When the piston compressor is running and starting, when the piston reaches the inner and outer (or up and down) stop point, it will directly or indirectly collide with the end face of the cylinder, which is called "hitting the cylinder ". Hitting the cylinder will cause serious damage to the cylinder, piston, piston rod, piston pin, cross head and a series of machine parts. Therefore, high vigilance should be aroused to prevent such accidents from happening.
There are usually several reasons for hitting the cylinder:
1) during the operation of compressor, the relative position of piston and cylinder changes due to various reasons. When this change is greater than the gap left in advance between piston and cylinder head, the direct impact between the cylinder head and the piston will occur. For example, if a factory ZY-33/30-I type oxygen compressor, the stop cone bolt head at the joint of the second-level cross head and piston rod is worn, which makes the piston rod loose and move up, it caused a serious accident that the piston collided with the cylinder head, which broke the secondary piston and the secondary cross body. Therefore, during the overhaul and installation, all kinds of gaps which can affect the position of the piston should be paid strict attention to to avoid hitting the cylinder due to the movement of the position of the piston.
2) a large amount of cooling water or lubricating water (for the old-fashioned oxygen compressor) entering the cylinder will cause indirect impact between the piston and the cylinder head, and the impact of the cylinder caused by this reason is also called "hydraulic accident ". This kind of accidents mostly happen in the process of driving. For example, the 2-20/20 type oxygen compressor of a factory does not close the lubricating water valve during the first stop, which makes the lubricating water flow into the suction pipe from the valve chamber and accumulate in large quantities, when restarting, it was not well checked. After driving, the water in the inhaled pipe entered the cylinder through the suction valve along with the oxygen. Hydraulic accident occurred when compressing, with a loud noise, the whole cylinder is pushed forward by the piston, the middle seat is broken, the foundation is broken, the piston is broken, the piston rod is bent, and the compressor is seriously damaged.
There are many factors that cause water inflow in the cylinder, for example, the lubricating water valve is not closed when parking, and the lubricating water accumulates; the cooling water between the cylinder jacket and the cylinder jacket. The sealing of the rubber ring is not strict, and the cooling water leaks in a large amount when parking; the intermediate cooler leaks, and the cooling water leaks into the suction pipe in a large amount when parking; sometimes the leakage of the cooling water sleeve of the air seal will also enter the cylinder.
In order to prevent hydraulic accidents from happening, in addition to maintaining the equipment well and blocking all the loopholes, you must check the car before starting. If you are not sure, you can unload the two air valves at both ends of the cylinder to blow off, and then start the cylinder formally after ensuring that there is no water in the cylinder.
3) foreign matter enters the cylinder, causing indirect impact between the piston and the cylinder head. It is common that the broken valve plate of the air valve, the center Bolt and the valve seat fall into the cylinder. The harm of breaking the valve plate is still small. If the center Bolt or the valve seat falls into the cylinder, it will cause the serious accident of breaking the piston or the cylinder head. However, there are always some signs before this kind of accidents happen, because foreign matters come from the air valve, and the damage of the air valve must be firstly reflected in the exhaust pressure at all levels. When the change of exhaust pressure at all levels is found, and this change is caused by the abnormal operation of the air valve, it should be repaired timely. In the process of overhaul, it is also necessary to prevent foreign matters from entering the cylinder. Turn the car before starting. During the operation, pay attention to the working condition of the air valve at any time and listen to whether there is any abnormal noise in the cylinder to prevent the accident of hitting the cylinder.
