In the working project of gas generator set, it is easy to send out crisp metal knocking sound or low dull knocking sound in the upper and middle of the cylinder block, which is called "cylinder knocking" fault. What is the reason for the knocking sound of generator set? Now let's analyze the reasons.

发电机组为何易出现敲击声

Why is the generator set prone to knocking sound

1、燃气发电机组供油时间过早。柴油过早喷人燃烧室后提早使气缸燃烧做功，使发动机工作粗暴，发出清脆有节奏的金属敲击声，且常引起反转。

1. The fuel supply time of gas generator set is too early. After the diesel oil is injected into the combustion chamber prematurely, the cylinder burns and works early, which makes the engine work rough, sends out a crisp and rhythmic metal knocking sound, and often causes reversal.

2、喷油器针阀磨损，或喷油器喷油压力太高，使供油量增多；喷油泵出油阎减压环带磨损，导致柴油发电机组减压环带的减压作用失效，高压油管内剩余压力增高，造成喷油器喷油后滴泊，使气缸内在燃烧前便积累大量柴油，一旦燃烧时爆炸力猛增，引起“敲缸”，同时排气管放炮冒黑烟。

2. The needle valve of the fuel injector is worn, or the fuel injection pressure of the fuel injector is too high, which increases the fuel supply; The wear of the pressure reducing ring belt at the outlet of the fuel injection pump leads to the failure of the pressure reducing effect of the pressure reducing ring belt of the diesel generator set, and the residual pressure in the high-pressure oil pipe increases, resulting in the dropping of the fuel injector after fuel injection, so that a large amount of diesel will accumulate in the cylinder before combustion. Once the explosion force increases sharply during combustion, it will cause "cylinder knocking" and black smoke from the exhaust pipe.

3、发电机组长时间超负荷作业，供油量过大，或选用柴油不符合要求，着火性差也会导致“敲缸”

3. The generator is overloaded for a long time, the oil supply is too large, or the selection of diesel oil does not meet the requirements, and the poor ignition will also lead to "cylinder knocking"

4、活塞与气缸早期磨损后间隙变大，在气缸上部发出有节奏的“嗒嗒”声响，怠速时响声明显，中、高速时响声减弱。活塞销与连杆小头的铜套或活塞销与销座孔配合松旷，工作中互相撞击，在气缸上发出清脆而连贯的响声．转速越高，响声越大。

4. The clearance between the piston and the cylinder becomes larger after early wear, and a rhythmic "click" sound is sent out at the upper part of the cylinder. The sound is obvious at idle speed and weakened at medium and high speed. The copper sleeve of the piston pin and the small end of the connecting rod or the piston pin and the pin seat hole fit loosely, collide with each other during work, and make a crisp and continuous sound on the cylinder. The higher the speed, the greater the sound.

5、气门弹簧折断或弹力减弱而使气门下落过多(末落入缸内)，气门间隙过小或配气相位有误而使气门开度变大，修理时换装的气门座圈太厚而使气门头高出缸盖下平面过多。以上因素均使柴油发电机组活塞上行时气门头拍击活塞顶，发出敲击声(在缸盖罩附近可听到金属清脆的“嗒嗒”声)，响声随发动机转速变化而时强时弱，排气冒黑烟，有时有放炮现象。

5. The valve spring is broken or the elastic force is weakened, which makes the valve fall too much (the end falls into the cylinder), the valve clearance is too small or the valve timing is wrong, which makes the valve opening larger, and the valve seat ring replaced during repair is too thick, which makes the valve head too much higher than the lower plane of the cylinder head. All the above factors make the valve head slap the piston crown when the piston of the diesel generator set goes up, making a knocking sound (the crisp "click" sound of metal can be heard near the cylinder head cover). The sound is strong and weak with the change of engine speed, black smoke is emitted from the exhaust, and sometimes there is shooting.

6、曲轴主轴承、连杆轴承间隙过大，工作中轴瓦与轴颈发生撞击，在缸体下部发出沉网而坚实的“嘡嘡”撞击声，并随转速和负荷增大而增大，严重时机体发生震动。多缸发动机组的个别缸供油时间过早，供油量过多，喷泊器滴油，压缩力不足时，发动机组也会发出不均匀的敲击声。

6. The clearance between the crankshaft main bearing and connecting rod bearing is too large. During operation, the bearing bush collides with the journal, and a net sinking and solid "bang bang" impact sound is sent out at the lower part of the cylinder block, which increases with the increase of speed and load. In serious cases, the machine body vibrates. When the oil supply time of individual cylinders of multi cylinder engine group is too early, the oil supply is too much, the oil is dripping from the sprayer, and the compression force is insufficient, the engine group will also make an uneven knocking sound.