You may know,in order to reduce wear and increase the life of piston grooves in high speed engines,a ferrous metal rings are inserted into the grooves.Below,you will find detail description of piston ring used in Internal Combustion Engine.This information is useful and valuable for every mechanical or automobile engineer or automobile owner.
The piston rings,which are also called as compression rings are fit closely in the grooves provided in the piston.These rings are worn out before the wearing of the piston and cylinder wall.Hence by replacing the same,we can avoid replacement of piston or cylinder.
The leakage of the high temperature gases produced during power stroke in the combustion chamber are prevented by piston rings.The piston rings form an effective seal and at the same time transmit heat from crown to the cylinder walls and hence keep the temperature within the workable limit.
There should be at least two piston rings in each piston of internal combustion engine.For the higher capacity engines,there are four or even six piston rings have been used.The number of rings are depend upon the capacity and size of the I.C.Engine.
In order to achieve the effective seal against lubricating oil and high pressure gases leakage,a great pressure must be exerted ,by each ring on the cylinder walls.To produce this effect,the rings are made slightly larger in the diameter than that of cylinder bore and cutting small gap which is partly narrowed when the ring is fitted.The end gap in the piston ring provides flexibility to the ring and the same time allowing for thermal expansion.
There are another rings used in piston grooves,called as, Oil Scraper Rings.The function of these rings are,only as much quantity of the oil as it just sufficient to maintain proper lubrication is allowed to reach the skit.The excess oil which would have leaked in the combustion chamber without serving any useful purpose and rather leading to carbonization,is scraped off by the oil scraper ring.
While mounting the piston rings over the piston,a great care should be taken to ensure that the gaps of various rings should not fall in the same vertical line.
The piston rings of internal combustion engines are made in various section such as,standard,tapered,grooved,wedge and L shape.Where as oil scraper rings are made as,narrow,wide,tapered and six segment cord section.
The cast iron along with 2.5% silicon will provide a good wear Resistance to piston ring.In case of passenger cars,the piston rings are usually plated with Chromium Tin or Cadmium.The plating reduces the rate of cylinder wear and hence increase the life of internal combustion engine.
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