Connecting Rod Big End Bearings Research Articles

Effects of Hyperelliptic Bearings Bush on Connecting Rod Big-End Lubrication and Design Optimization

Aiming at the impact of bearing bushes on the lubrication and friction and wear of diesel engine connecting rod big-end bearings, a certain type of diesel engine connecting rod big-end bearing bush was taken as the research object and a multi-body dynamics numerical calculation model of the connecting rod group was built. The connecting rod big-end bearing bushes with four profiles: exponential, hyperelliptic, barrel and trapezoid were used to study the effect on bearing lubrication. The study found that the hyperelliptic bush has the best lubrication performance for the connecting rod big-end bearing. On the basis of the hyperelliptic bush, the bearing clearance, bearing width, journal oil hole diameter and oil supply pressure are used as design variables, using the Box–Behnken experimental design and radial basis function (RBF) neural network method to construct an approximate multi-objective model, which the minimum oil film thickness (abbreviated as MOFT) and average rough contact effective pressure are the objectives. A non-dominated sorting genetic algorithm (NSGA-II) is used for multi-objective optimization. The optimization results show that the bearing clearance remains basically unchanged, the bearing width, journal oil hole diameter and oil supply pressure increase, so that MOFT of the connecting rod big-end bearing rises from 1.56 μm to 1.97 μm, and the average rough contact effective pressure increases from 3.97 MPa decreases to 0.25 MPa. The research results can provide a reference for the analysis and optimization of the lubrication performance of the connecting rod big-end bearing.

A Visualization Solution of the Stress State of Connecting-rod Big End in the Experimental Device for Lubricating Condition of the Connecting-rod Big End Bearing

This paper presents a visualization solution of the stress state of the connecting-rod big end in the experimental device for lubricating of the connecting-rod big end bearing. The connecting-rod model is in photoelastic material that is subjected to the load simulation corresponding to the engine's operating cycle. This experimental device and the connecting-rod model are used to determine the load diagram, measure the oil film pressure, oil film thickness, oil film temperature. In this study, a visualization system of stress state in the connecting-rod big end is built that stress of connecting-rod is one of the characteristics when we study the connecting-rod big end bearing. The stress state of the connecting-rod is visualized by the transmission photoelasticimetry. This method allows the visualization of the isochrones fringes, which are lines of equal difference regarding the main stress in the connecting-rod. The visualization system consists of a polarizer, two quarter ware blades, and an analyzer. The stress contour’s images of the connecting-rod at different angles of the crankshaft are realized by a CCD camera. The stress state in the connecting-rod is compatible with the load applied.

Thermo-Hydrodynamic (THD) Analysis of Oil Film Lubrication in the Connecting-Rod Big End Bearing

Thermo-Hydrodynamic (THD) Analysis of Oil Film Lubrication in the Connecting-Rod Big End Bearing

Wear study and EHD lubrication analysis on connecting rod big end bearings of off‐highway application engine

AbstractThe connecting rod big end bearings are under dynamic lubrication during working cycle, and in most of the time, the con rod is subjected to compressive stress. The conventional method of performing an EHL analysis on a bearing involves development of complex mathematical equations and simplification of actual physical model. This paper presents a methodology to model and simulate the elastohydrodynamic lubrication and wear study of connecting rod big end bearings of off‐highway application engine using the application of computational fluid dynamics (CFD) and computational structural dynamics (CSD) approaches. The pressure field for a full journal bearing operating under laminar flow regime with various eccentricities was obtained by CFD, and fluid pressure distribution and deformation in the bearing liner due to pressure were evaluated using FSI approach. Relevant parameters of lubrication characteristics were analyzed to optimize the eccentricity value. The maximum bearing load value of 21 kN was noticed at TDC position for the optimum eccentricity. The load distribution indicated critical points in the bearing, and the data obtained from bearing load and sliding velocity of journal were used in Archard's wear relation to determine the wear depth along the bearing width. The simulated wear results were compared with three‐cylinder off‐highway application engine con rod big end bearings, which ran for 1000 hours at full load condition, and satisfactory agreement was observed between experiment and simulation values.

