Abstract
Increased power (pme 30 bar - pmax 250 bar) longer life expectations up to 40000 h running hours together with low oil consumption of 0,3 to 0,4 g / KWh these are the future demands for piston rings for high output Diesel engines.
Key words: Compression rings, oil control rings, ring materials, oil consumption and ring dynamics, ring pack applications, anti-polishing ring
1. INTRODUCTION
The direction of engine development is to a great extent driven by economic and competitive forces towards reducing the whole life costs of the engine. Legislation and environmental awareness have brought exhaust emissions into prominence. The engine development agenda therefore includes the following items:
Service life
Specific output
Heavy fuel quality
Fuel consumption
Lubricating oil consumption
Exhaust emissions
The trend in specific output is shown in (Fig. 1) in terms of brake mean effective pressure (Pme), the rising trend of which continues unchecked with 30 bar already in production very soon. The maximum cylinder pressure and thermal loading of the cylinder components increase as a direct consequence, the former also being increased in the pursuit of lower fuel consumption so that 250 bar is not unusual any more.
Hot combustion processes for increasing the output of combined steam turbines are making also the life of the piston rings more difficult. Together with todays usual heavy fuel oil qualities the demands on the system piston, piston rings and cylinderliner are increased dramaticaly.
Fig. 1 Mean Effective Pressure of Four-Stroke Medium speed Diesel Engines
