Biogas generator set, like other generator sets, diesel generator set and gasoline generator set, is used as power supply equipment, but the fuel used is different. In the process of using the biogas generator set, the unit will inevitably fail. When the cylinder head of the unit makes a snap sound, the sound is obviously transmitted from the exhaust pipe. What's going on?

其原因有：

The reasons are:

1、因凸轮轴进、排气凸轮磨损，使气门开度变小；

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

2、沼气发电机组的气门挺杆与凸轮轴接触部位磨出凹坑，导致进、排气门开启时间过短，气流通过气门时因过于急促而发出啪、啪声。如此类故障发生在排气部位，响声被排气声所掩盖，所以不易听清；故障发生在进气凸轮部位，响声就非常明显了。

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，气门间隙太大，也会导致进、排气急促而发生啪、啪的响声，诊断故障时应区别。气缸盖罩壳处发出的、的响声，且响声次数有规律地随沼气发电机组转速的增高而增多，随转速的降低而减少，基本上是曲轴转两转发出一、二次响声。产生这种响声的原因是：

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.气门间隙过大，应重新按标准调整；

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

2.沼气发电机组气门杆与气门导管配合间隙或气门摇臂衬套与摇臂轴间隙过大所致。此时，应更换新件。

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.气缸上部发出有节奏的尖锐的铛、铛声，刚启动时响声较大，随着机温的升高，敲击声逐渐减小，并可能消失。这种声音是因为气缸套与活塞配合间隙过大而发出的。当气缸套与活塞裙部配合间隙超过0.42mm时，应更换新件。

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.沼气发电机组气缸上部发出有节奏的尖锐的铛、铛声，但不随机温的升高而减轻，在加大油门时，响声增大；减小油门时，响声减小；忽然关掉油门时响声消失。这种敲击声俗称：敲缸，表明沼气发电机组供油时间过早。

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.

沼气发电机组气缸上部发出清脆的金属敲击声，在低转速或突然改变转速时容易听到。其原因是：活塞销与活塞销座孔或连杆铜套的间隙过大而发出敲击声。为了区别究竟是由于供油时间早还是由于活塞和缸套间隙过大而产生的敲击声，有必要拆下机体后盖板，不按减压阀，将活塞盘转至压缩上止点，然后左右扳动飞轮。

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.