Structure And Function Of Piston Ring Of Diesel Generator Set

Piston ring is an important part of the piston connecting rod assembly of diesel generator set. The piston connecting rod assembly is used to transmit the power obtained in the combustion process to the crankshaft. When the bearing is placed in the cylinder, the engine is working. The reciprocating motion is transferred to the crankshaft and converted into rotational motion. Today we will take a look at the structure and function of the piston ring of a diesel power generation unit.

1.The structure of the piston ring.

Piston rings are usually made of alloy cast iron, and their hardness is generally greater than that of the cylinder wall. In some engines, in order to improve the wear resistance of the piston ring, the working surface of the first ring is plated with porous chromium. The names of the parts of the piston ring are shown in the figure below. The diameter of the piston ring refers to the outer diameter of the cylinder in the compressed state (in the automatic state, the outer diameter of the ring is larger than the cylinder diameter). The upper and lower planes of the piston ring are called the end faces, the distance between the end faces is called the ring height, and the gap between the ring height direction and the ring groove is called the backlash, the outer surface of the ring is called the working surface, and the inner surface of the ring is called the back surface. The gap between the surface direction and the ring groove is called the back gap, the ring gap is called the opening (also called the opening gap). Under the condition that the ring will not swell and die after being heated. The opening gap should be as small as possible.

The opening shape of the piston ring can be divided into straight, oblique and stepped shapes, as shown in the figure below. The size of the opening gap of the piston ring will affect the sealing effect, and the sealing effect has a certain relationship with the opening shape of the ring. In the case of the same opening to the gap, it is generally considered that the oblique and stepped sealing effects are better. However, it is found from the test that no matter at no load or full load, the amount of air leakage has little relationship with the shape of the opening. In addition, the straight opening shape ring is easy to process, so most internal combustion engines now use straight opening piston rings.

2.The role of piston rings.

Piston ring is a metal split ring with elasticity, which can be divided into gas ring and oil ring according to its different functions. The gas ring is installed in the gas ring groove of the piston head to prevent high-pressure gas from entering the crankcase from the cylinder and play a sealing role. Most of the heat absorbed by the piston crown is transferred to the cylinder wall through the air ring, and then taken away by the cooling water in the water jacket, so the air ring also plays a role in heat transfer. The oil ring is installed in the oil ring groove below the gas ring to distribute the oil on the cylinder wall to reduce the wear of the piston and the cylinder wall. At the same time, the excess oil on the cylinder wall is scraped down and flowed back to the crankcase to prevent the oil from getting into the combustion chamber.

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