Abnormal Noise Analysis in the Piston Ring of Diesel Generator Set

by Starlight Generator dieselgeneratortech

The staff of diesel generator set manufacturers are gradually sorting out the fault performance of different brand and model equipment such as Cummins diesel generator set, Volvo diesel generator set, and silent diesel generator set. In this process, some abnormal sounds caused by diesel generator set faults are the focus of research. Next, let's briefly talk about one of the abnormal noises.

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Abnormal noise at the piston ring of diesel generator set: The abnormal noise at the piston ring mainly includes the metal tapping sound of the piston ring, the leakage sound of the piston ring, and the abnormal noise caused by excessive carbon accumulation.

(1) The metal tapping sound of the piston ring. After long-term operation of the diesel generator set engine, the cylinder wall is worn out, but the upper part of the cylinder wall that is not in contact with the piston ring almost maintains its original geometric shape and size, which creates a step on the cylinder wall. If an old cylinder gasket is used or a new one is replaced with a thinner gasket, the working piston ring will collide with the cylinder wall steps, making a dull "popping" metal impact sound. If the engine speed increases, the abnormal noise will also increase accordingly. In addition, if the piston ring is broken or the gap between the piston ring and the ring groove is too large, it can also cause a loud knocking sound.

(2) The sound of air leakage from the piston ring. The weakened elasticity of the piston ring, excessive gap or overlapping openings, and grooves on the cylinder wall can all cause air leakage in the piston ring. The sound is a "drinking" or "hissing" sound, and when there is a severe air leak, a "popping" sound is emitted. The diagnostic method is to turn off the engine when the water temperature reaches 80 ℃ or above. At this time, a small amount of fresh and clean engine oil can be injected into the cylinder, and the crankshaft can be turned several times before restarting the engine. If the abnormal noise disappears but reappears soon after, it can be concluded that the piston ring is leaking.

(3) Abnormal noise caused by excessive carbon accumulation. When there is too much carbon buildup, the abnormal noise emitted from the cylinder is a sharp sound. Due to the carbon buildup being burned red, the engine has the symptom of premature ignition and is difficult to shut down. The formation of carbon deposits on the piston ring is mainly due to inadequate sealing between the piston ring and the cylinder wall, excessive gap between the openings, reverse installation of the piston ring, and overlapping of the ring ports. This causes lubricating oil to flow up and high-temperature and high-pressure gas to flow down, causing combustion at the piston ring, resulting in the formation of carbon deposits and even sticking to the piston ring, causing the piston ring to lose its elasticity and sealing effect. After replacing the piston ring with a suitable specification, this fault can be eliminated.

In addition to the abnormal sound at the piston ring of the diesel generator set, the piston crown and cylinder head, cylinder knocking sound, piston pin knocking sound, and abnormal valve sound are all precursors to faults. Generally speaking, abnormal noises can appear relatively obvious and easily attract everyone's attention. Once an abnormality is detected, everyone needs to quickly identify the root cause of the fault according to the law, carry out timely maintenance work, and restore the equipment to its good working state.

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