Chen J., Wang Z., Tian F., 2016, A New Hydraulic Variable Valve Timing and Lift System for Spark Ignition Engine, Chemical Engineering Transactions, 51, 1249-1254.
A continuous variable valve timing and lift system by hydraulic volume adjustable (CVVTL) for both intake and exhaust valves of Spark Ignition (SI) engine is introduced in this paper. Unlike existing hydraulic variable valve systems, the CVVTL does not use the electro-hydraulic valves. A four-cylinder CVVTL prototype of engine cylinder head was built, and the valve movement laws of the prototype were tested. The experimental results show that the CVVTL can achieve fully variable valve timing and lift adjustment according to the engine speeds. An AVL Boost simulation model is built to simulate the performances of baseline engine and CVVTL engine. The simulation results show that the CVVTL engine has uplifted improvement in the power, torque, volumetric efficiency and brake specific fuel consumption (BSFC) compared to the baseline engine at different engine speeds, particularly at the low and medium speeds. Experimental and simulation results show that the CVVTL has the potential to eliminate the traditional throttle valve in the gasoline engines.