Numerical Study of Power Loss and Lubrication of Connecting Rod Big-End

A hydrodynamic lubrication analysis for connecting rod big-end bearing is conducted. The effects of engine speed, operating condition, lubricant viscosity and oil temperature on tribological performance of big-end bearing have been examined. Force equilibrium is solved to define instantaneous eccentricity between journal and bearing to have accurate estimation of oil film thickness at interface of connecting rod big-end bearing and crankpin. Connecting rod big-end is treated as π film hydrodynamic journal bearing and finite difference scheme is applied to calculate generated hydrodynamic pressure and frictional power loss at each crank angle. Beside the development of analytical formulation, well-known Mobility model introduced by Booker has been employed to be compared with the analytical model. The presented analytical model reduces the complexity and the numerical effort with respect to Mobility method, thus shortening the computation time. The simulation results show good agreement between analytical model, Mobility approach and experimental data.

Partitioned fluid-structure interaction techniques applied to the mixed-elastohydrodynamic solution of dynamically loaded connecting-rod big-end bearings

Abstract The present contribution proposes different partitioned techniques, which are commonly used in fluid-structure interaction (FSI) applications, in the context of tribological simulations of the transient mixed-elastohydrodynamic problem of dynamically loaded connecting-rod bearings. With the premise that the FSI framework developed is general, in the current work the fluid flow effects have been considered through the averaged Reynolds equation by Patir & Cheng and the mass-conserving p − θ Elrod-Adams cavitation model. The multiphysics simulation framework developed has been used to simulate the connecting-rod big-end bearings of both heavy-duty diesel and high-speed motorcycle engines. In the latter case, the influence of polymer concentration in VM-containing oils with similar HTHS150 values on the bearing power loss is investigated and discussed in details.

Partitioned fluid-structure methods applied to the solution of elastohydrodynamic conformal contacts

The functional characteristics of statically-loaded journal bearings operating in the elastohydrodynamic lubrication (EHL) regime are evaluated by means of three partitioned fluid-structure coupling methods. Widely used in other areas but yet unexplored in the context of EHL problems related to journal bearings, these methods permit the use of optimized codes to solve the hydrodynamic and structural equations separately employing different techniques specialized in each type of equation. In this study, lubricant pressures are calculated using the isothermal Reynolds equation and the p−θ mass-conserving formulation is adopted for the computation of cavitation effects. An appropriate substructuring technique is applied in order to reduce the order of the bearing 3D linear-elastic finite element model. The efficiency and robustness of the partitioned fluid-structure coupling methods presented are assessed for two extreme situations of high deformation and high load conditions of a typical internal combustion engine connecting-rod big-end bearing. Numerical results evidence that partitioned fluid-structure coupling methods consist in a very efficient simulation tool for EHL journal bearing analyses.

Stress Analysis on a Connecting Rod Big End Bearing of Two-Stroke Marine Diesel Engine

In this paper, the multi-body dynamics software EXCITE was used to simulate the connecting rod big end bearing of two-stroke marine diesel engine. The result showed the stress analysis of connecting rod big end bearing. The purpose is to provide a theoretical basis for the actual conditions of connecting rod big end bearing, and to improve the design of the crankshaft structure.

The Elastohydrodynamic Lubrication Analysis of Journal Bearing

Based on the flexibility matrix method, the elastohydrodynamic lubrication performance of journal bearing are studied. Comparisons are made the effect of elastic deformation on the center orbit of connecting rod big end bearing. The results show that bearing eccentricity has far exceeded 1 near the maximum combustion pressure, considering the elastic deformation of connecting rod big end bearing, changing trend of bearing center orbit is the same at other times.

Metamodel-Assisted Optimization of Connecting Rod Big-End Bearings

From a very general point of view, optimization involves numerous calculations and therefore a high computational cost. In the fields where a single calculation is long and the optimization is crucial, specific techniques, devoted to this task, have been developed. First, the surrogate-based models are introduced and a short review of optimization in tribology is presented. The aim of the present work is to combine both. To demonstrate the power of the methodology on a lubricated bearing, the theoretical background is first outlined. Then, the two aforementioned processes are described: the construction of the surrogate, based on the Finite Element Method well-chosen computations, and the Multiobjective Optimization, thanks to a Nondominated Sorting Genetic Algorithm. Both are utilized on a connecting rod big-end bearing. As a result, the power loss and the functioning severity are simultaneously minimized upon a set of ten input parameters. The user is then provided with simple analytical expressions of the input variables, for which the bearing behavior is optimal.

