Exhaust emission regulation has become stricter year by year because of the global movements of environment protection. In consequence, turbocharger application to diesel engines became indispensable. Especially a variable geometry turbocharger (VGT) is perceived as the essential item.
Of late years, the diesel engine has a trend of higher exhaust temperature to increase specific output. At the same time, needs of the turbocharger application to the gasoline engine has been rising again in order to reduce the size. In spite of this trend of the emission temperature increment, VGT of the variable nozzle vane type which is commonly available in the current market has problems of high temperature resistance due to its complex structure. AISIN SEIKI has developed a variable flow turbocharger (VFT), which is able to resolve those problems.
Although we found it quite difficult to develop VFT because of its uniqueness, our continuous development enabled it to reach the level of volume production.
This paper describes the following items in the development toward VFT volume production, which are:
Optimization of stationary vane geometry by utilizing CFD
New turbine structure with special precision manufacturing method applied to vane
Result of comparative test between the latest VFT and VGT in other methods by using test rig and engine