1. The valve opening becomes smaller due to the wear of camshaft inlet and exhaust cams;

2、沼氣發(fā)電機(jī)組的氣門挺桿與凸輪軸接觸部位磨出凹坑，導(dǎo)致進(jìn)、排氣門開(kāi)啟時(shí)間過(guò)短，氣流通過(guò)氣門時(shí)因過(guò)于急促而發(fā)出啪、啪聲。如此類故障發(fā)生在排氣部位，響聲被排氣聲所掩蓋，所以不易聽(tīng)清；故障發(fā)生在進(jìn)氣凸輪部位，響聲就非常明顯了。

2. Pits are worn at the contact part between the valve tappet and camshaft of biogas generator set, resulting in too short opening time of inlet and exhaust valves and too fast air flow through the valves. Such faults occur at the exhaust part, and the sound is covered by the exhaust sound, so it is not easy to hear; The fault occurs at the intake cam, and the noise is very obvious.

另外，氣門間隙太大，也會(huì)導(dǎo)致進(jìn)、排氣急促而發(fā)生啪、啪的響聲，診斷故障時(shí)應(yīng)區(qū)別。氣缸蓋罩殼處發(fā)出的、的響聲，且響聲次數(shù)有規(guī)律地隨沼氣發(fā)電機(jī)組轉(zhuǎn)速的增高而增多，隨轉(zhuǎn)速的降低而減少，基本上是曲軸轉(zhuǎn)兩轉(zhuǎn)發(fā)出一、二次響聲。產(chǎn)生這種響聲的原因是：

In addition, if the valve clearance is too large, it will also lead to rapid intake and exhaust, resulting in crackle and crackle. It should be distinguished when diagnosing faults. The sound from the cylinder head cover increases regularly with the increase of the speed of the biogas generator set and decreases with the decrease of the speed. Basically, the crankshaft rotates twice to make primary and secondary sound. The reason for this noise is:

1.氣門間隙過(guò)大，應(yīng)重新按標(biāo)準(zhǔn)調(diào)整；

1. If the valve clearance is too large, it shall be adjusted again according to the standard;

2.沼氣發(fā)電機(jī)組氣門桿與氣門導(dǎo)管配合間隙或氣門搖臂襯套與搖臂軸間隙過(guò)大所致。此時(shí)，應(yīng)更換新件。

2. The matching clearance between valve stem and valve guide of biogas generator set or the clearance between valve rocker arm bushing and rocker arm shaft is too large. At this time, replace it with a new one.

3.氣缸上部發(fā)出有節(jié)奏的尖銳的鐺、鐺聲，剛啟動(dòng)時(shí)響聲較大，隨著機(jī)溫的升高，敲擊聲逐漸減小，并可能消失。這種聲音是因?yàn)闅飧滋着c活塞配合間隙過(guò)大而發(fā)出的。當(dāng)氣缸套與活塞裙部配合間隙超過(guò)0.42mm時(shí)，應(yīng)更換新件。

3. The upper part of the cylinder emits rhythmic and sharp clang, which is loud at the beginning of startup. With the increase of machine temperature, the knocking sound gradually decreases and may disappear. This sound is caused by excessive clearance between cylinder liner and piston. When the fit clearance between cylinder liner and piston skirt exceeds 0.42mm, replace it with a new one.

4.沼氣發(fā)電機(jī)組氣缸上部發(fā)出有節(jié)奏的尖銳的鐺、鐺聲，但不隨機(jī)溫的升高而減輕，在加大油門時(shí)，響聲增大；減小油門時(shí)，響聲減小；忽然關(guān)掉油門時(shí)響聲消失。這種敲擊聲俗稱：敲缸，表明沼氣發(fā)電機(jī)組供油時(shí)間過(guò)早。

4. The rhythmic and sharp clang and clang sound is emitted from the upper part of the cylinder of the biogas generator set, but it does not decrease with the increase of temperature. When the accelerator is increased, the sound increases; When the throttle is reduced, the sound is reduced; The sound disappeared when the accelerator was suddenly turned off. This knocking sound is commonly known as cylinder knocking, which indicates that the oil supply time of biogas generator set is too early.

沼氣發(fā)電機(jī)組氣缸上部發(fā)出清脆的金屬敲擊聲，在低轉(zhuǎn)速或突然改變轉(zhuǎn)速時(shí)容易聽(tīng)到。其原因是：活塞銷與活塞銷座孔或連桿銅套的間隙過(guò)大而發(fā)出敲擊聲。為了區(qū)別究竟是由于供油時(shí)間早還是由于活塞和缸套間隙過(guò)大而產(chǎn)生的敲擊聲，有必要拆下機(jī)體后蓋板，不按減壓閥，將活塞盤轉(zhuǎn)至壓縮上止點(diǎn)，然后左右扳動(dòng)飛輪。

The upper part of the cylinder of the biogas generator set emits a crisp metal knocking sound, which is easy to hear at low speed or sudden change of speed. The reason is that the clearance between the piston pin and the piston pin seat hole or the copper sleeve of the connecting rod is too large to make a knocking sound. In order to distinguish whether the knocking sound is caused by early oil supply time or excessive clearance between piston and cylinder liner, it is necessary to remove the rear cover plate of the engine body, turn the piston disc to the compression top dead center without pressing the pressure reducing valve, and then pull the flywheel left and right.