What Is a Piston Ring?
Piston rings are the parts necessary for a car engine to work efficiently.
They exist between the piston and cylinder, to prevent fuel gases from leaking out of the piston and cylinder. Piston rings also play a variety of other roles, such as acting as a lubricant to prevent deterioration caused by hot gases that come into contact with the piston and cylinder, keeping heat out, and preventing the piston from hitting the cylinder. Piston rings are an important component in the operation of a car.
Uses of Piston Rings
Piston rings are used in cars. Their main role is to prevent combustion gas leakage. When combustion gases leak, engine oil deteriorates faster.
Piston rings cannot completely prevent this because they expand due to the hot combustion gases, but piston rings exist because they have a purpose other than preventing combustion gas leakage.
Piston rings are a set of three rings, called top ring, second ring, and oil ring from the top, and they are attached to the piston in an overlapping manner.
Principle of Piston Rings
Piston rings are a set of three rings, of which there are two types
1. Compression Ring
Compression rings are used to eliminate the gap between the piston and cylinder and prevent gas leakage. It consists of two pieces: a top ring and a second ring.
Top Ring
The top ring is often a barrel face type, which has a solitary sliding part that hits the cylinder. This reduces wear with the cylinder.
Second Ring
Taper face type or undercut type is often used for the second ring. The tapered face type has a structure in which the sliding parts make contact, not with the surface but with a line, which makes it easy to lift the ring when it rises.
The undercut type has a structure in which the lower side is cut off. This type also makes linear contact with the cylinder surface during ascent, enabling smooth movement.
2. Oil Ring
The bottom layer uses an oil ring to control the thickness of the engine oil on the cylinder wall. The oil ring consists of two rings called rails sandwiched between spacers that have a discrete structure.
The role of the oil ring is to control the thickness of the oil film that forms between the rail and the cylinder wall. If this oil film is insufficient, a phenomenon called scuffing occurs, which causes damage to the cylinder.
These piston rings are attached to the piston. Therefore, they move back and forth more than 10,000 times per minute at the same time as the piston. By producing a moderate adhesion force, they are able to smoothly move back and forth within the cylinder without pressure changes occurring.
Since it is one of the parts that work in contact with combustion gas in the engine, it is important that the material be able to withstand high temperatures and wear. For this reason, cast iron and steel are used. Recently, however, steel, which has high wear resistance, is often used.
Other Information on Piston Rings
Functions of Piston Rings
1. Combustion Gas Seal
The cylinder wall and piston rings seal the gases generated during combustion to prevent them from leaking into the cylinder.
2. Engine Oil Control
A film of engine oil is created on the cylinder wall to prevent the cylinder and piston from being scratched, a phenomenon known as seizure. The thickness of this film is adjusted by the Piston Rings. In addition, the piston rings play a role in preventing excess engine oil from entering the combustion chamber.
3. Heat Transfer Function
The heat transfer function is responsible for releasing the heat generated by the gas explosion. It prevents the engine from overheating by releasing heat from the top of the piston to the Piston Rings and from there to the cylinder.
4. Piston Posture Support
This function prevents the piston from hitting the cylinder. The piston rings allow the piston to move smoothly, even when the piston is in an oblique position.