柴油发电机组故障的原因通常是多方面因素造成的,不同故障表现出不同的现象,要排除故障,必须先查明故障的原因,在实践中通过看、听、摸、嗅等感觉,来发现柴油机异常的表现,从而发现问题、解决问题,消除故障。
判断柴油机故障的一般原则是:结合结构、联系原理、弄清现象、结合实际,从简到繁、由表及里、按系分段、查找原因。在长期的生产实践中,人们摸索总结出“一看、二听、三摸、四嗅”的一套检查方法,通过仪表监测和人体器官的感受,去观察和判断柴油机的运行情况。
运转异常
柴油机长期运转后,发生了故障,通常会遇到下列几种现象。
(1)运转时声音异常柴油机运转时发出不正常的敲击声、放炮声、吹嘘声、排气声、周期性的磨擦声等。
(2)运转异常柴油机不易启动、工作时出现剧烈震动,拖不动负载,转速不稳定等。
(3)外观异常柴油机排气管冒白烟、黑烟、蓝烟,各系统出现漏油、漏水、漏气等。
(4)温度异常机油温度或冷却水温度过高,轴承过热等。
(5)气味异常柴油机运行时,发出臭味、焦味、烟味等气味。
柴油发电机组运行进,发现上述异常现象后,必须进行仔细的调查,根据故障现象,分析判断找出故障的部位和原因。有时一种故障可能有好几种异常现象,例如高压油泵磨损后,既可表现启动困难,也可表现输出功率不足,还可表现低速运转不稳定等现象。有时一种异常现象,可能有几种故障造成的。因此,柴油机运行时出现异常现象,必须认真查清产生异常现象的原因,这就要求我们善于作分析推理判断,透过现象抓实质,找出发生故障的原因和部位,将故障排除。
检查方法
(1)根据异常的声响来判别故障的部位用一把通心改锥或用一根半米长一端磨尖的细铁条,进行“听针判断”,一端贴耳,另一端触及各检查部位表面,可较清晰地监听到异常声响产生的部位,声响的大小和性质。不同部位发出声响往往是不同的。例如主轴承间隙过大发生冲击声是沉闷的,气门与活塞碰击声是清脆的,若飞轮键槽配合松动发出“唝!唝!”的撞击声等等,因此,根据不同声响,来判断故障的部位。
(2)用局部停止法来判断经故障分析后,若怀疑故障是由某一汽缸引起的,可停止该缸工作,观察故障现象是否消失,从而确定故障原因和部位。例如柴油机冒黑烟,分析为某缸喷油嘴喷孔堵塞,可对该缸停止供油,若黑烟消失,说明判断正确。
(3)用比较法来判断根据故障分析,怀疑故障可能是由于某一零、部件所造成的,可将该零件(或部件)更换一只新件,然后开机运行比较柴油机前后工作情况是否有变化,从而找出故障原因。
(4)用试探法来判断根据分析故障原因一时难以判断,可用改变局部范围内的技术状态,观察柴油机工作性能是否有影响,以此来判别故障的原因。例如柴油机发不出规定的功率,怀疑某缸压缩冲程压力不足,是汽缸与活塞间隙较大密封不严造成的,此时将缸盖打开向汽缸注入少量机油,以改善密封状况,然后重新装好缸盖,开机试验若压力增大,输出功率增加,说明分析是正确的。
柴油发电机组经长时间使用后,其故障现象很多,由于柴油机各种型号不同,国产的和进口的其结构和使用环境不同,故障原因也有所不同,因此,在处理问题时,对具体问题应根据不同情况作具体分伯。正确分析和判断柴油机故障的原因,是一项细致的工作,不应在未弄清故障原因之前就乱拆一通,这样不但不能消除故障,而且可能在重装拆开的零、部件时,达到不技术要求造成新的故障。
The causes of faults in diesel generator sets are usually caused by various factors, and different faults exhibit different phenomena. To eliminate faults, it is necessary to first identify the cause of the fault. In practice, by looking, listening, touching, smelling, and other senses, the abnormal performance of the diesel engine can be discovered, and problems can be found, solved, and eliminated.
