To improve vehicle startability and transient response of turbocharged diesel trucks, their phenomena have been investigated and analyzed in detail and various supercharging systems have been developed and installed on a truck for comparison of their characteristics.
The systems considered were ceramic, variable geometry, variable entry,and air-assisted turbochargers and a combined supercharging system.
The variable entry turbocharger has two turbine scrolls with different nozzle areas and two switching valves to get three different turbine flow capacities.
The combined supercharging system consists of a mechanical supercharger and a turbocharger. These are linked in series. Both work in a low engine speed range, and the turbocharger only works in middle and high engine speed ranges.
Among these systems, the combined supercharging system is the best for improving both vehicle startability and transient response of a truck.
Moreover,transient black smoke and particulate emission with this system have also been reduced to very low levels.