Axial Flow Automotive Turbocharger

Abstract

Turbocharger “lag” or poor response to engine load changes can be improved by reducing the rotating inertia of the turbocharger turbine, compressor and shaft system. Recently designed, second generation turbochargers all have small diameter, light weight rotating assemblies in an effort to minimize inertia and improve response. An automotive turbocharger with an axial flow turbine rather than a conventional radial inflow turbine is presented here as an alternative method of reducing inertia. The rotating inertia of the axial flow turbine and a centrifugal compressor is about one half that of the same compressor combined with a radial inflow turbine. In steady-state engine dynamometer tests, the same wide-open throttle performance was obtained with both turbochargers. Engine dynamometer transient tests showed that the turbocharger with the axial flow turbine attained full boost 25–40% faster than did the turbocharger with the radial inflow turbine.