Research On The Energy Consumption Of The High Efficiency Gasoline Engine Based On The4VVAS System

In order to overcome the poor fuel economy of conventional gasoline engineassociated with pumping loss, a multi-cylinder prototype engine with variable valveactuation devices has been developed. The aim is to achieve improved fuel economyby minimizing the pumping loss, lowering the mechanical loss of the VVA devices,and CAI/HCCI type combustion with acceptable emission levels. The main works andconclusions are as follows:In order to realize the load control by means of fully variable valve actuation andhence improved fuel economy, a new cylinder head has been designed andimplemented on a production4-cylinder engine. This has lead to the firstmulti-cylinder engine in China capable of continuous variable intake and exhaustvalve timings and lifts.In order to meet the demand of wider adjust range for the HCCI/SI hybridcombustion, a VVT phaser has been developed which can change the valve timing for100°CA continuously. This VVT phaser is based on the existing VVT phaser but hasbeen redesigned by compromising the force area of the impeller and the VVTresponse speed. The inner seal capability of the VVT phaser and the adjust range ofthe VVT phaser have also been compromised.A test bench for the VVA devices has been set up for validating the actualperformance of the self developed4VVAS system and understanding the control lawand effect factors of the4VVAS system. The stability and response of the VVAsystem both under fixed and variable engine speed have been researched, and also theinconsistent problem of the valves caused by the manufacture and assemble has beenresearched and solved.In order to investigated the energy consumption of the VVA actuator and thedrive power of the VVA system, the electric energy of the VVA actuator and the drivepower of the VVA system changes by the valve lift has been measured.The fuel economy characteristics of three kind of combustion mode including theSI combustion whose load controlled by the throttle and the SI combustion whoseload controlled by the intake valve and the HCCI/SI hybrid combustion whose load controlled by the negative valve overlap strategy have been researched. The pumpingloss, VVA system driving power and also the combustion duration have beenanalyzed under the three different load control mode. The experiment results showthat the fuel consumption can be largely reduced by using valves instead of thethrottle. The drive power of the VVA system is an important reason to reduce the fuelconsumption of the engine which has the equivalent effect with the pumping lossreduction.