Study On Pumping Loss Of None Throttle Gasoline Engine Based On Intake Valve Closed Earlier

The throttle is used in the traditional El engine to control the load. The throttle percentage is small when the engine was working in the low load, at the moment the pumping loss of the engine is high and this results in high fuel consumption. at domestic and overseas, in order to improve fuel economy of the vehicle SI engine in the condition of low and middle load, a lot of work had been paid to the fully variable valve train technology which can be continuously controlled(without throttle)and reduce pumping loss. In the engine with fully variable valve train, the intake air is controlled by closing the intake valve early or decreasing intake valve lift, through this way the engine can be controled without throttle, pumping loss can be reduced and fuel economy can be improved.The engine with fully variable valve train studied in this paper was abtained by fefitting based on a K157FMI SI engine. The fully variable valve train composes of valve train and hydraulic control mechanism. The continuous control of the max valve lift and opening duration of the valve are achieved through the control of liquidity of the hydraulic oil in the hydraulic control mechanism. In this paper, K157FMI engine is used as the experimental prototype, a series of studies on intake progress of engine performance with fully variable valve train was carried out. The main contents include the following:Firstly, the valve movement disciplinarian of the fully variable valve train and the intake performance under kinds of working conditions are measured on the test prototype. The movement rules of valve is obtained through data processing of the signals of LVDT fixed on the valve train. The result of experiment shows that the FVVT can control the laws of valve movements directly:it can change the valve lift from 0 to maximum 7.5mm and make the valve timing change in 260°CA after TDC continuously, so as to make the maximum valve lift, Valve open continuous horns and timing phase fully variable. The intake efficiency was calculated through measuring the intake flow of motored engine with FVVT. Then the relationship between intake efficiency of different valve movement rules and the speeds is obtained. As a consequence, the throttle can be removed and the intake flow can be controlled by the fully variable valve train through the control of valve movement rules.Secondly, in order to simulate the intake performance, the cycle simulation model of prototype and the engine with fully variable valve train are set up with BOOST. The pressure fluctuation in the intake pipe was measured with the pressure sensor. Then the model set up before was corrected by comparing the results between the simulation and the experiment. Then the pressure in the cylinder was simulated using the correctional model. So, the pumping loss of the engine was calculated.Lastly, experimental data and simulation results were analyzed, and the intake performance of prototype and the engine with FVVT was compared.The conclusion was got:the engine with fully variable valve train could make the vaccum in the intake pipe and cylinder decreased and improve the fuel economy by removing the throttle.