Piston rings in internal combustion engines

The design of the internal combustion engine (ICE), contains a great amount of detail. Without most of them are motor simply becomes unworkable or ineffective. These details include, and piston rings. That's about it, and go today, discussed in the article "Piston rings in internal combustion engines." For more efficient use of energy gases when burned fuel / air mixture, maximize the seal a couple of "piston-cylinder. Since the size of pistons and liners are changed due to the difference in temperature when the engine (top or bottom of the cylinder, hot or cold engine), reducing the gap between these parts to zero can lead to what is being heated, with a dense fitting pistons and cylinders can jam. This task is decided by increasing the gap between a piston and cylinder set a special sealing element - slotted elastic, so-called piston rings. These rings in internal combustion engines have three important functions. First, provide the best possible sealing of the combustion chamber. This prevents the penetration of gases into the crankcase, optimizes energy usage of gases affects the characteristics of the motor (power, torque, fuel consumption). Secondly, with the help of the Rings removes heat from the piston to the cylinder surface, which cools the fluid, or airflow. Third, they serve to optimize the lubrication of working surfaces of parts of the cylinder-piston (pistons, rings, sleeves). To effectively meet these challenges, one ring can not do, so the piston rings, worn a few - from one to four (usually - three). In such multiring design to serve as distributed: a compression ring "instructed" sealing and heat rejection, and butter-swap - cylinder lubrication. What keeps the compression? Ring on the piston are located nearby, but they have to work in different environments, and hence the requirements for their properties differ. The largest load is carried by the top ring. It can withstand very high temperature (200-250 ° C) and considerable pressure gas (5,5-6,0 MPa), opposes the chemical effects of combustion products, working with inadequate lubrication (zone TDC remains practically free of grease, a thin oil film can easily be prodavlena due to lower velocity of the piston near top dead center). For this reason, the upper rings are made of high strength materials - cast iron (gray and black) and the steel alloyed with nickel, chromium or molybdenum. In addition, the working surface of the Rings electrolytically applied durable coating such as chromium, molybdenum, chromium, molybdenum, chromium-ceramic. High-strength composite coatings are just using the plasma spraying. Both upper and lower rings of the same subject phosphating or nitriding. The second compression ring works in less severe conditions - at a lower temperature and pressure. In this connection, it is inappropriate to give him a higher wear resistance as the top. It is made more lenient, resulting in less wear of the cylinder liner, through this increases their service life. In addition to compression, the second ring, often performs and oil-swap function. To do this, its profile is given a special form. For the manufacture of compression rings used iron and steel, as well as cermets. Metal-ring is produced in our country, but to find them for sale very easy. You need to add a few words about the thickness of compression rings. First, it ranged from 1.75 to 2.0 mm (at top) and 2,0-2,5 mm (at the bottom), but in modern engine construction that has begun to reduce their thickness (top to 1,2-1,5 mm, bottom up 1,75-2,0 mm), in order to reduce their weight. In this way, designers are trying to reduce power losses due to friction and overcome inertia forces, reduce wear, increasing the resource engine. It also aims to reduce the appearance of scratches and overheat when they were run. Than metered lubrication? Oil-removable rings are designed to prevent penetration of oil into the combustion chamber and for dispensing quantities of oil remaining on the cylinder walls, and determining conditions of normal operation of the piston and compression rings, and also affects engine performance and speed of wear. These rings are made whole and teams, consisting of several parts such as expansive spring and one thick profiles, or two thin flat ring. In the past, oil-removable ring made mostly of whole-iron, but now their place was taken by prefabricated steel. Production of prefabricated rings are cheaper, they are 1,5-2 times lighter than cast iron, are more reliable, durable and efficient, due to a better fit to the walls of the cylinders. These rings and their spring-extender made from stainless or carbon steel. To improve the durability of the working surface of the oil-removable rings as well as compression, they put a layer of chromium. Additionally treated (polished, polished, chrome plated) and spring-extender. Is it all that simple? After such a brief acquaintance with the design of piston rings in internal combustion engines, certainly seem that this feature does not produce enough hard. But this view is mistaken. The proof is a curious fact - the world's leading manufacturers of these rings are rejected up to thirty percent of production. This is due to exceptionally high standards to all, without exception, the characteristics of these small details. Quality piston rings tested on many indicators - the hardness, the geometry (shape, size) elasticity, the quality of treatment and coating. It should be noted that some manufacturers of rings from the CIS rejection rate is even higher, and this here is of poor quality products are often illegal ways goes on sale. Kompressionniki. Features common designs. Cylindrical working surface (rectangular section). The oldest design that requires a long period of running-in, which leads to increased oil consumption, carbon-formation and smoke from the breather. Beveled top and bottom plane. Feature of this design reduces the tendency of the Rings to the occurrence as a result of increased soot formation. They are used as the upper compression ring, most often in diesel engines. Cones or cylinders with the lower outer neck (drag). They are used to improve lubrication of moving the piston to top dead center (cones), and for better removal of oil when the piston moves toward bottom dead center. Often referred to as combined, because of their dual role - an oil-removable and compression. Cylinders or cones with an inner top notch. Twisting in the transverse plane and hugging the wall of the cylinder of one edge, such rings are relatively quickly burnished. But the removal of heat from the piston is worse due to the reduced contact area of ??the ring with the surface of the cylinder. Such rings are less susceptible to transverse vibrations, rather than the "minute". Can act as, both the first and second compression ring. Wholly or partly conical working surface. Such rings are characterized by an accelerated burn-in and low oil consumption during break-in, due to the high specific pressure on the cylinder wall. Often referred to as "minute." Most often they are used as a second compression rings, rare - the first place. Cones with inner lower neckline. This design of the reverse twisting "for faster running-in and touching the upper inner edge of the groove, prevents penetration of oil in nadkoltsevoy volume. These rings are used as the second compression. The coated cylinder. They are often called "bimetallic" - in order to increase engine life working surface of the ring is covered with anti-friction wear-resistant material (chrome, chrome - ceramics, molybdenum). Most often this way improves the upper compression rings. Maslosemniki. Features common designs. Slotted. The earliest one-piece construction with external projections of cylindrical shape and drainage holes in the center. Their small radial pressure, and poor adaptability to the geometry of unevenly worn cylinders. For modern engines are rarely used. Slotted with chamfered. Chamfers are made from cylindrical outer edges (the options from different angles). There are both solid, and with the coil spring-expander as a supplement. On the working edge is sometimes applied to wear resistant coating. Teams. Represent two flat steel ring with a U-shaped spring-expander, set between them. Working edge may be covered with a layer of chromium. Protective coatings. Properties. Chrome plating. Inflict electroplated hard chrome plating exhibits high antifriction properties and wear resistance, resistance to different burns. Tests showed that the wear of upper compression rings with chrome-plated, 50%, reducing wear of the working surface of the cylinder. Using solid or porous chrome plating. Accumulating a reserve of oil in small pores, promotes anti-friction properties and reduce wear. Phosphating and ferro-oxidation. These methods cover the rings are chemical or thermochemical. In the case of phosphate, the surface is covered with phosphate crystals, and ferro-oxidation - iron oxide. Phosphate layer wears out faster than the base material, reducing the time burnishing. And thanks to the solid particles of iron oxides gives the effect of "lapping paste. Phosphate and ferro-oxide coatings, along with the nitrided layer, resistant to burns in the case of overheating. Nitriding. In the process of thermochemical treatment at 500 ° C, the surface becomes saturated with nitrogen and carbon. Such a method is applied to achieve improved wear resistance of the Rings, and is most often used to improve the technical performance of steel rings with a high content of chromium.