To meet the requirements of luxury hybrid vehicles regarding engine power,
torque, size, and NVH performance, BYD independently developed a 2.0 T flat
engine. Designs such as increased intake valve lift, widened intake valve
profile, swept piston bowl, and extended exhaust backflow region optimized
in-cylinder airflow, enabling the BYD flat engine to achieve a maximum power of
180 kW and a peak torque of 380 N·m. This engine is 820 mm in length, 430 mm in
width, and 420 mm in height, saving approximately 45% in volume compared to a
competitor engine. The lubrication challenges of the flat engine were addressed
through the coordinated implementation of a dry sump system, a multifunctional
oil pump, and piston ring orientation design. A novel parameterized modal
analysis methodology (considering phase and amplitude) was used for optimizing
NVH performance. In synergy with the sandwich-type soundproof plates and
four-sided acoustic encapsulation, the noise level (1-m sound pressure level,
four-point averaged) of the BYD flat engine is 2.2~2.9 dB(A) lower than the
lower limit of AVL’s scattering band. Owing to its desirable performance in
power output, packaging compactness, and NVH characteristics, the BYD flat
engine has been integrated into the powertrain of the Yangwang U7 model.
