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Nowadays, the use of numerical simulations is an important tool in order to optimize the engine and components behaviors, directly contributing to the emissions and lead-time development project reduction. With the increase of engine thermal specific loading, excessive piston carbon build-up may be an issue, eventually causing liner polishing and excessive Lube Oil Consumption (OC). During the development of a Cummins heavy duty 8.9L engine, preliminary engine test results indicated excessive OC levels, above the engine specification limits. Also, a considerable carbon build-up, mainly in the second ring groove, was observed. This paper presents the application of piston rings numerical simulation to predict the piston ring pack behavior and evaluate potential sources of OC which may explain the excessive values obtained in engine tests.

Nowadays, due to the high competitiveness in the automotive market, the car manufacturers and the engine developers are concentrating as many efforts as possible in order to diminish the lead-time to production and to promote cost reductions of their engine developments. As a consequence, many systems and component tests are being substituted by numerical simulations, allowing a significant reduction in the amount of engine and bench tests. The integration of individual numerical simulation tools generates the philosophy of Virtual Engine Development, which is based on the concept of simulating as much as possible the entire engine as well as its components behaviors. This paper presents the application of Virtual Engine Development (VED) in a PSA 1.4l SI engine development. Theoretical results of engine performance as well as powercell components behavior such as piston, rings, conrod, bearings, liner, engine block and cylinder head, among others, are presented and discussed.

The first proposal for an engine component usually is based on the supplier technical expertise, previous cases and/or selection manuals. Occasionally, this first proposal is also validated by numerical simulation; however, the main purpose is to satisfy a desirable target, not to assure an optimized nor robust proposal. The objective of the developed work is to present a proposed sequence for selection of one or as many as possible optimized and feasible proposals as well as the expected robustness in terms of performance for each proposal. This selection sequence is based massively on numerical simulation and on the advantageous expertise about the product. The example presented in this work is a ring dynamics simulation using an optimization method to select solutions that simultaneously reduce the blow-by and lube oil consumption (LOC). It is also presented the robustness calculation of the selected proposals.

It is well known the effect of localized loading on the bearing edges and thin oil film thickness on such regions due to high mechanical loads generated by combustion in conjunction with stiffness of the mechanical parts surrounding the bearing, i.e. engine block or connecting rod and shaft. The developed work takes in consideration the elastohydrodynamic behavior of a connecting rod bearing with pronounced loading leading to low oil film thickness on the bearing edges. Numerical simulation showed reduction of localized loading on bearing edges by introducing axial profiling. The numerical results were confirmed on actual engine test as well as on bench tests. The later showed 10% increase of load carrying capacity (LCC) for a regular bimetallic aluminum bearing. This study can lead to optimized bearing design to improve its performance by minimizing the contact pressure on the bearing edges and consequently increase significantly its LCC.

Due to recent advancements of computational resources, engineers have been focusing not only in the solution of single or repetitive complex CAE analyses, but also in the development of a CAE optimization environment, which is capable to drive design parameters towards regions where selected characteristics of the project can be further improved. In the present work two cases are presented in order to illustrate, respectively, the application of a Multi-Objective optimization algorithm and a Robust Design Optimization technique in the design of real engine components. In the first example a Multi-Objective Genetic Algorithm is used in the optimization of a Conrod-Bearing, aiming to minimize its mass without endangering its performance when peak torque conditions are applied.

Some of the current engine design requirements are the reduction of the engine weight and size and the power increasing. The components, like the connecting rod, should be re-designed in order to attend the trends. Other important variables are the increase of the engine speed and the peak cylinder pressure, higher the engine speed and peak cylinder pressure, higher the inertia and the gas pressure loads, respectively [2]. The combination of the trends mentioned before directly affects the con-rod bearing performance. In most cases, the optimization of the bearing profile can generate a significant improvement on the bearing performance. The use of the EHL numerical simulation is a powerful tool to design bearings and evaluate their performance. This paper presents, based on the EHL theory, a numerical evaluation of the performance of different connecting rod bearing profiles, both in circumferential and axial bearing directions.

The current SI engine designs submit the engine to operating conditions that require an improved performance of its components. The increase of the engine speed is a trend that generates a significant change in the engine components design approach. During validation tests, some engines have presented blow-by spikes at high speed and low load operating conditions. The reason is an abnormal ring package motion due to the influence of the high inertia and small gas pressure loads. This work presents a numerical simulation of a SI engine considering high speed and no load operating conditions, which showed blow-by spikes during engine tests. The numerical simulation tends to reproduce the blow-by spikes and identify the involved phenomena. Based on the numerical simulation, other engines were analyzed and some guidelines for the piston and the piston rings were developed in order to minimize the blow-by spikes at the mentioned operating condition.

One of the main trends in engine technology is the increasing of the engine power and peak cylinder pressure and the reduction of the masses of the engine components. The increased demands for higher engine performance with low friction losses require crankshaft and connecting rod bearings to operate under more severe conditions like higher speed, loads and temperatures. For many years, the classical hydrodynamic lubrication theory has been used to analyze the performance of the bearings. In this theory, the bearing housing is considered completely rigid. However, due to the engine trends, the bearing manufacturers have recognized the importance of considering the housing elasticity to improve the accuracy of the bearing performance analysis. This paper presents the results of the application of one of the developed models considering elasto-hydrodynamic lubrication simulation (EHL) of a connecting rod bearing used in a diesel engine.

Internal combustion engines normally use a pair of flanged bearing whose purpose is to carry axial loads resulting from the clutch system action and/or crankshaft impacts which unavoidably occur under real running conditions. There are alternative solutions to flanged bearings like, for example, thrust washers positioned directly onto the engine block but structurally decoupled from the respective main bearing. An engine designer's choice on the subject depends, in many cases, of his knowledge of similar engines with a reliable track record or of his personal preference for a specific solution that he is fond of However, the trend towards smaller and compact power units, i.e. of high power density (kW/L kW/cm2) has, as a result raised the mechanical loading imposed upon thrust bearings, in a number of cases, the thrust loads foreseen at the conception of the original design were exceeded by far. This factor alone results in excessive wear of the thrust faces.

For the development of engine components like pistons and rings, several numerical tools are employed of their performance evaluation in order to reduce the number of costly engine tests and samples required. An important limitation of the currently available codes that simulate piston ring dynamics is that they can be only used to study steady state engine conditions not allowing for the analysis of transient loads, for instance. This paper describes a proposed methodology for the simulation of transient loads yet employing existing codes. The method is used to study a real case of a diesel engine that showed excessively high blow-by fluctuations during its conventional running in cycle, more specifically at the load change from idle speed to peak torque. All assumptions and methodology are fully described, and predicted results for solution proposals are compared to engine tests in order to validate the procedure.

Erosion damage in engine bearings is becoming a major issue in premature bearing failure. Its occurrence is very difficult to predict at the design stage. This paper presents a simple mathematical technique based on an Eulerian approach that can predict some types of cavitation prone regions on a bearing surface.

Several cases of rod bearing shells assembled in highly loaded engines have been reported to show premature wear of the sliding surface, more specifically the electroplated lead-tin overlay. To understand these phenomena and overcome such occurrences, an analytical method has been developed to simulate the operation of specially designed journal bearings featuring circumferential profiling of the sliding surface. The resulting computer program solves the Reynolds equation taking into account a non-circular bearing surface, thus allowing for a customized design which extends operational component life through minimum oil film thickness (MOFT) increase and peak oil film pressure (POFP) and bearing back temperature (BBT) reduction. Theoretical results show an effective way to prevent premature wear.