Piston ring.
Piston Ring (Piston Ring) is used to embed the piston groove inside the metal ring, piston ring is divided into two types: compression ring and oil ring. The compression ring can be used to seal the combustible mixture gas in the combustion chamber; The oil ring is used to scrape excess oil from the cylinder. The piston ring is a kind of metal elastic ring with large outward expansion deformation, which is assembled in the profile and its corresponding annular groove. Reciprocating and rotating piston rings rely on the pressure difference of gas or liquid to form a seal between the outer circle of the ring and the cylinder and one side of the ring and the ring groove.
Piston ring function includes sealing, regulating oil (oil control), heat conduction (heat transfer), guidance (support) four roles. Sealing: refers to sealing gas, do not let the combustion chamber gas leakage to the crankcase, the gas leakage is controlled at a minimum, improve thermal efficiency. Air leakage will not only reduce the power of the engine, but also make the oil deterioration, which is the main task of the gas ring; Adjust the oil (oil control) : the excess lubricating oil on the cylinder wall is scraped off, and the cylinder wall is covered with a thin oil film to ensure the normal lubrication of the cylinder and piston and ring, which is the main task of the oil ring. In modern high-speed engines, special attention is paid to the role of piston ring control oil film; Heat conduction: the heat of the piston is transmitted to the cylinder liner through the piston ring, that is, the cooling effect. According to reliable data, 70 ~ 80% of the heat received by the piston top of the uncooled piston is dispersed through the piston ring to the cylinder wall, and 30 ~ 40% of the cooling piston is dispersed through the piston ring to the cylinder wall; Support: The piston ring keeps the piston in the cylinder, prevents direct contact between the piston and the cylinder wall, ensures smooth movement of the piston, reduces friction resistance, and prevents the piston from knocking the cylinder. Generally, the piston of the gasoline engine uses two gas rings and one oil ring, while the diesel engine usually uses two oil rings and one gas ring.
The correct installation method of the piston ring is as follows:
1. First need to install the oil ring, then the gas ring, the order is bottom-up;
2. When each ring is installed, the opening of the piston ring should not be extended too much, just enough to fit into the piston;
3. Install the combined oil ring:
Insert the liner ring into the piston oil ring groove, pay attention to the opening of the liner ring can not overlap; Install the lower and upper steel plates without using tools to open the openings. When installing, first clamp one end of the lower steel plate into the ring slot, press the steel plate opening position with your thumb, slide the thumb of the other hand into the ring slot along the side of the steel plate, and then load the upper steel plate in the same way. Do not install the upper and lower steel plates on one side of the liner ring; To avoid possible overlap of liner ring openings when the piston is pushed into the cylinder, stagger the upper and lower plate openings with the liner ring joints by 90 to 120 degrees. After installation, gently rotate the combined oil ring by hand, and it should be smooth without stuck.
4. Gas ring installation:
Use special tools to install two gas rings and one gas ring in turn, do not reverse the first gas ring and the second gas ring; When installed, the side is marked (HYR, HY, CSR, TLK, ALS, H, R, etc.). Should face up (piston head direction); Stagger the opening of the gas ring 180 degrees, do not turn the opening towards the direction of the piston pin.
5. Before assembling the piston ring into the cylinder, it is necessary to adjust the opening position of each piston ring.
Piston ring function:
1. Sealing effect
The piston ring can maintain the seal between the piston and the cylinder wall, and the leakage is controlled at a minimum, which is borne by the gas ring. Can prevent the cylinder and piston or cylinder and piston ring due to air leakage between the bite; It can also prevent failures caused by lubricating oil deterioration.
Step 2 Conduct heat
The piston ring can transfer and disperse the high heat generated by combustion to the cylinder wall, and can play a role in cooling the piston.
3. Oil control function
The piston ring can scrape the lubricating oil attached to the cylinder wall to maintain normal oil consumption, which is borne by the oil ring.
4. Supporting effect
The piston ring moves up and down in the cylinder, and its sliding surface is completely borne by the piston ring, preventing the piston from contacting the cylinder directly and playing a supporting role.
There are two types of piston rings: gas rings and oil rings. The gas ring is used to ensure a seal between the piston and the cylinder and to seal the compressed air in the combustion chamber. The oil ring is used to scrape off excess oil on the cylinder, which can prevent oil from escaping into the cylinder and burning.
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