Research On The Mechanism Of Turbocharger’s Axial Friction Reduce Under Exhaust Brake Condition

More and more vehicles have assembled exhaust brake, because of its goodbraking performance and simple structure. With its advantage of increasing the outputof diesel engine and improving emission, the turbocharger has been widely used invehicles. Therefore the exhaust brake and the turbocharger are usually assembled in asame vehicle. Up to now, there is no specialized research result about the effects ofexhaust brake to performance of turbocharger. For these reasons, through researchingthe effects of exhaust brake on turbocharger’s axial thrust and determining reasonableback pressure and switching strategies for different working conditions, importantreference will be provided for improving reliability of the vehicle and prolonging theservice life of the turbocharger. The main innovative points and research work of thispaper are as follows.(1) Studied turbocharger’s performing characteristics when working in exhaustbrake; planned and carried out the test of exhaust brake and turbocharger linkage.Stimulated the condition of exhaust brake in the test by using motor dragging engine.Got different back pressure by controlling butterfly valve’s opening. And measuredimport and export parameters and axial thrust of turbocharger in different conditions.(2) By using the software of CFD, which is widely used in the field of the fluidmachinery, made associated simulating model for the flow filed of entrance, impeller,outlet, backside clearance of turbocharger, and by using the boundary conditions gotfrom the test to calculate, got the axial thrust and its distributions of turbocharger ineach condition.(3) In order to reduce the axial thrust of turbocharger, presented the way ofprolonging the time of transient operation properly, determining the reasonable backpressure according to the tolerance of turbocharger, increasing the backside clearanceof compressor and decrease the backside clearance of turbocharger.