The fire ring effectively reduces bore polish of the cylinder liner by scraping down carbon adhering to the top of the piston head, thereby maintaining the inner cylinder liner surface in good condition over a longer period. It was therefore considered possible to reduce partial cylinder liner wear and maintain proper sealing between cylinder liner and piston rings, thus reducing consumption of lubricating oil.
In a 1000-hr shop test, we recorded an extremely low rate of lubricating oil consumption of 0.2 g/kW・h, with no negative indications such as piston and cylinder liner scuffing or other forms of abnormal wear.
A bonito fishing boat fitted out with a 6MG28HLX engine. The first engine in the 28HLX series, has remained in good running order after more than 6000 hours of operation within a year, even under the severe conditions peculiar to bonito fishing boats, such as sudden load changes from 0% to 100%. Even under such circumstances, the engine's lubricating oil consumption (LOC) is extremely stable (Fig.7), with the BN and viscosity of the lubricating oil remaining stable.
An inspection after one year in operation revealed that the engine is still in excellent condition, with very little carbon adhering to the piston top-land (Fig.8), and even honing traces clearly visible on the cylinder liner. (Fig.9)
6. CONCLUSION
The new medium-speed engine series described above are now being marketed. Those that have been in service are operating in good order, even after more than 8000 running hours.
We are confident that this product, in combination with our alliance with the General Electric to promote sales, will further increase our share of the medium-speed diesel Engines market.
7. REFERENCES
[1] Diesel & Gas Turbine Worldwide Catalog 1999 VOL.65 (2000)
[2] M. Kawakami, ET AL.: Environmental Control Of Advanced Medium Speed Engines, 20TH CIMAC 1993
[31 H. Nagasawa ET, AL.: Development Of Ultra High Power Four-Stroke Engine For High Speed Vessel. 22ND CIMAC 1998
[4] W.J. Griffiths, ET AL.: Piston And Ring Technology For Medium Speed Diesel And Gas Engines. 1996
[5] J. Graham Howard: Development Of MB430 Engine To Reduce Lubricating Oil Consumption, ICE-VOL. 27-1, ASME l996
