The Research On The Impact Of Engine Oils On The Fuel Economyof Passenger Car Engine

The continual growth of car ownership in China makes the energy and environmental problems continuously emerging,and the CO₂ emissions or fuel consumption regulationsare increasingly stringent,which promotesthe automotive OEMs to improve the engine fuel economy and reduce fuel consumption.Compared with the improvement of engine design and new materials processing technology,development of energy-saving engine oils is more realistic and cost savings.In this paper,the main factors of lubricating oil influencing the engine fuel economywereput forward through theanalysis of engine friction and lubrication mechanism.On the ground of this,different formulas of candidate engine oilhad beencompounded to reduce engine friction loss and vehicle fuel consumption.And these candidateoils had beenscreened and validated through the four-ball frictiontest,engine friction torque test and vehicle fuel consumption test.The main research worksof this paperare as follows:（1）The engine lubricating lineswereintroduced and the friction mechanism,lubrication states,andlubrication modelsof four groups of mainfriction pairsin engineunder different conditionswere analyzed.Then the main factors of lubricating oil influencing the engine fuel economywere put forward.And the classification standards,main physical and chemical properties of engine oilswere simply introduced.Thepreparation process of candidate engine oilswere set forth in detail,including the base oils,functional additives,friction modifiersand viscosity index improvers.（2）The friction coefficient of different candidate oilswasmeasuredthrough the four-ball frictiontestin order to preliminarilyscreen thetype and dosage of friction modifiers.The results showed that the friction coefficient ofcandidateoilswith new organic FM2 was the least and the dosage of 1%and 0.5%of FM had a little impact on the friction coefficient.（3）The total engine friction and engine friction withoutcam mechanismusing different candidate oilswere measured by FTT experiments,in order toresearch the influence of different formulationsand properties ofengine oilsunderdifferent conditions on the friction mechanism of engine parts in differentlubricating states and the friction loss improvement rate.The results showed thatthe reductionofviscosity and the optimizationof recipe of functional additives,FM and VII were goodfor the decreaseof engine friction loss in different degrees.In which,the friction reduction rate of the seventh candidate oilwas the best,up to 9.30%.（4）The vehicle fuel consumption tests based on NEDC were carried out aiming at the different candidate engine oils and the test precision andconsistency had been analyzed and controlled in detail.The resultsindicated that the frictionreduction and lower fuel consumption were matched as the test conditions were controlled well.The5.5%engine friction reduction was matched with the 1%improvement ofvehicle fuel consumption,which confirmed the stability and reliability of FTT tests and fuel consumption testsin turn.