Optimization Design Of Piston Rings In 4G6 Engine

To reduce air pollution and prevent the greenhouse effect, the new technology which can reduce the pollutant of exhaust air especially CO2 and improve the fuel economy are highly concerned. Since 1970's, the emissions regulations and fuel consumption regulations are gradually improved, under these circumstance, our country established strict pollution regulations and fuel consumption regulations. In these regulations not only improved all the limit levels, but also changed the test procedures, and at the same time engine performance are improved too. So, high compression ratio and low friction are the research direction of gasoline engine, this need to redesign the piston rings to satisfy all these demands.The optimization of the piston rings not only have to meet the normal requirements, but also to achieve the engine light weight, to reduce the friction factor between the piston rings and the cylinder surface and to improve the mechanical efficiency , and then to improve engine performances,at the same time it also needs to reply the corrosion problem from the EGR.This paper is aimed at the characteristics about high performance, low emission and low fuel consumption of the improved engine. To meet the requirement of the piston ring, spread a deep study in the structure parameters and surface treatments on how to improve piston ring intensity, the seizure resistance, the wear resistance and reduced friction loss, main work in this literature includes:1. The outward pressure of piston ring and ring's width are confirmed to make sure of its low tangential force and light weight so that to decrease fuel comsuption.2. Piston ring free gap and its wall of major parameters are obtained to make sure of its use.3. The cross section of pistion ring is properly selected; its bearing capacity may be great during all service life.4. Piston ring materials is selected to meet need of strength of piston ring, meanwhile, laid foundation for PVD treatment.5. Check the conformability and strength of the piston ring to ensure that the new design to meet the requirement.6. The surface treatment can enhance corrosion resistance of piston ring and improve wearing resistance of piston ring especially when it's running at first stage, and that the life of piston is prolonged. The quality of surface treatment can satisfy the demand of seizure resistance, so that the problem of scuffing can be solved. So, to satisfy these demands, PT14 and Telfon treatment are used on the top ring, entirely parkerising treatment are used on the second ring, PT11 treatment are used on outer circumference of siderail to enhance it's wearing resistance and entirely parkerising treatment are used on spacer.7. It was compare with the sample of the engine what improve the piston ring and the old engine, and check the optimize design ring on the engine though the durability test.It is prove that not only get the result of require target value, but also piston ring scuffing was much smaller than it was after durability test, the oil consume of the engine and the blowby wasn`t change to bad.It is prove that optimize design ring could satisfy requirement when we use.For the requirements of the improved engine reduce the piston rings' tangential force and improve the surface treatment and other means were taken to the success of research, and get the following conclusions:1. The piston ring's tangential force has a big influence on the engine fuel consumption, the lower the force, the better fuel consumption, but it has adversely affected to the oil consumption;2. Even if some ones'tangential force higher than before, but as long as the compound piston ring's tangential force lower than before, the fuel consumption will reduce;3. The top ring's outward pressure plays a vital role to the gas sealing. The greater pressure, the better the effect of sealing;4. The piston rings'tangential force lies on the piston ring's surface pressure and the ring's width, even the surface pressure maintain unchanged, lower the ring's width can also achieve the tangential force lower;5. LOC is good or bad depends on the conformability K of the piston ring, in particular the conformability of oil ring, the greater the K value, the lower the LOC, even lower the tangential force;6. Piston ring end clearance of the second ring and the volume between the second ring and piston can influence LOC, piston ring end clearance is reduced and then LOC will be better, when the second ring and the volume between the second ring and piston is fixed, but piston ring end clearance of the second ring can not smaller than piston ring end clearance of the top ring.7. Free gap, in addition to taking into account its impact on the of tangential force piston rings, we must also consider the impact of their stress, if free gap increased, the corresponding increase of stress; if the free gap decreases, the fitting of stress increased.8. The choice of the piston ring's wall should be fully aware that with the increase of wall, the piston ring fitting stress and work stress has been clearly increased; deformation and breakage have also increased. So when conducting piston ring design should minimize the piston ring's wall.9. The functions of second ring is gradually weakening, tend to cancel in second ring.10. PVD ceramic coating on piston ring surface has higher wear resistance, seizure resistance, corrosion resistance and lower friction coefficient than gas nitriding and chrome plated; it is a new trend of piston ring surface treatment.11. If hardness is same, the wear resistance of PVD ceramic coating depends on the coating thickness, the deep the coating thickness, the higher the wear resistance.12. The running in first stage on the piston rings has a major impact on service life. The shorter the running in first stage, the longer its life, and Teflon treatment can effectively shorten the running in first stage.