Development of BYD Flat Engine for Luxury Hybrid Vehicles

<div>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.</div>