一台东方红-75型拖拉机作业时,发动机冒黑烟十分明显,经检查是喷油嘴针阀粘焦造成的,但连续更换两个新喷油嘴都很快又被粘焦。分析原因是喷油嘴挺杆上针阀尾座孔磨损过深,使针阀一直处于半开启位置上,断油不彻底而产生粘焦,显然,胃黑烟的原因与此有关。装配喷油器时,判断针阀能关闭的依据是:在束装油嘴压帽时,油嘴的环形面与喷油器体接触面 When a DFH-75 tractor operated, the engine was smoky. After checking, it was caused by sticky cohesion of the nozzle needle. However, the two consecutive new injector nozzles were quickly cohered. Analysis of the reason is that the tappet on the tappet needle tail hole wear too deep, so that the needle has been in a semi-open position, not completely off the oil and resulting sticky coke, apparently, the reason for stomach dark smoke related. When assembling the injector, it is judged that the needle valve can be closed on the basis that when the nozzle is squeezed, the annular surface of the nozzle and the injector body contact surface