The so-called pit corrosion of wet cylinder liner refers to the honeycomb holes on both sides of the outer surface of the cylinder liner along the swing direction of the connecting rod after the internal combustion engine of the diesel generator set is used for a period of time. Sometimes, the inner wall of the cylinder of the internal combustion engine has not yet reached the wear limit, that is, it is broken down by pit corrosion.
1. The cause of cavitation.
(1) There are micropores, cracks and grooves in the cylinder liner material.
(2) When the machine is running, the cylinder liner vibrates.
When the diesel generator set is running, the vibration of the cylinder liner produces local high pressure and high vacuum. The cooling water evaporates into air bubbles under the action of high vacuum. Some vacuum pools and air bubbles are squeezed by vibration or occur directly in small pinholes in the outer wall of the cylinder liner. Pressure shock waves are generated near the rupture zone with pressures up to tens of atmospheres. This often occurs repeatedly, leading to rapid fatigue damage and pit corrosion on the metal surface.
If the cylinder liner of the diesel generator set is provided with acupoint erosion, it will cause great harm, water enters the cylinder. Mechanical equipment cannot be shaken. At present, there is still no effective solution for the pitting corrosion of the cylinder liner, and only some methods or measures can be taken to prevent or reduce the pitting corrosion damage of the cylinder liner.
2. Measures to prevent or reduce cavitation.
(1) The vibration of the small cylinder liner should minimize the mutual matching gap between the piston, the cylinder liner and the cylinder block, reduce the weight of the piston, and select Sichuan thick-walled cylinder liner to improve the balance effect of the crankshaft and reduce the vibration of the cylinder liner.
(2) Improve the corrosion resistance of the cylinder liner, use denser materials and coat the outer wall of the cylinder with a protective layer, chrome plating, nitriding and other methods to improve the pitting corrosion resistance of the cylinder liner.
(3) Add preservatives to cooling water.
(4) Keep the proper cooling water temperature low, and the acupoint corrosion tendency is serious. The water temperature should be around 90°C, because when the water temperature is high, air bubbles will be generated in the water, which can buffer the air cushion and reduce acupoint corrosion.
Although there are so many measures to prevent pit corrosion, pit corrosion of the cylinder liner of diesel generator sets is often unavoidable. When disassembling the cylinder liner, attention should be paid to check pit corrosion. If it is not serious, the installation direction of the cylinder liner can be adjusted by 90 degrees ( That is, the corrosion surface of the pit is perpendicular to the swing surface of the connecting rod) and continue to be used, otherwise the cylinder liner should be replaced.
The more common abnormal states of cylinder knocking of diesel generator set cylinders are as follows:
Diesel generator set knocking means that the inner wall of the cylinder liner has grooves of different depths along the direction of piston movement.
1. The reason why the diesel generator set knocks the cylinder.
(1) The running-in process of the internal combustion engine is not strictly carried out according to the running-in process.
(2) The mutual matching gap between the piston and the cylinder liner is too small.
(3) The sealing gap of the piston ring is too small, which will scratch the cylinder wall.
(4) The mechanical equipment is started at low temperature, so that the lubricating oil film cannot be formed, resulting in dry friction or semi-dry friction.
(5) The mechanical equipment is overheated during the working process and damages the oil film on the cylinder wall.
(6) Air, fuel, and oil are not well filtered, and solid particles are carried into the cylinder.
After the internal combustion engine knocks the cylinder, its harm will inevitably affect the sealing of the cylinder of the diesel generator set.
2. Measures to prevent diesel generator sets from knocking cylinders.
(1) Correct and reasonable assembly, such as the mutual matching gap between the piston and the cylinder liner and the sealing gap of the piston ring. All kinds of mechanical equipment have clear regulations, and special attention should be paid when assembling.
(2) The mechanical equipment is used in strict accordance with the operating procedures.
Therefore, as long as the mechanical equipment is properly and reasonably assembled in accordance with the regulations, and the diesel generator set internal combustion engine is used in strict accordance with the operating procedures, the cylinder knocking phenomenon can be completely avoided.
Guangxi Dingbo Generator Set Manufacturing Co.,Ltd. is a diesel generator set manufacturer with more than 40 years of production experience. Its main brands include Yuchai generator sets, Cummins generator sets, Volvo generator sets, etc., and 64 sales and service departments nationwide. Users provide one-stop service of design, supply, debugging and maintenance. Welcome contact us by email sales@dieselgeneratortech.com
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