Experimental Studies On Close Loop Control Strategy For Fully Variable Valve Actuation

Currently, energy consumption and environment pollution are two main problems for automotive industry. Thus, low fuel consumption, low emission, high torque and high power output is the objective of automotive engine. Among numerous advanced technologies, Variable Valve Actuation (VVA) is considered as one of the most efficient way to improve gasoline engines'fuel consumption, increase power output and reduce emissions. Furthermore, VVA is also regarded as one of the most efficient way to realize new generation combustion theory - Homogenous Charge Compression Ignition in gasoline engines.This dissertation mainly focused on the control strategy for VVA. After a detailed introduction and analysis, the significance for the development of VVA was pointed out. In order to do the research about control strategy for VVA, an experimental system based on a typical mechanical fully variable valve train was built up. The experimental system includes research platform, ECU and experimental management interface.For Variable Valve Lift (VVL) system, classical PID control arithmetic was adopted as the main control strategy. For Variable Valve Timing (VVT) system, a kind of self-learning control method was proposed. According to the experiment, the control strategy was amended detailedly. As a result, a fast, precise and steady dynamic result as well as a reliable static state was achieved.The effect of operating parameters on VVA's control property also was studied. Experimental results showed that operating parameters didn't have much prominent effect on VVL system. Engine speed, hydraulic oil's pressure and temperature affected the VVT system's control process diversely.In the end, the control strategy of VVA was applied in a 4V cylinder head and experimental results proved its good adaptability. CAI engine's operation experiment showed that the strategy for VVA could control the valve's lift and timing well. As a result, the VVA could fulfill the basic control requirements of CAI engine's operation.