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.%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1 300 r/min,200 N·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.
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