Multi-cylinder Engine Fully Variable Valve System Design And Performance Simulation

Traditional engine with gas phase is often fixed to juggle all the conditions, is a kind of compromise on engine performance. In recent years, the rapid development of variable valve timing technology can replace traditional fixed valve timing technology, implement continuous variable valve timing, and then the engine under different conditions can provide the best valve timing and valve lift, the engine intake performance improved.This article will introduce a set of independently developed by our group fully variable hydraulic valve system (FVVS), The mechanism mounted on EQ486 four-cylinder gasoline engine valve train refit the valve-train FVVS experiment prototype. Canceled in the structure of the original machine intake camshaft, by treating with inlet valve fully variable hydraulic control valve driving mechanism set between inlet valve open; And build a test bench for motored FVVS prototype valve movement of oil spills at different phase angles and different motored speed was measured. Using AVL BOOST software engine simulation model was established, based on the original machine data and measured data to explore the intake fully variable FVVS prototype method of controlling the load of the improvement of the prototype of the pump gas loss effect and the influence of the engine fuel economy. The main content of this paper is as follows:To develop fully variable hydraulic valve system (FVVS) assembled on EQ486 original gasoline engines, to replace the original machine inlet camshaft is controlled by FVVS inlet valve open and close. After the completion of the original gasoline engine modification started building motored test bench, the cylinder head from the motor to the engine motored conducted experiments using a laser displacement sensor for direct measurement of engine valves. Experimental results show that FVVS prototype can direct control the valve movement, continuously variable intake late closed angle continuously adjustable within the range of 263 °crank angle. Verify the fully variable valve mechanism can be achieved by a control valve movement law in all working range to adjust the suction cylinder of engineering quality, basically achieved the expected design goals.Using AVL BOOST simulation software to create EQ486 calculation model of gasoline engine, and the reliability and accuracy of the model is verified. Measuring the movement of the valve test measured valve lift data is input into the simulation model was simulated according to different load requirement, the original machine intake valve lift data is also inputted into the simulation model. By BOOST model throttle successively set different thresholds, FVVS prototype models use different intake valve lift curves to control different intake air mass, intake air to meet the same in both modes at the same speed. The change in cylinder pressure under different EIVC was compared. Through calculation results can be obtained:by changing different drainage FVVS prototype phase Angle motion law of the control valve to control the volume, can completely replace the throttle and the control system for the engine load. Final amount for a fixed speed under different filling coefficient under the change of the original machine with FVVS prototype pump gas loss trend is forecasted, can draw FVVS prototype can be replace the throttle by fully variable valve to regulate the work of the engine intake quality, significantly reducing the intake process throttling effect and reducing pumping loss, and the filling volume coefficient decrease the degree of improvement is more obvious.