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Along the last years, engine researchers are more and more focusing their efforts on the advanced low temperature combustion (LTC) concepts with the aim of achieving the stringent limits of the current emission legislations. In this regard, several studies based on highly premixed combustion concepts such as HCCI has been confirmed as a promising way to decrease drastically the most relevant CI diesel engine-out emissions, NOx and soot. However, the major HCCI drawbacks are the narrow load range, bounded by either misfiring (low load, low speed) or hardware limitations (higher load, higher speeds) and the combustion control (cycle-to-cylce control and combustion phasing). Although several techniques have been widely investigated in order to overcome these drawbacks, the high chemical reactivity of the diesel fuel remains as the main limitation for the combustion control.

The piston assembly is the major source of tribological inefficiencies among the engine components and is responsible for about 50% of the total engine friction losses, making such a system the main target element for developing low-friction technologies. Being a reciprocating system, the piston assembly can operate in boundary, mixed and hydrodynamic lubrication regimes. Computer simulations were used to investigate the synergistic effect between low viscosity oils and cylinder bore finishes on friction reduction of passenger car internal combustion engines. First, the Reynolds equation and the Greenwood & Tripp model were used to investigating the hydrodynamic and asperity contact pressures in the top piston ring. The classical Reynolds works well for barrel-shaped profiles and relatively thick oil film thickness but has limitations for predicting the lubrication behavior of flat parallel surfaces, such as those of Oil Control Ring (OCR) outer lands.

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).

Compressed natural gas (CNG) is a promising alternative fuel due to several main reasons, specially the strict engine emission regulations all over the world. This has made that lot's of cities have decided to use CNG as an alternative fuel in their urban transport fleets or in other urban tasks. Nevertheless, due to the recent implementation of the CNG technology in automotive sector, several problems related to lubrication have been detected, mostly affecting a reduction of the oil drain period and these problems showed no relationship with a particular fleet nor with the lubricant's brand used. These effects will have a very important weight on fleet manager's decision to select CNG as an alternative fuel, thus this reduction does not only increase the cost in engine oil, there are other maintenance actions referred to this basic period of oil drain, thus also increases other more significant costs.

Low viscosity engine oils are considered a feasible solution for improving fuel economy in internal combustion engines (ICE). So, the aim of this study was to verify experimentally the performance of low viscosity engine oils regarding their degradation process and possible related engine wear, since the use of low viscosity engine oils could imply higher degradation rates and/or unwanted wear performance. Potential higher wear could result in a reduction in life cycle for the ICE, and higher degradation rates would be translated in a reduction of the oil drain period, both of them non-desired effects. In addition, currently limited data are available regarding “real-world” performance of low viscosity engine oils in a real service fleet.

Pure biodiesel is non-toxic, biodegradable and greenhouse gas neutral alternative fuel with potential successful future but reduced quantitative information is available about the impact of biodiesel on engine durability and long period usage effects. In this study, a commercial light duty Diesel engine installed on an engine test bench has been operated fuelled with pure biodiesel (B100 referred to the EN-14214 standard) during a period test of 300 hours in order to analyze engine performance and components behavior. A engine characterization has been completed using conventional diesel fuel (EN 590). Then, following a specific defined operation cycle and fuelled with pure biodiesel, a study over different engine components such as: engine oil, fuel filters, Diesel Particulate Filter (DPF), so on, has been done in order to obtain possible negative effects and modifications required over maintenance policies applied to them.

This paper is structured into two different parts: Firstly, it describes a methodology to evaluate wear conditions in internal combustion engines in order to go beyond the classical evaluation based on specified wear concentration limits provided by engine manufacturers or commercial oil laboratories. The proposed methodology uses spectrometric wear debris measurement data and typical maintenance data to obtain a more representative parameter of wear condition, defined as “compensated wear rate”, that takes into account particular engine operating conditions affecting wear concentration measurements. Later, an evaluation of this compensated wear rate is carried out using statistical criteria and considering individual engine characteristics such as engine age, type of service, engine metallurgy, environmental conditions of work etc.

This paper reports the results obtained in the ECOBUS Project. This project has been supported by the LIFE Program, one of the spearheads of European Union's environmental policy. The main aim for this project was to convert used cooking oil into biodiesel and then use this biodiesel in urban buses, contributing to reducing in one hand waste cooking oil that can create problems in the drainage city system and water contamination and on the other hand reducing engine polluting emissions. Departamento de Máquinas y Motores Térmicos (DMMT) facilities at the Universidad Politécnica de Valencia (Spain) were used to conduct detailed performance and emission measurements in a Diesel engine similar to those used by the urban transport operator in Valencia (Empresa Municipal de Transporte, EMT). The test engines were operated with conventional Diesel fuel (EN 590) and three different biodiesel blends: 30, 50 and 70%, using the pure biodiesel obtained from used cooking oil (EN 14214).

Decreasing fuel consumption in Internal Combustion Engines (ICE) is a key target for engine developers in order to achieve the CO2 emissions limits during a standard cycle. In this context, reduction of engine friction could help meet those targets. The use of Low Viscosity Engine Oils (LVEOs), which is currently one of the avenues to achieve such reductions, was studied in this manuscript through a validated numerical simulation model that predicts the friction of the engine’s piston-cylinder unit, journal bearings and camshaft. These frictional power losses were obtained for four different lubricant formulations which differ in their viscosity grades and design. Results showed a maximum friction variation of up to 6% depending on the engine operating condition, where the major reductions came from hydrodynamic-dominated components such as journal bearings, despite an increase in friction in boundary-dominated components such as the piston-ring assembly.

This paper presents a study and review of the data collected in an Engine Fault Diagnosis System using oil analysis, used for diagnose different industrial vehicle engines (trucks, buses, road construction equipment, etc.). This system is being used since the beginning of the 1990s decade. The information acquired in this system has generated an important database that collects the information about the oil status at drain moment and further collateral information. Knowledge about oil properties (viscosity, TBN, detergency), and oil contamination, (insolubles content, soot from combustion, fuel dilution, and water) during engine operation, provide an important information about lubricants efficiency, optimal drain period and engine status that it has a direct influence on vehicles running cost. The study has been performed with a statistical tool which allows the characterisation of the main parameters of oil behaviour, in addition to the relationship between them.