The Analysis of the Deformation and Contact Lubrication Problem of HPD Diesel Engine Connecting Rod Bearings Based on the FFT Method and Flexibility Matrix Method

Based on the fast fourier transform (FFT) and flexibility matrix method, the effects of the FFT and flexibility matrix method on the distribution of oil film pressure, elastic deformation in the steady load and the journal center orbit of the connecting rod big-end bearings in the dynamic load are investigated. The results are shown that when the eccentricity ratio is more than 1, the maximum oil film pressure obtained by FFT method is bigger on both ends of the journal bearing and on its intermediate position is smaller. To the connecting rod big-end bearing, under the dynamic load condition, there is the same trend of the journal center orbit with two methods. However, with FFT method, the journal is largely deviated from bearing center.

Using Design of Experiments to Analyze the Connecting Rod Big-End Bearing Behavior

Reducing the frictional loss in internal combustion engines (ICE) represents a challenge, in which all car manufacturers are involved. This concern has two origins. The first one is the fuel cost, which increases over the years. The second is strongly linked to ecology: people feel more and more concerned by the greenhouse effect, partly resulting from fuel consumption. Many projects involving several laboratories and lead by car manufacturers have this particular point as main subject, with the goal to reduce the ICE fuel consumption by decreasing the friction power loss. This aim can be partly achieved with a better knowledge of the connecting rod big-end bearing functioning. A lot of theoretical and experimental studies have been carried out, resulting in efficient models for numerical simulations, but at the time, no known ambitious parametric study has been planned, to determine the most influent parameters and to quantify their effects on power loss. The present work is a first step to bridge the gap between the potential of recent numerical simulations and the need for a better understanding of the connecting rod big-end bearing functioning. To plan the numerical simulations, it will be taken advantage of design of experiment techniques, which provide an efficient way of preparing the series of experiments with a minimum of runs. Thus, these techniques are illustrated through the variable combination run, test results generated, and interpretations made to identify the dominate factors impacting the responses of interest.

Engine Lubrication System Analysis by Considering Aeration and Cavitation within the Rotating Oil Supply Passage

The connecting rod big-end bearing is one of the most heavily loaded components of the lubrication circuit system of modern combustion engines. The bearing's oil supply has to be designed accordingly in order to ensure its sustainable operating reliability. As can be seen, the oil supply has to pass the main bearing and the rotating crankshaft before entering the connecting rod bearing. It is common knowledge that the centrifugal forces due to the crankshaft rotation affect the oil flow through the rotating supply passage into the rod bearing. The oil pump has to maintain a certain pressure level in the main oil gallery to overcome these centrifugal forces. In the early eighties, the second oil pressure limitation to the rod bearing operation was identified, which is lower than the centrifugal pressure limit. As a result of this, the dissolved air will be released in the rotating oil passage due to the pressure decrease caused by the centrifugal forces. Aeration or cavitation within the rotating oil supply passage occurs at much lower oil pressure. The detrimental effects of aeration or cavitation are loss of lubrication, overheating, metal erosion, mechanical shocking, and even system component failures. In this paper, a novel approach of identifying the second pressure limit is introduced by applying the CFD method. The three-dimensional, transient, multiphase flow in the transfer passage has been solved by considering its dynamic attributes. The characteristics of the aeration and cavitation flows and their effects on rod bearing oil supply have been investigated. The mechanisms underlying the interrupted oil supply to the rod bearing have been discussed in detail by studying the dynamics of aeration and cavitation. Finally, a map of the operational range has been established as an exemplary guideline for the design of engine lubrication systems and the key operating conditions including rotational speed and main bearing inlet pressure. Review led by Yuan-Ren Jeng

Analysis of diverse simulation models for combustion engine journal bearings and the influence of oil condition

The paper deals with the comparison of different models, from simple to complex, for the simulation of non-stationary response of the journal bearings used in combustion engines. The variety of simulation models covers classical methods from Holland, Butenschoen and numerical methods based on the Hydrodynamic (HD), Elasto-hydrodynamic (EHD) and Thermo-elasto-hydrodynamic (TEHD) lubrication theory. Several crankshaft main bearings and connecting rod big end bearings are investigated. The comparison includes the following bearing parameters: Peak Oil Film Pressure (POFP), Minimum Oil Film Thickness (MOFT) and oil flow. Calculation time is compared, too. Estimation of oil viscosity is discussed over a typical temperature and pressure range found in combustion engines, including the influence of the fuel dilution as an example of the oil aging phenomena.

