缸内直喷汽油机两阶段喷射喷油规律研究

基于定容积法搭建了均质混合气压燃（HCCI）燃烧模式下的缸内直喷汽油机（GDI）喷油器喷油规律测试台，在保证其测试精度的基础上，研究了GDI喷油器两阶段喷油的喷射压力、喷射背压、两次喷油间隔和体积分数对其喷油规律的影响．结果表明，喷油率随喷射压力增大呈增大趋势；喷射背压只对喷油中期的喷油率有影响且随着喷射背压的增大喷油率有所下降，但喷射背压对喷油总量影响不大．试验测得的喷射间隔小于设定值．另外，两次喷射间隔较小时出现两次喷油过程重叠，使其第2次喷油率高于喷射间隔较大时的第2次喷油率．单次喷油率和喷油持续时间随着喷射体积分数增大而增大．

An experimental study of two-stage injection rate for the gasoline direct injector

Based on the constant volume method, the injection-rate test system under Homogeneous Charge Compression Ignition （HCCI） for the gasoline direct injector （GDI） is established. The influences of two-stage injection pressure, injection back pressure, injection interval and injection volume fraction on the injection rate are studied with accuracy. Results show that the injection rate increases with increasing injection pressure. Only the injection rate on middle-period injection is affected by the injection back pressure. With increasing injection back pressure, the injection rate drops. But the injection back pressure has little effect on the total fuel mass flow. The measured injection interval is shorter than the set value. In addition, the short interval causes overlap of the two-stage injection processes. The second fuel injection rate is higher than that with larger interval injection. A single injection rate and injection duration increases with increasing injection volume fraction.