One-Dimensional Modeling of Mechanical and Friction Losses Distribution in a Four-Stroke Internal Combustion Engine

Abstract

As the road transport accounts between 15%–18% of worldwide CO2 emissions, the automotive sector has a deep commitment to mitigate global warming. Consequently, stricter regulations have been adopted by the European Union and worldwide to reduce that big impact. Approximately, 10% of the energy generated by fuel combustion in the engine is destined to the auxiliaries components activation and the movement of mechanical elements with relative motion between themselves. A reduction on that figure or alternatively a mechanical efficiency improvement can be directly translated on target alignment. The aim of this work is developing a model to predict the mechanical and friction losses and its distribution in a four-stroke direct injection-diesel engine and simulating different strategies, which increment the engine efficiency. A 1D model has been developed and fitted in gt-suite based on the experimental results of a 1.6-L diesel engine. Additionally, a description of the tribological performance has been realized in different parts of the engine where friction is present. Finally, the engine friction maps have been broken down in order to quantify the friction losses produced in the piston ring assembly, crankshaft bearings, and valvetrain.

Investigation of friction properties in the piston-cylinder liner region of a single-cylinder compressed air engine using the GT-SUITE program

“…Oil film thickness is at minimum level in parts closer to TDC. 31 Together with the decrease in sliding speed in parts closer to TDC and BDC, asperity friction force increases. 32…”

Simulation and Analysis of the Impact of Cylinder Deactivation on Fuel Saving and Emissions of a Medium-Speed High-Power Diesel Engine

“…The pressure applying on the bottom surface is calculated using a blow-by model proposed in [48]. Hydrodynamic friction is modeled using the Reynolds hydraulic equation, and the contact friction between mental surfaces is calculated using the Greenwood-Tripp model [49]. The result analysis is conducted on steady state conditions.…”

A methodology to estimate mechanical losses and its distribution during a real driving cycle

“…Figure 9 shows that the mechanical losses distribution does not change a lot according to the temperature variation in the cycles when the engine stars in warm conditions, so, the effect of the reduced temperature variations can be neglected in this work. In the carried out driving cycles test, the initial engine cooling system temperature was around 90 o C. Subsequently and as developed in [25], individual maps of each pair of engine friction elements, including auxiliary losses, are used. These maps have been introduced into the software to obtain an estimation of frictional losses during driving cycles in terms of: Engine bearings, valvetrain, piston-ring assembly and auxiliaries.…”

“…In this work a model to estimate the lost friction energy of each element contributing to mechanical losses during a driving cycle measured has been developed. To do this, in a previous work [25] a model that is able to predict the energy consumed in the elements with relative movement was developed.…”

“…Before that, engine consumption map and specific fuel consumption map are shown in Figure 8 derived from previous work [25].…”