Connecting Rod Bearings Research Articles

The patterns of changes in the degree of lubrication of the crankshaft bearings of car engines depending on the parameters of the load-speed modes of operation

The practice of operating machines and mechanisms indicates that bearing wear is one of the main reasons for limiting their durability. This especially applies to the sliding bearings of crankshafts of car engines, where the intensity of wear of their working surfaces significantly depends on the properties of the lubricant. An experimental study of the wear resistance of the sliding bearings of the crankshafts of car engines was carried out on the KI-5543 model break-in and braking stand. In experimental studies, BELZONA Super E-Metal insulating material was used to provide electrical isolation of the main and connecting rod bearings of the crankshaft from the cylinder block of the car engine. The experimental dependencies of the values of the criteria characterizing the degree of lubrication of the friction surfaces on the parameters of the load-speed modes (the moment of the applied force and the frequency of rotation of the crankshaft) were obtained. The ranges of values of the investigated parameters, in which the effective operation of the sliding bearings of the crankshaft of car engines is implemented, have been revealed.

Метод исследования формоизменения шатунных вкладышей коленчатого вала автомобильного двигателя в эксплуатации (на примере КамАЗ-740)

The relevance of the topic of the article is due to the unresolved problem of failures of automobile engines, in particular, modern mass-produced engines of the KAMAZ-740.10, 7403 families, due to cranking of the connecting rod bearings, and the need for deeper studies of the processes and phenomena that lead to them, and the development of solutions that exclude them in operation. The purpose of the study is to ensure the reliability of automobile engines by reducing the risk of crankshaft connecting rod bearings turning in operation by developing a method for studying their shape change and applying it when substantiating and implementing various design, technological and operational solutions. A prototype is described and a developed method and device for determining the clearance in a connecting rod bearing, suitable for studying the formation of connecting rod bearings under engine test bench conditions. The prototype was a differential-type pneumatic device used in active control devices for honing cylinder liners. With the use of the described device, a method for studying the formation of connecting rod bearings under the conditions of bench tests of KAMAZ-740.10 diesel engines was developed and tested. The use of new methods, devices and techniques makes it possible to investigate the patterns of shape changes of connecting rod bearings in relation to lubrication conditions, temperature and load conditions of the engine, and other factors. The presented experimental results show that the gap in the connecting rod bearing is not stable, is caused not only by wear, but also by the resulting deflection of the liner, and significantly depends on the temperature regime of the engine - with an increase in oil temperature, the gap decreases due to an increase in deflection. The authors explain the formation of deflection and shape change of the liners by the loss of its stability from the action of loads and internal stresses under conditions of instability of the oil supply. The results of experimental studies presented in the article have a scientific novelty, since a previously undescribed and not fixed decrease in the gap due to the deflection of the liners, which is formed immediately from the start of operation after the engine is assembled, is established, and its value is variable and determined by the temperature regime. Practical significance – the developed method makes it possible to study the formation patterns of crankshaft connecting rod bearings to test the effectiveness of design, technological and operational solutions to prevent their turning during the operation of an automobile engine. The main directions of promising research is the substantiation of practical solutions to ensure the stability of the shape of the liners during long-term operation of the engine.

Improvement of tribological properties of bearings by laser processing of cast-iron shafts of heavy-duty diesel engines

The article discusses the tribological properties of plain bearing materials in heavy-duty diesel engines with a cast-iron crankshaft. The effectiveness of the influence of laser hardening of shaft necks on the tribological properties of main and connecting rod bearings in comparison with nitriding is substantiated. Simulation comparative tribological tests have been carried out on a laboratory friction machine on samples of materials of an insert made of bronze Br-30 and a shaft made of high-strength cast iron with nodular graphite under conditions of sliding friction with lubrication after laser treatment hardening and nitriding. The influence of hardening treatments of the shaft necks on the antifriction properties and wear resistance of friction couples materials is investigated. Particular attention is paid to the scuff resistance of friction couples. The assumption of a higher efficiency of laser hardening in comparison with nitriding based on the tribological properties of friction surfaces is substantiated. Based on the study, it is recommended to use laser hardening of the crankshaft necks to increase the service life of heavy-duty low-speed diesel engines.

