Browse Publications Technical Papers 2018-36-0133
2018-09-03

Power cylinder unit for medium & heavy duty diesel engines for emergent markets 2018-36-0133

In a Diesel engine, temperature reduction on a power cylinder unit (PCU) is an important demand due to increasingly engine load and performance of modern engines. Both piston and piston ring pack need to be prepared to attend this demand.
In general, Diesel engine pistons use cooling galleries to remove heat from high temperature regions and, therefore, reduce tensions on piston combustion bowl and bowl rim. Piston concept gallery was designed to improve piston performance: it consists on more efficient heat dissipation through an elevation of the gallery and new shape. The elevated piston promoted a temperature reduction of 39°C in the maximum temperature region without compromising product robustness and, thus, an improvement on lifetime prediction in 2 times in the piston combustion bowl region. Furthermore, a reduction on carbon build-up on ring belt region was also observed.
In parallel to the temperature and carbon build-up reduction, modern engines demand an improvement of lube oil and fuel consumption. Short- and long-term better results are achieved through piston ring pack design changes: top rings with reduced axial width and tangential load, 2nd rings made of nitride cast iron and smaller width bottom chamfers and oil-rings with reduced ring and land widths and high conformability and reduction of tangential load. These improvements are direct related to ring pack friction reduction both through area and load decrease and better oil scraping efficiency. Engine performance improvements achieved through PCU parameters combination.

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