The Study On Valve Operation Parameters And Its Control Strategy Of The Continuous Variable Valve Timing And Lift System By Hydraulic Volume Adjustable

The process to remove the burned gases at the end of the power stroke and admit the fresh charge for the next cycle called gas exchange process. The gas exchange process is not only an indispensable part of the engine working process, but also an key factor to determine the engine power and economy performance. To achieve a better gas-exchange effect, the valve does not just open or close at the TDC and the BDC, but there is a certain angle of advance or delay. These angles include Inlet Valve Closes(IVC), Exhaust Valve Opens(EVO), Inlet Valve Opens(IVO) and Exhaust Valve Closes(EVC). Coupled with the Exhaust Valve Lift and Inlet Valve Lift, these six parameters we called Valve Operation Parameters. These six parameters are closely related to the volumetric efficiency, gas exchange loss and flow resistance, basically determine the quality of the gas exchange process. The valve operation parameters that meet the requirements of the actual working conditions of the engine can make the engine get better gas exchange process, greatly improve the engine power,economy performance and reduce emission.The valve operation parameters of traditional valve mechanism is fixed, which the design of the valve operation parameters split the difference between high engine speed and low engine speed, can not guarantee that the gas exchange process is well in the whole operating range. Therefore, my research group puts forward a continuous variable valve timing and lift system by hydraulic volume adjustable, that can realize the valve timing and valve lift independent, continuous adjustment. In this paper, we will study the valve operation parameters and its control strategy of these system.Firstly, the basic principle of the variable valve timing and lift system and the adjustment of the valve operation parameters with these system are discussed,and the mathematical model of the system is established.Secondly, establish the simulation model of the continuous variable valve timing and lift system by hydraulic volume adjustable based on AMESim software, study the regulating characteristics of the valve operation parameters with the system by simulation. Considering regulating characteristics of the valve operation parameters with the system, we proposed a control strategy for the valve operation parameter.Thirdly, the engine simulation model was established based on AMESim software, and the rationality of the proposed control strategy for the valve operation parameters with the system was verified by simulation.Finally, the adjustment performance test of the variable valve timing and lift system is carried out, and the experimental data and the theoretical regulation characteristics are compared and analyzed.