Analysis of non-Newtonian and piezoviscous effects in dynamically loaded connecting-rod bearings

The dynamic behaviour of three elastic connecting-rod big-end bearings is studied. Non-Newtonian and piezoviscous behaviour of the lubricant is included. The present algorithm allows accurate analysis of film rupture and reformation during actual operation of an engine and is based on finite element discretization. The non-Newtonian effect is introduced by modifying the viscosity for each point of a three-dimensional mesh of the film and for each iteration. Using a convenient iterative solution procedure, converged solutions for lubricant flow and elastic deformation fields are obtained. The present algorithm is extended to a global thermo-elastohydrodynamic model, to take into account the effects of viscosity variation with temperature. It is shown that the non-Newtonian shear-thinning and oil piezoviscous effects cannot be neglected in a complete connecting-rod bearing analysis. Furthermore, thermo-elastic behaviour can lead to different conclusions, than obtained by the elastohydrodynamic model.

A Nonlinear Structure Based Elastohydrodynamic Analysis Method for Connecting Rod Big End Bearings of High Performance Engines

Big end bearings of connecting rods for high performance automotive engines are quite compliant and exhibit relatively large deformations at high rotation speed. Nowadays numerical simulation provides good estimate of tribological parameters for bearings operating in severe, but not extreme elastohydrodynamic lubrication conditions. At very high rotation speed regimes, reliable previsions are achieved only if an effort to increase the accuracy of structural modeling is accomplished. A finite element model able to account for the nonlinear friction controlled sliding phenomena occurring at the junction surface between the cap and the body of the rod has been developed. A new method to solve the coupled equations governing the interaction between the hydrodynamic fluid model and the nonlinear structural model of the connecting rod bearing is presented, together with a simple application example.

Thermoelastohydrodynamic lubrication for the connecting rod big-end bearing under dynamic loading

This paper discusses an experimental device used to investigate thermoelasto-hydrodynamic behaviour of connecting rod big-end bearing models. Theoretical results for this device are obtained by calculation with a two-dimensional thermoelastohydrodynamic model. A brief description of both theoretical development and experimental device is presented. After the presentation of measurement results, a comparison with theoretical results is discussed.

エンジン軸受の連成解析と簡略解析 : コンロッド大端部軸受とピストンピン軸受(エンジンのトライボロジー・潤滑油,エンジンのトライボロジー・潤滑油)

エンジン軸受の連成解析と簡略解析 : コンロッド大端部軸受とピストンピン軸受(エンジンのトライボロジー・潤滑油,エンジンのトライボロジー・潤滑油)

Vibration Analysis of Connecting Rod Big End Bearings

The aim of the work described in this paper was to compare 'finite bearing' and 'short bearing' models of connecting rod big end bearings with measured practical performance. The effects of bearing shell distortion were also to be investigated, and an assessment made of a novel approach to collecting experimental data from a running internal combustion engine. Theoretical results were obtained for models based both on a 'finite bearing' solution and on the 'short bearing' approximation. Results were calculated for both a circular bearing profile and also for a distorted bearing profile, such as might be caused by the interference 'nip' between the bearing shell and the connecting rod. Experimental data was collected from a single cylinder diesel engine. The results of the work show that a 'full' bearing analysis predicts smaller values of minimum oil film thickness than those obtained when the short bearing approximation is used, and that bearing shell distortion leads to smaller values of minimum oil film thickness. Values of minimum oil film thickness inferred from practical measurements were generally found to be larger than those predicted by theory however, probably because of further bearing shell deflection caused by the oil film forces. The experimental procedure investigated proved useful for measuring changes in oil film thickness, but less useful for measuring absolute oil film thickness.

Comparison between experimental film thickness measurements and elastohydrodynamic analysis in a connecting-rod bearing

This paper describes the experimental measurements and the theoretical calculations of oil-film thickness in a dynamically loaded connecting-rod big-end bearing. Four eddy current gap sensors for each bearing are used to measure the oil-film thickness and to deduce the bearing trajectories. Experimental data for crankshaft main bearings are easy to obtain but connecting-rod bearings are more difficult to control due to the difficulty of installing instrumentation on connecting-rods that are rotating and reciprocating. The solution uses a mechanical linkage fixed under the piston axis. The elastohydrodynamic model considers connecting-rod elastic deformations. The calculation process uses finite element and Newton-Raphson methods for the numerical analysis. Comparisons of both the load and crankshaft speed effects are made between experiment and the theory.