The piston ring is also called the rising ring, which is a vulnerable part of the compressor. Installed in the piston ring groove of the outer circle of the piston, the open ring of square section is made of gray cast iron, which has a certain elastic force. In the free state, the outer diameter is larger than the inner diameter of the cylinder. There are three types of slits in the piston ring: straight cut, bevel cut, and cut. The action of the piston ring uses its own tension to make the outer surface of the ring close to the cylinder mirror surface, and the end surface of the ring is closely attached to the wall surface of the piston ring groove to prevent gas leakage. To avoid leakage of pressure from the slit, the two piston rings The slits should be staggered from each other. The staggered angle is not less than 120° for sealing, and the piston ring also plays the role of oil and heat conduction.