Turbocharging is a common and simple method to utilize the exhaust heat of an
internal combustion engine. However, conventional turbocharging exhibits the
drawback of exhaust gas backpressure and thus increased residual gas mass in the
cylinder.
A promising concept to increase optimum efficiency is found in the TwinAV
concept, which assigns divided exhaust valve cam timing and exhaust manifold
configuration. This concept is hypothesized to reduce the static backpressure in
the gas exchange loop and the residual exhaust gas amount in the gas exchange
phase.
In this article, a 1D simulation model was adapted to an existing 4-cylinder
gasoline TC engine. Subsequently, the engine concept was applied to this engine
model, whereas the focus was to achieve an engine layout for the entire engine
speed range applicable for use in passenger vehicles. The results were compared
at the full RPM range. Also, a load variation was conducted and benchmarked.
The found results show an additional specific fuel consumption benefit of 6.4%,
which is partly achieved by the reduced static backpressure and partly a result
of less knock sensitivity due to less remaining internal EGR, observed in an
earlier CA50 and peak pressure position. Simulation results indicate benefits in
the upper half of the engine map and a maximum benefit in a region around the
engines’ sweet point. This is a conceptual simulation-based study; no
experimental or transient validation has been conducted.