АНАЛИЗ КИНЕМАТИЧЕСКОЙ СХЕМЫ ПОРШНЕВОГО W-ОБРАЗНОГО ДВИГАТЕЛЯ С ПРИЦЕПНЫМИ ШАТУНАМИ

This article presents the analysis and results of analytical, calculation, and design solutions for the development of piston engines for aircraft (tractors, automobiles, etc.). The authors propose an original design of a W-shaped engine with trailer connecting rods and made a comparative analysis of design features. The main feature of the W-shaped engine design is a significant reduction in length, and, consequently, the length of the crankshaft. As known, the manufacturing of internal combustion engine crankshafts is a long, complex, and expensive procedure requiring a number operations for its mechanical and heat treatment. An important aspect of crankshaft design is the calculation of mechanical tension, torsional vibrations, and the hydraulic performance evaluation of the main and connecting rod bearing, including engine balancing as a whole. At the end of the article the operating schemes of the engine section are presented (the section consists of four pistons, two main and two connecting rods bearing kinematically connected to one crankpin). The design differences from the classical schemes of crank-connecting mechanism (CCM) allow us to design the W-shaped engine in accordance with the technical requirements. For example, maximum power can be achieved by using variant “A”, with an increase in the power and heat stress of the parts of the cylinder-piston group (CPG), when the section is organized according to variants “B” or “C”, the loading of CCM parts is increased, but the loading of CPG parts is reduced. Considering that a W-shaped engine with trailed connecting rods has a same piston stroke in main and side cylinders and the workflow pattern in each cylinder is identical and is moved at the crankshaft rotation angle – which allows the engine to be designed according to variants above – the performance characteristics of such an engine are significantly expanded due to electronic control. The authors consider continuation of the work in the implementation of a full set of calculation studies taking into account the design features of the engine with a W-shaped design of CCM.

Investigation of the Convergence of a Multi-Grid Algorithm for Solving the Task of Pressure in the Thin Lubricating Film of the Non-Newtonian Fluid

The article describes a multi-grid algorithm for integrating the Reynolds equation for hydrodynamic pressures in the lubricating film of a heavy-loaded journal bearing. This equation is the basic one in solving the tasks of designing friction units of piston- and rotary machines. Lubrication sources of various configurations in the form of grooves and holes located on the friction surfaces were taken into account. The version of the multi-grid algorithm developed by the authors is based on Brandt’s work. At each level of grids, not only the convergence of the solution is controlled, but also the rate of convergence. The pressure equation was approximated by finite differences using the control volume method and passed to a system of algebraic equations, which were solved by the Seidel method. Bessel formulas were used as the interpolation operator. The function for taking into account the non-Newtonian properties of the lubricant is based on the power law. Comparison of the developed algorithm with other versions showed high efficiency. The use of multi-grid algorithms makes it possible to perform multi-variant calculations of the dynamics of heavily loaded bearings. As a result of the calculations, the characteristics of the connecting rod bearing of the heat engine, as well as the multilayer bearing of the turbocharger, are presented.

Measurement of Piston Pin-Bore Oil Film Pressure under Engine Operation

Thin-film sensors were used to measure the oil film pressure distribution at the piston pin-bore interface in order to ascertain the stress distribution on the piston pin of a gasoline engine during actual operation. Thin-film sensors have been manufactured by a sputtering method to a total film thickness of about 3–6 μm. The features of thin-film sensors have been utilized to successfully measure the oil film pressure on engine main bearings, connecting rod bearings and piston skirts of both diesel and gasoline automotive engines. However, as engine lubrication conditions have become more severe year by year, it has become necessary to develop thin-film pressure sensors with higher durability. The use of diamond-like carbon (DLC) coating for the protective film of the thin-film sensor has enabled accurate measurement of oil film pressure under engine operating conditions. The AVL EXCITETM Power Unit was used in simulations with the application of elastic fluid lubrication theory. The calculated values were compared with measured data, and a comparison was made of the effect of the model constraint condition.

Experimental Measurements of Oil Films in a Dynamically Loaded Journal Bearing

This article describes the design of a journal bearing test platform capable of high-accuracy film thickness measurements via ultrasonic transducers permanently embedded in both the bearing and rotating shaft. A bespoke hydraulic loading system with programmable valves allowed the application of dynamic loads with defined loading patterns, including the simulation of loading patterns found in real components such as automotive connecting rod bearings. Tests under a range of rotation speeds, temperatures, and loading profiles allowed the detailed analysis of film thickness response to rapidly changing loads. Unlike conventional methods, the ultrasonic technique offers a noninvasive direct measurement of the shaft–bearing interface, thus enabling the study of phenomena such as squeeze film effects. Measurements were achieved by applying a novel referencing method, referred to as the “snapshot technique”. Via this method, squeeze time was shown to reduce with increasing shaft rotation speed, applied load, and bearing temperature. Results were compared against inductive sensors and numerical techniques and good agreement was observed.

