The characteristics of cylinder liner cavitation damage are in the form of locally gathered deep holes. In most cases, the damaged surface is clean, free of deposition of corrosion products, and appears on one side of the liner pressure surface. With the development of diesel engine to the direction of adjustment and strengthening, cavitation has become increasingly serious.
Cavitation damage of the cylinder block and cylinder liner causes cracks and even through holes, resulting in cooling water entering the cylinder and oil, which significantly reduces the life and reliability of the diesel engine. In order to prevent cavitation, the commonly used methods are: reduce the gap between the cylinder and the piston, so as to reduce the vibration of the cylinder liner; Adopt long piston skirt part; Increase the flow rate of cooling water, improve the flow direction and the structure of cooling system; Increase the support stiffness of cylinder liner; The material and process of cylinder liner should be improved to improve its cavitation resistance and so on.
The main source of cavitation is cylinder liner vibration. When the piston reaches the top dead center, the direction of the side pressure changes, and the piston swings from one side of the cylinder liner to the opposite side, and the phenomenon of piston swing appears. Because there is a thermal gap between the piston and the cylinder liner, the swing of the piston is impact. This impact causes strong vibration of the cylinder liner.
When the liner wall vibrates, alternating stretching and compression occur in the water chamber, resulting in local high pressure and vacuum bubbles in the water near the outer wall. Under the action of high vacuum, the cooling water evaporates into bubbles, and some vacuum bubbles and bubbles occur in the tiny pinholes on the outer wall of the cylinder liner, or are squeezed into the pinholes under the action of vibration. When the vacuum bubble or bubble is ruptured by high pressure impact, the pressure shock wave is generated near the rupture zone, and the pressure can reach tens of atmospheres and impact the outer wall of the cylinder, so frequent repeated impact, the cylinder liner surface is rapidly damaged.
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Post time: Mar-24-2025