The working surface of the taper ring is a tapered surface with a small taper (the taper ring cone angle of the 90 series diesel engine is 2°), and the cross section is trapezoidal. After the cylinder is installed in the ring, only the outer lower edge of the ring is in contact with the cylinder wall, which increases the contact pressure on the surface and improves the running-in and sealing performance. At the same time, the oil scraping performance is good when going down, and due to the "oil wedge" effect of the inclined surface when going up, it can float on the oil film and have the effect of evenly distributing lubricating oil. Therefore, although the contact pressure is high, it will not cause fusion wear.

 

When installing the taper ring, there is a direction requirement, and it must not be installed backwards, otherwise it will cause serious oil leakage (pump oil), increase the consumption of lubricating oil and carbon deposits in the engine. The correct assembly should be: the small end of the taper ring is installed facing upwards (the small end of the taper ring of the 90 series diesel engine is engraved with the word "上", if the mark of the old taper ring is unclear, the polished end of the outer circle should face down) . The taper ring is not suitable for the first air ring, because the first air ring bears a large combustion pressure. If it is used as the first air ring, it may be pushed away from the cylinder wall and lose its sealing effect.

 

2 Twisted Rings

 

The cross-section of the twisted ring is asymmetrical, and the upper edge of the inner circle of the ring is grooved (such as the second and third air rings of the 4125A diesel engine), or chamfered (such as all the air rings of the 4115T diesel engine) ; There are also grooves or chamfers on the lower edge of the outer ring of the ring. Because the section of the ring is asymmetrical and the elastic force is unbalanced, it will twist by itself after installing the cylinder. The outer surface of the ring is a tapered surface with a small top and a large bottom, which is in linear contact with the cylinder wall, and also in linear contact with the ring groove, and is close to the upper and lower end surfaces of the ring groove. This not only has good running-in and sealing performance, but also reduces the impact and wear on the ring groove, and the oil scraping and oil distribution performance is also better. The installation of the twist ring is the same as that of the taper ring, and there is also a direction requirement, and it cannot be installed backwards, otherwise it will cause the oil to run up. The inner grooved or chamfered side of the torsion ring should be installed facing up; the outer grooved or chamfered side should be installed facing down. The twisted ring is also not suitable for the first air ring. Like the taper ring, if the first air ring is used, it may be pushed away from the cylinder wall and lose its sealing effect.

 

3 barrel rings

 

The outer surface of the barrel-shaped ring is round and solitary after grinding, which is equivalent to the initial state of the rectangular section after running-in. After being installed in the cylinder, it is in line contact with the cylinder wall, and the up and down movements have the effect of forming an oil film. It has been strengthened at high speed and high horsepower. Widely used in the engine, as the first gas ring. The common ones are rectangular cross-section barrel rings, single-sided trapezoidal barrel rings or double-sided trapezoidal barrel rings. When installing, the side with the mark should face the top of the piston, otherwise it is easy to cause failures such as poor sealing, lower cylinder pressure, increased oil consumption, and difficulty in starting.

 

5 rectangular rings

 

Rectangular rings are also called flat rings, which are easy to manufacture, have a large contact area with the cylinder wall, and have a strong heat dissipation effect. They are currently the most widely used piston rings. It is easy to install, without anyway, it can be used as the first, second and third air rings. But when the piston reciprocates, it has the function of pumping oil, that is, once the piston reciprocates, the piston ring presses the oil in the ring groove to the combustion chamber once, and the oil is easily pumped into the combustion chamber. When the rectangular ring is mixed with the tapered ring or the twisted ring, the rectangular ring is used as the first gas ring.

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6 trapezoidal rings

 

The trapezoidal ring is often used as the first air ring of a diesel engine with a high load. It can change the gap between the ring and the ring groove when the piston swings left and right or the gap between the ring openings changes, thereby squeezing out the coke oil in it, which can It prevents the piston ring from being stuck due to gumming.