汽油发动机怠速不稳故障原因及排除

汽车发动机由于怠速不稳,造成发动机多次熄火,因而在使用中发动机起动频繁造成能源浪费、机件损耗,且对行车安全也带来一定威胁。其原因有三个方面:发动机运转件受到突发性的阻力;发动机点火系中各缸点火间隔角度发生变化;进气系统中管道密封不严产生泄漏。

Flow and Leakage Characteristics in Sealing Chamber of a Variable Geometry Hypersonic Inlet

When the variable geometry hypersonic inlet is sealed with ceramic wafers,the cavity flows inside the sealing chamber can be affected by the boundary layer near the side wall.To study the influence of the boundary layer thickness near the side wall on the flow and leakage characteristics in sealing chamber,the numerical calculation of the cavity flow in the sealing chamber under different inflow boundary layer thicknesses is carried out.The results show that three-dimensional cavity flow structures are close to being asymmetric,and the entrance pressure of the leakage path can also be affected by asymmetry;with the increase of the thickness of the boundary layer,the pressure at the cavity floor and the seal entrance decreases.Finally,the existing leakage prediction model is modified according to the distribution rule of the cavity floor and the flow properties in the leakage path.

柴油机故障快速诊断检查七则

1.供油时间过早过晚的快速诊断 (1)敲缸 发动机起动后,正常情况下可以听到轻微的金属敲击声。供油过早,可以听到象硬木锤敲击活塞似的金属敲击声,转速越低越明显,供油越早声音越清脆;供油过晚,敲击声反而不明显。当喷油嘴喷油雾化不良,使燃油自燃延迟期增加,也能引起爆炸,但比供油时间不准引起敲缸的影响要小得多,仔细观察是不难区分的。