The general principle for judging diesel engine faults is to combine structure, connection principles, clarify phenomena, and combine reality, from simple to complex, from the surface to the inside, segment by system, and find the cause. In long-term production practice, people have explored and summarized a set of inspection methods of "one look, two listen, three touch, and four smell", which observe and judge the operation of diesel engines through instrument monitoring and the feeling of human organs.
Abnormal operation
After long-term operation, diesel engines often encounter the following phenomena when they malfunction.
(1) Abnormal sound during operation: The diesel engine produces abnormal knocking, blasting, blowing, exhaust, periodic friction, etc.
(2) Abnormal operation: The diesel engine is difficult to start, experiences severe vibrations during operation, cannot drag the load, and has unstable speed.
(3) Abnormal appearance: The diesel engine exhaust pipe emits white smoke, black smoke, and blue smoke, and various systems are leaking oil, water, and gas.
(4) Abnormal temperature, high oil temperature or cooling water temperature, bearing overheating, etc.
(5) Abnormal odor: When the diesel engine is running, it emits odors such as foul smell, burnt smell, and smoke smell.
After the operation of the diesel generator set and the discovery of the above-mentioned abnormal phenomena, a careful investigation must be conducted to analyze and determine the location and cause of the fault based on the fault symptoms. Sometimes a fault may have several abnormal phenomena, such as difficulty in starting, insufficient output power, and unstable low-speed operation after the wear of the high-pressure oil pump. Sometimes an abnormal phenomenon may be caused by several faults. Therefore, when abnormal phenomena occur during the operation of diesel engines, it is necessary to carefully investigate the causes of the abnormal phenomena. This requires us to be good at analyzing, reasoning and judging, grasping the essence through the phenomena, identifying the causes and parts of the faults, and eliminating them.
Inspection method
(1) To determine the location of the fault based on abnormal sounds, use a through center screwdriver or a thin iron bar that is half a meter long and sharpened at one end for "listening needle judgment". Place one end on the ear and touch the surface of each inspection site at the other end to clearly monitor the location, size, and nature of the abnormal sound. The sound produced by different parts is often different. For example, if the clearance between the main bearing is too large, the impact sound will be dull, the collision sound between the valve and piston will be crisp, and if the flywheel keyway is loose, it will make a "唝! 唝!" impact sound, etc. Therefore, based on different sounds, the location of the fault can be determined.
(2) Using the local stop method to determine after fault analysis, if it is suspected that the fault is caused by a certain cylinder, the cylinder can be stopped to observe whether the fault phenomenon disappears, in order to determine the cause and location of the fault. For example, if a diesel engine emits black smoke, it can be analyzed as a blockage in the fuel injector hole of a certain cylinder, and the fuel supply to that cylinder can be stopped. If the black smoke disappears, it indicates that the judgment is correct.
(3) Using the comparative method to determine, based on fault analysis, if it is suspected that the fault may be caused by a certain component or part, the component (or part) can be replaced with a new one, and then the diesel engine can be started and operated to compare whether there are any changes in the working conditions before and after, in order to identify the cause of the fault.
(4) It is difficult to determine the cause of the fault based on the analysis using the probing method. By changing the technical state within a local area and observing whether the performance of the diesel engine is affected, the cause of the fault can be determined. For example, if a diesel engine cannot produce the specified power and it is suspected that the compression stroke pressure of a certain cylinder is insufficient, it is caused by a large gap between the cylinder and the piston and poor sealing. At this time, the cylinder head is opened and a small amount of oil is injected into the cylinder to improve the sealing condition. Then, the cylinder head is reinstalled. If the pressure increases and the output power increases during the start-up test, it indicates that the analysis is correct.
After long-term use, diesel generator sets have many fault phenomena. Due to the different models of diesel engines, as well as the different structures and operating environments of domestic and imported ones, the causes of faults are also different. Therefore, when dealing with problems, specific problems should be classified according to different situations. Accurately analyzing and determining the cause of diesel engine failures is a meticulous task, and should not be dismantled without understanding the cause of the failure. This not only fails to eliminate the fault, but may also result in new failures due to non-technical requirements when reinstalling disassembled parts and components.