(1) Working cycle - a closed cycle consisting of four working processes: intake, compression, work and exhaust. Only by carrying out these processes repeatedly can the internal combustion engine work continuously.

（2）上、下止点——活塞顶离曲轴回转更远处，即活塞位置，称为上止点；活塞顶离曲轴回转更近处，即活塞点，称为下止点。在上、下止点处，活塞的运动速度为零。

(2) Top and bottom dead center - the farthest distance between the piston crown and the rotation center of the crankshaft, that is, the highest position of the piston, which is called the top dead center; The place where the piston crown is closest to the rotation center of the crankshaft, that is, the lowest point of the piston, is called the bottom dead center. At the top and bottom dead center, the movement speed of the piston is zero.

（3）曲柄半径——曲轴的回转半径R。

(3) Crank radius - the turning radius r of the crankshaft.

（4）活塞行程——上、下止点间的距离S。S=2R。

(4) Piston stroke - distance s between top and bottom dead center. S=2R。

（5）气缸工作容积——活塞从上止点到下止点所扫过的容积Vh

(5) Working volume of cylinder - the volume VH swept by the piston from TDC to BDC

（6）燃烧室容积——活塞位于上止点时活塞顶面以上与气缸盖底面以下之间形成的容积Vc。

(6) Combustion chamber volume - the volume VC formed between the top surface of the piston and the bottom surface of the cylinder head when the piston is at the top dead center.

（7）气缸总容积——气缸工作容积和燃烧室容积之和Va。Va＝Vc＋Vh。

(7) Total cylinder volume - sum of cylinder working volume and combustion chamber volume, Va. Va＝Vc＋Vh。

（8）压缩比——气体压缩前的容积与气体压缩后的容积之比值，即气缸总容积与燃烧室容积之比ε。压缩比是发动机中一个非常重要的概念，它表示了气体的压缩程度。

(8) Compression ratio - the ratio of the volume before gas compression to the volume after gas compression, that is, the ratio of the total volume of the cylinder to the volume of the combustion chamber ε。 Compression ratio is a very important concept in engine, which indicates the compression degree of gas.

（9）发动机排量——多缸发动机各气缸工作容积的总和VL。VL=Vh×I；其中，Vh—气缸工作容积；I—气缸数目。

(9) Engine displacement - the sum of the working volumes of each cylinder of a multi cylinder engine, VL. VL=Vh × I； Where, VH - working volume of cylinder; I - number of cylinders.

我们又进入了紧张有序的工作状态，这时候，如果天然气发电机组突然不转动了，这会给工作带来很大的麻烦，特别是生产制造单位，耽误工作就要延误发货日期。这对厂家来说是一种损失。因此，发电机组突然不转动了，就要拿出合理有效的解决方案。一般来说：发电机组突然出现不转动的现象是因为以下两个方面：

We have entered a tense and orderly working state again. At this time, if the natural gas generator unit suddenly stops rotating, it will bring great trouble to the work, especially the production and manufacturing units. If we delay the work, we will delay the delivery date. This is a loss for the manufacturer. Therefore, if the generator set suddenly does not rotate, it is necessary to come up with a reasonable and effective solution. Generally speaking, the sudden non rotation of the generator set is due to the following two aspects:

1.是较长时间停放后次启动，发电机不能转动。

1. It is the first start after parking for a long time, and the generator cannot rotate.

2.发电机组在运行中出现异常响声突然熄火，再启动时发电机不能转动。

2. The generator set suddenly stalls due to abnormal noise during operation, and the generator cannot rotate during restart.

如果出现上述两个方面的问题，我们应当考虑是什么原因导致造成的。

If there are problems in the above two aspects, we should consider what causes them.

1. 发电机组在运行过程中突然出现异响并导致熄火，原因多为：抱瓦、黏缸、曲轴或连杆折断导致发电机不能启动。如果进气门和出气门卡死，以至于不能进气、出气，或者是活塞项部有异物，也会造成启动时发电机不转动而无法启动。

1. Abnormal noise occurs suddenly during the operation of the generator set and leads to flameout. Most of the reasons are: bearing, sticking cylinder, broken crankshaft or connecting rod, resulting in the failure of the generator to start. If the inlet valve and outlet valve are stuck so that the inlet and outlet cannot be started, or there is foreign matter in the piston neck, the generator will not rotate and cannot be started during startup.

2.发电机组如果停滞长时间不用，次使用也会出现故障：比如蓄电池极柱接触不良，启动线路未接通或蓄电池线路内部断路，线路不通；蓄电池存电量不足，不能带动启动机旋转等。或启动线路本身有断路之处；启动机磁力开关有故障；启动机齿轮未能与发电机飞轮齿圈啮合而导致启动不了。

2. If the generator set is not used for a long time, it will also fail in the first use: for example, the battery pole is in poor contact, the starting line is not connected, or the internal circuit of the battery line is open, and the line is not connected; The storage capacity of the battery is insufficient to drive the starter to rotate, etc. Or there is an open circuit in the starting line itself; The magnetic switch of the starter is faulty; The starter gear fails to mesh with the flywheel ring gear of the generator, resulting in failure to start.

如果天然气发电机组突然不转动了，我们可以下两种方式调整：

If the natural gas generator set suddenly stops rotating, we can adjust it in the following two ways:

一是可分别对极柱，蓄电池线路、启动机磁力开关、启动线路进行检修。

First, the pole post, battery circuit, starter magnetic switch and starting circuit can be overhauled respectively.