Расчетно-экспериментальная методика определения предотказного состояния сложнонагруженных подшипников скольжения

The article deals with the types of wear and failures of journal bearings. Based on the physics of failures, a method for determining the pre-failure state of plain bearings is proposed, including: determination of the limiting clearance in the bearing; determination of the limit value of oil viscosity; determination of the limiting value of the ovality of the shaft neck and liners; determination of the maximum area of chipping of the surface of the liners; determination of the limit value of the concentration of active abrasive particles in the lubricant. The solution of these problems is based on the calculation of the determination of the hydromechanical characteristics (HMC) of bearings using the hydrodynamic theory of lubrication, the determination of the zones of contact interaction between the elements of the rolling stock, the duration of the boundary lubrication regime, the amount of wear on the surfaces of the sleeve and the shaft neck. Calculation studies were carried out on the example of calculating the dynamics of the connecting rod bearing of the crankshaft of a heat engine. In particular, it is shown that with a diametrical clearance in the connecting rod bearing of 90–120 μm, the duration of the boundary regime of lubrication is more than 25%, which is the limiting value. Reducing the oil viscosity (measured at 100 С) below 9.5 mPa∙s is unacceptable, as it leads to an increase in the duration of the boundary lubrication regime by up to 42%. For the same reasons, the ellipticity of the liners more than 5 microns is unacceptable. A mass concentration of active abrasive particles in the oil of more than 0.1% leads to a sharp increase in the maximum wear rate of the bearing, and this concentration should be considered the limit in terms of its pre-failure state. The technique allows at the early stages of designing machines, which include hydrodynamic plain bearings, to determine the criteria for their pre-failure state.

Оценка потерь на трение в текстурированных гидродинамических трибосопряжениях поршевых машин. Часть 2. Параметрические исследования шатунного подшипника ДВС

One of the ways to reduce frictional losses is to use texturing of the friction surface. The use of texturing affects the formation of cavitation and turbulence zones, which is a poorly studied aspect in the modern literature. The texturing of the crankshaft liners can be in the form of elliptical microwells of various sizes. The previous part was devoted to the description of the methodology for modeling the hydrodynamic losses in the lubricating layer taking into account the phenomena of cavitation and turbulence and the analysis of scientific sources. The parameter of the dimensionless distance to the wall y+ is considered in detail, as well as its influence on the calculation of the values of shear stresses using modern numerical methods. This paper presents the results of modeling the lubricant layer in connecting rod bearings with different types of liner surface texturing, at different loads. The initial data for modeling are based on experimental results. The calculations were carried out in the commercial software package ANSYS Fluent and software developed by the authors. The data obtained indicate a positive effect of the texturing of the connecting rod bearing friction surface on its hydromechanical characteristics with the correct selection of the texture geometric parameters, which in turn requires optimization and parametric studies. The values of the saturated vapor fraction depend on both the load value and the type of texturing. The purpose of this article is to assess the effect of texturing on the hydromechanical characteristics of a connecting rod bearing.

Influence of operating conditions on changes in wear parameters of ICE mating

Regularities of wear of mating of internal combustion engines operated in different conditions are discussed and analyzed. Regularities of wear of part mating in the process of technical operation of a motor vehicle are obtained. The correlation coefficients and the correspondence of the obtained regularities of wear to the experimental data have been determined. According to the research results, it was determined that during intercity transportation compared to transportation in settlements, the wear rate was lower by 47.7 % for cylinder liners, by 45.8 % for piston rings, by 40.12 % for connecting rod bearings and by 39.2 % for crankshaft necks. The research results can be applied when calculating connection resources in assembly units of machines.

Revisiting Mobility-Based Predictions of Cyclic Minimum Film Thickness in Big-End Connecting Rod Bearings

Revisiting Mobility-Based Predictions of Cyclic Minimum Film Thickness in Big-End Connecting Rod Bearings

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

The potential benefit of cylinder deactivation (CDA) on power and emission performances has been numerically investigated on a locomotive 16-cylinder diesel engine. A 1D model combined with a predictive friction model and a 3D combustion model based and validated on experimental data have been developed to simulate engine working processes by deactivating half of the cylinders by cutting off the fuel supply and maintaining/cutting off valve motions. The results demonstrate that CDA with the valves closed decreases the BSFC by 11% at 450 rpm and by 14% at 556 rpm with a load of 1000 N∙m, due to increased indicated efficiency and reduced mechanical losses. After deactivating cylinders, frictional losses of piston rings increase in the active cylinders because of the raised gas pressure and the lubricating oil temperature decrease. Friction losses of the main bearings and big-end connecting rod bearings decrease due to the overall load drop. In comparison with the normal operation, CDA with the valves closed decreases the BSCO emission by 75.26% and the BSsoot emission by 62.9%. As the EGR rate is 30%, CDA with the valves closed effectively reduces the BSNOx emission to 4.2 g/(kW·h) at the cost of a 0.8% increase in the BSFC and without the rise in the BSCO emission.

