基于LIVC和双VVT技术的增压直喷汽油机抑制爆震试验研究

在1台涡轮增压缸内直喷汽油机上,利用双可变气门正时(双VVT)技术结合进气门晚关凸轮轴(LIVC凸轮轴)来抑制爆震。在实现爆震抑制策略后,采用更高的几何压缩比来进一步提高热效率,改善发动机的燃油经济性。试验结果表明,在1 300r/min,200N.m这一典型的爆震工况点,通过减小气门重叠角,降低发动机扫气量,可以有效提高燃油经济性。推迟进气门和排气门相位均可以实现对爆震的抑制,结合使用LIVC凸轮,使得发动机抗爆震性能进一步大幅度提升。在原机9.3的压缩比下,点火角得以提前,接近最大扭矩点火角(MBT点)。将几何压缩比由9.3提高到了10.9后,抗爆震性能和原机相当,并明显改善了发动机的热效率,从而进一步改善了燃油经济性。

Experimental Research on Knock Suppression of Turbocharged DI Gasoline Engine Based on LIVC and Dual-VVT Technology

On a turbocharged in-cylinder DI gasoline engine,the dual VVT technology and late intake valve closing(LIVC) camshaft were used to suppress the knock.After the knock suppression,a higher geometric compression ratio was adopted to improve the heat efficiency and fuel economy.The result shows that the fuel economy can be greatly improved under the conditions of 1 300 r/min and 200 N·m by decreasing the valve overlap and reducing the engine sweeping.Based on the original 9.3 compression ratio,the ignition angle is advanced,which is close to the ignition angle of maximum torque.Increasing the geometric compression ratio from 9.3 to 10.9,the knock intensity is equivalent to the original,but the heat efficiency and hence fuel economy are improved significantly.