Cylinder pulling of diesel generator set refers to the obvious longitudinal mechanical scratches and scratches on the inner wall of the cylinder within the range of movement of the piston ring, causing melting and abrasion in severe cases, causing the problem of starting the diesel engine or extinguishing itself. Cylinder pulling of diesel generator set is a serious accident.
The root cause of cylinder liner drawing is that it is difficult to form an oil film between the inner wall of the cylinder, the piston ring and the piston, resulting in poor lubrication and even dry friction. There are many specific reasons for this situation, which can be summarized into two aspects:
1. Reasons for the cylinder liner
The roundness and tolerance of the cylinder liner exceed the allowable range, greatly reducing the sealing performance of the piston and cylinder liner. The high-temperature gas in the cylinder rushes down, and the oil film between the piston and the cylinder wall is destroyed, causing the cylinder to be pulled out.
The cylinder liner was deformed during assembly. For example, if the protrusion of the upper end of the cylinder liner is too large, the cylinder liner will be deformed after installing the cylinder head; the water-resistant ring of the cylinder liner is too thick, and the pressure enters the cylinder block to cause the cylinder liner to deform, which can easily cause the cylinder to pull.
2. The reason for the piston group
The piston ring clearance is too small. If the opening gap, side gap or back gap of the piston ring is too small, the piston ring will be trapped by thermal expansion and tightly clamped with the cylinder wall, otherwise the piston ring will break and it is easy to pull out the groove on the cylinder wall.
The piston pin came out. Because the piston pin circlips or falls off, it is not broken, and the movement of the piston pin easily strains the inner wall of the cylinder, resulting in the crankcase of the cylinder. The piston is too small or too large. If the piston material is not good, the manufacturing size error is too large, or the piston is deformed after the piston pin is assembled, which causes the matching gap between the piston and the cylinder to be too small, and the piston is stuck after thermal expansion, and then the cylinder wall is pulled out.
The piston ring is scorched. Excessive carbon deposition can cause the piston ring to stick or seize in the ring groove, while carbon deposition is a hard abrasive that will be ground into longitudinal grooves on the cylinder wall. Serious eccentric cylinder piston. Due to the bending and distortion of the connecting rod, the deviation of the parallelism and coaxiality of the connecting rod daily, main journal, and piston pin is too large, resulting in obvious cylinder piston, which will accelerate the worn piston ring, piston and cylinder wall, and destroy the formation of oil film .
The air filter is not sealed, which makes the filtering effect worse, and impurities such as dust and sand enter the cylinder and form abrasive wear. Tests have shown that if a few grams of dust is inhaled every day, the wear of the cylinder liner will increase by more than 10 times.
After changing the diesel engine, the cylinder liner, piston and piston ring. There are many uneven surfaces on the surface of the micro-parts, which makes it difficult to form a lubricating oil film. If the operation is not put into use immediately, it is easy to cause accidents such as cylinder drawing.
It usually starts at low temperatures. When the engine is started at low temperature, the lubricating oil has high viscosity and poor fluidity, and it is difficult to form an effective oil film on the inner wall of the cylinder. According to the experiment of the research department, when the cooling water temperature is lower than 30℃, the wear rate of the cylinder liner and other parts is 5-7 times of the normal water temperature. The engine is overheating. Poor cooling system maintenance, or overload operation, the high temperature machine not only reduces the mechanical strength of the parts, and the cylinder wall can not form a lubricating oil film. Pistons and other components can easily get stuck in the cylinder liner after heating and expansion. The result is often that the piston partially melts and the inner wall of the cylinder liner is pulled out, forcing the engine to stall.
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