As the power system of construction machinery, diesel engines provide the power required to operate machinery. Obstacles affect normal production. Therefore, observing the color of exhaust gas is very important for diagnosing diesel engine faults. The normal color of diesel fuel after complete combustion is usually light gray or dark gray. Diesel in operation may cause abnormal conditions such as black smoke, white smoke and blue smoke. This is the condition for determining the failure of the diesel engine. Diesel is a complex hydrocarbon. The unburned diesel fuel injected into the combustion chamber is decomposed at a high temperature. When discharged, it is discharged together with the exhaust gas and becomes black smoke. Black smoke is a sign of incomplete combustion of fuel in the combustion chamber. The wear of the piston ring and cylinder liner will result in insufficient compression pressure, which will change the normal mixture ratio at the end of the cylinder compression stroke, thereby burning fuel and carbon under oxygen-free conditions. The fuel injector does not atomize or drip, so the fuel cannot be completely mixed with the air in the cylinder.

(1) Because the advance angle of the fuel is too large, the fuel is quickly injected into the combustion chamber. The low pressure and high temperature in the cylinder cannot ignite the fuel. When the piston moves upward, the cylinder reaches a certain pressure and temperature, and the combustible mixture burns.

(2) The fuel supply advance angle is too small, and the cylinder fuel is too slow. Before forming a combustible mixture, some fuel must be separated or discharged. The fuel discharged with the exhaust gas decomposes at high temperature to form black smoke. As more oil enters the cylinder, more gas cannot be completely burned, thereby reducing fuel oil. In addition, heavy workload, poor fuel quality and low working temperature will exhaust all exhaust gas. The lubricating oil enters the cylinder, is heated and evaporates into blue oil and gas.

This is the introduction to the black smoke of the micro-excavator engine, I hope it will be helpful to you.