Piston Rings

Piston rings are metal rings located on the outside of the piston that provide a seal for the fuel and air mixture in an internal combustion engine. They also prevent oil from entering the combustion chamber from the crankcase. Most pistons contain three rings, two for sealing the combustion chamber (called compression rings), and one for keeping oil outside of the combustion chamber and returning excess oil to the crank case(called oil control rings). The rings are build with a gap that closes to allow for expansion due to engine heat.

Table of Contents

• 1. Usages
  • 1.1 Compression Seal
  • 1.2 Oil Control

Usages

Compression Seal

The primary purpose of piston rings is to seal the combustion chamber. The rings, called compression rings, are located near the top of the piston. There are generally two compression rings on a piston. The ring gaps are staggered so that any of the fuel/air mixture that escapes the first ring will be stopped by the second.

Oil Control

The oil control ring scraps the excess oil film off the cylinder wall and returns it to the crankcase.