A transient and time lag deformation alternating-coupling micro elastohydrodynamic lubrication model

As transient and time lag deformations occur alternately and influence each other for viscoelastic materials of dynamically loaded journal bearings, the time lag deformation per unit time is defined based on the finite element stiffness equation and the standard linear solid model, accumulating it by loop and superposing transient deformation to obtain actual deformation at every moment. Thereby, a novel temporal association deformation equation of bearing is constructed. It is used to improve the film thickness calculation method of the traditional micro elastohydrodynamic lubrication (MEHD) model. Finally, a novel transient and time lag deformation alternating-coupling micro elastohydrodynamic lubrication (TTL-MEHD) model is established. The comparison between lubrication performance parameters calculated by the new model and the MEHD model under the eccentric motion of the journal proves the new model is correct, and can effectively analyze the knocking and rough rubbing characteristics at the early stage of bearing instability. The new model is implemented to explore the effect of the time lag degree of material deformation on mixed lubrication performance. The application of the new model in connecting rod bearing of internal-combustion engine proves that it can effectively compensate for the impact lag deviation caused by the complete elasticity assumption.

Вплив відцентрових сил на змащування підшипників колінчастого вала в аварійних режимах роботи двигуна автомобіля

The analysis of the crankshaft bearing condition of the automotive internal combustion engines in the case of insufficiency and breakage of oil supply to them is carried out. It is noted that this fault is one of the most common causes of damage to rubbing pairs in operation. At the same time, the different groups of bearings are often damaged, which cannot be explained within the framework of existing models of plain bearing lubrication. The objective of the work is to develop a mathematical model of oil supply to connecting rod bearings in emergency mode, taking into account the characteristic features of the bearing design. The model also, depending on the nature of the damage, should help to determine and explain the causes of bearing failures if they occur in different modes when operating conditions are broken. A computational model has been developed that makes it possible to assess the effect of design differences in the features of oil supply and the action of the centrifugal forces during crankshaft rotation on the oil column in the lubrication hole where oil is supplied to the conrod bearing. Calculations of the change in time of the oil supply pressure to the connecting rod bearings for the various designs of the crankshaft lubrication holes have been performed. It is shown that, depending on the operating mode of the engine and its design, the oil pressure in front of the connecting rod bearings does not disappear immediately after oil supply failure to crankshaft. Moreover, the lower the crankshaft speed is, the longer the lubrication of the conrod bearings will continue. The calculation results are confirmed by the data of the expert studies of the engine technical condition, in which the crankshaft was wedged in the damaged main bearings was found in the absence of serious damage to the connecting rod ones. It has been found that such features of the damage correspond to an rapid breakage of the oil supply to the crankshaft in the case of such operational damage as the oil pump and pressure reducing valve failure, the oil filter seal and oil pan destruction, etc. The developed model explains the difference in lubrication conditions and in the damage feature to the main and connecting rod bearings in the emergency cases of the oil supply breakage, which are observed during operation, and helps to clarify the failure causes. This makes it possible to use the model and the obtained data when providing auto technical expert studies of the failure causes of automobile internal combustion engines This makes it possible to use the model and the obtained data when providing auto technical expert studies of the failure causes of automobile internal combustion engines when the operating conditions are broken.

МЕТОДИКА ОЦЕНКИ ЭФФЕКТИВНОСТИ СРЕДСТВ ТЮНИНГА СМАЗОЧНОЙ СИСТЕМЫ АВТОТРАКТОРНЫХ ДИЗЕЛЕЙ

The work carried out a comparative analysis of various means of functional tuning of the lubrication system of automotive diesel engines of the KAMAZ family, such as: A device for monitoring the continuity of the oil flow to the connecting rod bearings during operation, an electronic indicator of oil consumption through the crankshaft bearings, an oil pumping system that allows pumping oil before starting a diesel engine in cold time, Hydroaccumulator allowing to pump oil through the turbocharger when the engine is stopped, Level regulator automatically maintains the optimum oil level in the crankcase, Limiting machine automatically stops the operation of the diesel engine. Ensuring an increase in the reliability and durability of automotive diesel engines. A brief description is given and an economic comparison of these tuning means is made. The values of the unit costs are given, taking into account the growth of the engine resource for each tuning option. The unit costs differ insignificantly. Preference can be given to the oil level regulator and the limit switch. In terms of economic indicators, the limiting machine of the lubrication system can be recommended for practical use, among other options for the functional tuning of cars.

