Downspeeding a Light Duty Diesel Passenger Car with a Combined Supercharger and Turbocharger Boosting System to Improve Vehicle Drive Cycle Fuel Economy 2013-01-0932
Downsizing and downspeeding have become accepted strategies to
reduce fuel consumption and criteria pollutants for automotive
engines. Engine boosting is required to increase specific power
density in order to retain acceptable vehicle performance.
Single-stage boosting has been sufficient for previous
requirements, but as customers and governments mandate lower fuel
consumption and reduced emissions, two-stage boosting will be
required for downsized and downsped engines in order to maintain
performance feel for common class B, C, and D vehicles.
A 1.6L-I4 diesel engine model was created, and three different
two-stage boosting systems were explored through engine and vehicle
level simulation to reflect the industry's current view of the
limit of downsizing without degrading combustion efficiency with
cylinder volumes below 400 cm₃. Some current engines are already at
this size, so downspeeding will become much more important for
reducing fuel consumption in the future. Twin-turbocharger,
supercharger-turbocharger, and turbocharger-supercharger boosting
systems were explored using GT-Power and GT-Drive simulation to
demonstrate each boosting system's impact on BSFC and drive
cycle fuel economy over the NEDC and ARTEMIS (urban) cycle.
Transmission shift points were altered to downspeed each
configuration to match equivalent vehicle performance while
maintaining the same transmission and final drive ratios to not
impact vehicle creep speed and gradeability. The twin sequential
turbocharged engine had slightly lower full load BSFC values than
the supercharged engines, but this slight penalty was easily
overcome through vehicle downspeeding by matching performance of
the twin turbo vehicle. Vehicle fuel consumption for the
supercharger-based boosting systems was 8-10% lower over the NEDC
and 12-14% lower over the ARTEMIS (urban) cycle when compared to a
twin sequential turbocharger boosting system.
Citation: Wetzel, P., "Downspeeding a Light Duty Diesel Passenger Car with a Combined Supercharger and Turbocharger Boosting System to Improve Vehicle Drive Cycle Fuel Economy," SAE Technical Paper 2013-01-0932, 2013, https://doi.org/10.4271/2013-01-0932. Download Citation