Exhaust gas turbochargers for passenger cars

Future requirements will demand that exhaust gas turbochargers combine the following:

  • Reduction in fuel consumption and therefore CO2 savings
  • Low-end torque for a more enjoyable driving experience
  • Compliance with emission standards
  • Outstanding durability
  • Optimal performance indicators

BMTS Technology supplies the right product portfolio to meet all these demands, with every T/C tuned optimally and specifically to the engine.

A family of T/C´s for passenger car diesel engines with power outputs from 35 to 165 kW has been developed. The boost pressure can be regulated via a wastegate or via variable turbine geometry (VTG). 

For passenger car gasoline engines, the product portfolio covers power outputs from 45 to 220 kW. Due to the engines higher thermal loading, wastegate boost pressure regulation is frequently used for gasoline engines. 

Turbocharging

Schematic diagram of traditional single-stage turbocharging with charge air cooler (CAC) variant: gasoline engine without EGR
traditional single-stage turbocharging with charge air cooler (CAC) variant: gasoline engine without EGR

Turbocharging allows a greater air mass to enter the combustion chamber, and more fuel to be utilized. This leads to a greater power output. In comparison with the naturally aspirated engine, turbocharging produces a higher performance yield, while maintaining the same displacement, and increases the engine’s low-end torque.

Conversely, for a specific engine output, the displacement can be reduced, or "downsized." Downsizing reduces fuel consumption and consequently CO² emissions. The reason for the fuel saving is that the engine is operating with a higher brake mean effective pressure (BMEP) in engine map areas with higher specific loads and thus with greater fuel efficiency.

Design of the exhaust gas turbocharger

The exhaust gas turbocharger (T/C) uses the energy from the exhaust gas to increase the air charge into the combustion engine. In contrast to mechanical supercharging, the T/C does not require any mechanical drive power. In a direct comparison, this results in lower fuel consumption. The T/C comprises two flow machines: an exhaust gas turbine that extracts the energy from the exhaust gas and a compressor that compresses the intake air. The exhaust gas T/C comprises several assemblies:

  • Exhaust gas turbine with turbine wheel and turbine housing
  • Compressor with impeller and compressor casing
  • Core unit with rotor and bearing
  • Regulating device for boost pressure (variable turbine geometry (VTG) or wastegate)