How to determine the operation status of diesel generator sets from sound? Diesel generator sets belong to mechanical equipment and are often prone to malfunctions during long-term operations. The method of identifying faults is to listen, look, and check. The most effective and direct step is to judge through the sound of the generator, and small faults can be resolved through the sound to prevent major accidents from occurring. Below, we will teach you how to determine the working status of a diesel generator set from its sound.
1、 When the diesel generator is running at low speed (idle), a clear metal tapping sound can be heard next to the valve cover. This sound is caused by an impact between the valve and rocker arm, mainly due to excessive valve clearance. Valve clearance is one of the specific technical parameters of diesel generators. If the valve clearance is too large or too small, the diesel generator cannot operate normally. The excessive valve clearance causes excessive displacement between the rocker arm and the valve, resulting in a significant impact force during contact. As a result, a metal tapping sound of "clicking" is produced. This sound is common in diesel generators after long-term operation, so the valve clearance should be readjusted every 300 hours of operation.
2、 When a diesel generator suddenly drops from high-speed operation to low-speed, the sound of "dang, dang, dang" can be clearly heard in the upper part of the cylinder. This is one of the common problems of diesel generators, and the specific reason is that the clearance between the piston tip and the connecting rod liner is too large, resulting in a lateral dynamic imbalance caused by sudden changes in engine speed. This causes the piston tip to rotate inside the connecting rod liner while swinging left and right, causing the piston tip to collide with the connecting rod liner and produce a sound. To avoid greater damage, unnecessary waste, and economic losses, the piston tips and connecting rod bushings should be replaced in a timely manner to ensure the normal and efficient operation of the diesel generator.
3、 When the diesel generator is running, a heavy and dull knocking sound can be heard at the lower part of the diesel generator cylinder body, especially during high load operation of the diesel generator, this sound becomes more prominent. This kind of noise is caused by abnormal friction between the crankshaft bearing or the main shaft bearing and the main journal, mainly due to the large gap between the main shaft crankshaft neck and the crankshaft bearing or the main shaft bearing, causing uneven wear between the crankshaft neck and the main shaft bearing or the main shaft bearing, resulting in abnormal friction and this heavy, dull knocking sound. Upon hearing this sound, the operation of the diesel generator set should be stopped immediately, as if this sound continues to cause the diesel generator set to continue working without inspection and repair, it is likely to result in a situation of "sticking tiles" and "burning shafts". To prevent such a serious malfunction, work should be stopped immediately and the crankshaft bearing bolts should be checked for looseness. If not, the crankshaft, main shaft bearings, or crankshaft bearings should be removed immediately. Professional personnel should measure and calculate the clearance value between them, compare them with the specified parameters, and strictly inspect the damage of the main shaft and crankshaft. If necessary, repair or replacement should be carried out.
4、 When a diesel generator is running, a clear and crisp sound of the piston striking the engine body can be heard at the top of the cylinder, commonly known as "pounding the cylinder". The fundamental cause of this malfunction is that the fuel injection advance angle of the diesel generator is too small. As is well known, the fuel supply advance angle of diesel generators is one of the specific technical data of diesel generators. The accuracy of the fuel supply advance angle will directly affect whether the diesel generator can work normally, and directly affect whether the diesel generator can provide normal power, affecting the working condition of the entire machine. In order for the formation and combustion process of the mixture to proceed normally, diesel generators must have a certain fuel injection advance angle. If the fuel injection advance angle is too small, the air injected into the cylinder will form combustible gas combustion, causing combustion instability. During the upward phase of the piston, lateral displacement and collision with the cylinder wall will occur, resulting in a knocking sound on the cylinder block.
5、 A diesel generator can hear a dull knocking sound near the cylinder block when suddenly changing its load. This sound is caused by abnormal friction between the crankshaft connecting rod journal and the connecting rod bearing, specifically due to excessive clearance between the connecting rod journal and the connecting rod bearing, resulting in local jumping. The principle and maintenance inspection strategy for producing this sound are identical to those of the crankshaft and crankshaft bearing shells.
6、 At the front cover of the diesel generator, a clear "howling" sound can be heard. This sound comes from the meshing gears inside the front cover. The excessive wear of the gears in each meshing gear leads to excessive clearance between the gears, which prevents them from entering the normal meshing state and produces this sound. The solution is to open the front cover, check the meshing condition of the gears with lead or paint, and make adjustments. If the clearance between the gears is too large, a new gear must be replaced in a timely manner.
6、 A hoarse and strong knocking sound can be heard throughout the entire length of the cylinder of a diesel generator, and this sound is more pronounced when the diesel generator is running at low speeds or experiencing sudden speed changes. The specific cause of this situation is excessive damage to the piston and cylinder, causing the gap between the piston and cylinder to be too large. When the piston moves up or down, it moves laterally inside the cylinder and swings. When it comes into contact with the cylinder wall, it intensifies wear and produces a hoarse friction sound. After this situation occurs, professional technicians should be consulted to identify the cylinder liner and piston, and if necessary, replace the piston or cylinder liner with a new one.
7、 There is a sound similar to lightly tapping an anvil with a small hammer along the upper and lower parts of the diesel generator cylinder. The specific reason for this sound is that the gap between the piston ring and the ring groove is too large, causing the piston ring to collide with the piston when running up and down, resulting in a sound similar to lightly tapping an anvil with a small hammer. After this situation occurs, the operation of the diesel generator should be stopped immediately and a new piston ring should be replaced.
8、 A collision sound can be heard from the upper part of the cylinder. This sound not only reduces the valve clearance, but also increases the impact sound. The main reason for this sound is the collision between the valve and the piston, and the main reason for this phenomenon is the mismatch of the valve clearance.
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