Twin scroll turbine technology
When optimizing engine performance with the objective of minimizing fuel consumption and engine emissions, ideally this should be achieved without a penalty in engine responsiveness. From this perspective, a swift and highly dynamic turbocharger performance over a large engine operating range is preferred for downsized engines. Among others, such a turbocharger performance can be achieved through the application of multiple-entry turbine concepts. When applying a multi-entry turbine, one can maximize the potential of the pulse energy present within engine exhaust gas. By doing so, not only stationary but also transient turbine performance is improved. This will result in a more reactive turbocharger with a minimum response time or so-called ‘turbo lag’.
One of the technologies which can be applied for this purpose is twin scroll technology.
The twin scroll turbine design is characterized by a volute that is divided meridionally by a wall with two parallel inlets. Each inlet is feeding the nozzle-less turbine through the entire rotor circumference.
The divided volute itself is fed through an engine exhaust manifold which has separated volumes. In this configuration, the pulse dampening and interaction is minimized thereby maximizing the utilization of pulse energy for improved transient engine performance while minimizing engine pumping losses.
Twin scroll turbochargers are commonly applied on high-end gasoline engines with an emphasis on ‘low-end’ performance, i.e. providing relatively high engine torque at lower engine speed. In particular, this technology is advantageous for combustion engines with four or more cylinders while normally, these engines are characterized with significant pulse overlap. The typical engine displacement range of these engines is about 1.5 till 2.5 liters. For larger displacement engines, or engines with more than 4-6 cylinders, it may be more beneficial to apply multiple turbocharger configurations like ‘twin turbo’ concepts.
As a major TIER1 supplier we can provide twin scroll technology in any desired range. We have a lot of knowledge and gained much experience in designing, developing and producing OEM twin scroll turbocharger systems with integrated exhaust manifolds in particular for 2 liter displacement downsized gasoline engines. Our twin scroll technology was for example successfully applied to the BMW B48 engine. Our twin scroll technology turbochargers are able to operate at very high turbine inlet temperatures (up to 1050 ⁰C) and are optimized for system performance, e.g. interaction with downstream catalysts.