Research on the Effect of Refrigerant Solubility on the Lubrication Characteristics of Connecting Rod Bearings

Research on the Effect of Refrigerant Solubility on the Lubrication Characteristics of Connecting Rod Bearings

Weak feature extraction for early wear of connecting rod bearings under transient conditions

As we all know, it is difficult to extract weak feature for early wear of connecting rod bearings under transient conditions. In order to solve the problem, a method of extracting wear features for connecting rod bearings based on variational modal decomposition (VMD) adaptive noise reduction and computational order tracking (COT) was proposed. Firstly, the vibration signals of internal combustion engine block under transient operating conditions were collected, and the signals were reordered to satisfy the order tracking condition. Then, interpolation and fitting techniques were used to map the signal from the time domain space to the angular domain space. Next, the VMD was used to decompose the angular domain signal into multiple modal components, and the autocorrelation function (ACF) was used to denoise the modal components adaptively. Finally, the signal was reconstructed to conduct COT analysis, and the wear features of connecting rod bearing were extracted by average COT spectrum. The simulation analysis and the simulation experiment of the connecting rod bearing fault show that the proposed method is effective, and the weak features for early wear of connecting rod bearing of internal combustion engine are extracted.

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.

Lubrication performance analysis of the connecting rod bearing based on AVL EXCITE

The lubrication state of connecting rod bearing has influence on the reliability and lifetime. It is necessary to analyze the lubrication state of connecting rod bearing to evaluate and design the lubrication performance. The connecting rod bearing hydrodynamic lubrication simulation model was set up for 9XX diesel engine and journal bearing fatigue test-rig at Glacier Vandervall. The effect of maximum oil film pressure, minimum oil film thickness and maximum asperity contact pressure on the lubrication performance were studied. Then the lubrication states of connecting rod bearings under different working conditions were discussed based on two test machines. The results are of great significance for analyzing the lubrication performance of connecting rod bearings and the reliability of bearings.

Study of the Piston Secondary Movement on the Tribological Performance of a Single Cylinder Low-Displacement Diesel Engine

The present study aims to analyze the secondary movement of the piston considering the deformations present in the piston skirt, the hydrodynamic lubrication, and the effects of the clearances in the connecting rod bearings. The analysis of the piston movement is performed by developing a mathematical model, which was used to evaluate the dynamic characteristics of the piston movement, the slap force on the piston skirt, the effect of the secondary piston movement on the connecting rod, and the influence of clearances in the connecting rod bearings and in the piston. For the study, the geometric of the crankshaft-connecting rod–piston system of a single-cylinder diesel engine is taken as a reference. The deformation model of the piston was carried out by means of a symmetric finite element model (FEM), which was integrated into the mathematical model of the piston. MATLAB® software (The MathWorks Inc., Natick, MA, USA) is used for the development of model simulations. The obtained results show that during the combustion cycle, there are six changes of direction in the secondary movement of the piston with lateral and angular velocities that can reach a magnitude of 0.13 m/s and 4 rad/s. The lateral and angular movement of the piston during its travel causes the appearance of impacts on the piston skirt with the cylinder liner, which produces an increase of approximately 500 N in the hydrodynamic forces in the connecting rod bearings. The force analysis shows that the range of the maximum magnitudes of these forces is between 1900 N and 3480 N. The increase in clearance between the cylinder liner and the piston skirt (Cpc) causes a greater lateral displacement and an increase in the angle of inclination of the piston. Analysis of the change in connecting rod bearing clearance shows that there are critical values in relation to clearance Cpc. The model presented allows us to analyze the different characteristics of the secondary movement of the piston, which involve the interaction between the piston skirt and the cylinder liner. Additionally, the influence of this movement on the connecting rod bearings is considered. The foregoing can be used as an analysis tool for the study of designs and/or modifications in the engine in such a way that greater durability of the components, reductions in acoustic emissions, and reduction in friction losses are achieved.