design of cam profile.Finally, the simulation of the movement of the valve was implemented, and the modified cam was assembled on physical prototypes developed by the studying team to experimentize. The results showed that the valve lift curve of experiment and the valve liftcurve of simulation on the trend remained were same. Rationality of the design of the cam has been verified.