Search Results

In the present work, a system approach to the tribological optimization of passenger car engines is demonstrated. Experimental data and simulation results are presented to demonstrate the role of surface specifications, ring pack, and lubricant on the piston/bore tribology. The importance of in-design “pairing” of low-viscosity motor oils with the ring pack and the cylinder bore characteristics in order to achieve maximum reduction in GHG emissions and improvement in fuel economy without sacrificing the endurance is elucidated. Earlier motored friction data for two different gasoline engines - Ford Duratec and Mercedes Benz M133 - using motor oils of different viscosity grades are now rationalized using AVL EXCITE® piston/bore tribology simulations. The main difference between the engines was the cylinder bore surface: honed cast iron vs thermally sprayed, and the valve train type: direct-acting mechanical bucket (DAMB) vs roller finger follower (RFF).

Motivated by the demand for the reduction of fuel consumption, in particular to meet the engine energy efficiency goals of the Brazilian incentives legislation (INOVAR AUTO), this paper proposes a method to identify potential for energy efficiency and exemplifies it through three engines of the Brazilian market. The proposed method consists in identify the engine losses in different operating points (speed x load) through combustion mapping and the basic formulations which describe the energy/losses share. These data are grouped into 12 map sections, allowing the identification of the ones with more improvement potential. The baseline engine is 1.6 l naturally aspirated, port injection and was tested with E100 fuel (100% Ethanol). Engine #2 is similar to the baseline but with 4 valves per cylinder and a lower viscosity oil. The engine #3 is a more advanced engine: turbo charged, direct fuel injection, variable valve train and piloted pumps.