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.

發電機組為何易出現敲擊聲

Why is the generator set prone to knocking sound

1、燃氣發電機組供油時間過早。柴油過早噴人燃燒室后提早使氣缸燃燒做功，使發動機工作粗暴，發出清脆有節奏的金屬敲擊聲，且常引起反轉。

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、噴油器針閥磨損，或噴油器噴油壓力太高，使供油量增多；噴油泵出油閻減壓環帶磨損，導致柴油發電機組減壓環帶的減壓作用失效，高壓油管內剩余壓力增高，造成噴油器噴油后滴泊，使氣缸內在燃燒前便積累大量柴油，一旦燃燒時爆炸力猛增，引起“敲缸”，同時排氣管放炮冒黑煙。

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、發電機組長時間超負荷作業，供油量過大，或選用柴油不符合要求，著火性差也會導致“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、活塞與氣缸早期磨損后間隙變大，在氣缸上部發出有節奏的“嗒嗒”聲響，怠速時響聲明顯，中、高速時響聲減弱。活塞銷與連桿小頭的銅套或活塞銷與銷座孔配合松曠，工作中互相撞擊，在氣缸上發出清脆而連貫的響聲．轉速越高，響聲越大。

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、氣門彈簧折斷或彈力減弱而使氣門下落過多(末落入缸內)，氣門間隙過小或配氣相位有誤而使氣門開度變大，修理時換裝的氣門座圈太厚而使氣門頭高出缸蓋下平面過多。以上因素均使柴油發電機組活塞上行時氣門頭拍擊活塞頂，發出敲擊聲(在缸蓋罩附近可聽到金屬清脆的“嗒嗒”聲)，響聲隨發動機轉速變化而時強時弱，排氣冒黑煙，有時有放炮現象。

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、曲軸主軸承、連桿軸承間隙過大，工作中軸瓦與軸頸發生撞擊，在缸體下部發出沉網而堅實的“嘡嘡”撞擊聲，并隨轉速和負荷增大而增大，嚴重時機體發生震動。多缸發動機組的個別缸供油時間過早，供油量過多，噴泊器滴油，壓縮力不足時，發動機組也會發出不均勻的敲擊聲。

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.