Piston Ring Cylinder Research Articles

Investigation of the Influence of Lubricating Oil Viscosity on the Wear-Reducing Characteristics of Cylinder Liner Surface Texture

Lubricating oil and cylinder liner surface textures can significantly reduce the friction coefficient between the piston ring and the cylinder liner, thereby improving engine performance. However, the friction-diminishing mechanisms between the lubricating oil and surface texture remain unclear. Properly combining lubricating oil and surface texture can achieve better friction reduction effects. This paper, based on a transient thermo-hydrodynamic model developed in MATLAB 2020a, conducted numerous simulation experiments to explore the matching characteristics of textured cylinder liners. The study provides theoretical support for the future selection of lubricating oils for textured cylinder liners. The results show that, within the range of the circular texture parameters used in this study, the texture radius is directly proportional to the reduction in friction mean effective pressure (FMEP), while the texture depth is inversely proportional to the FMEP reduction. At the same rotational speed, as the viscosity of the lubricating oil increases, the friction-reducing effect of the texture on the piston ring–cylinder liner pair decreases. When the texture depth is 2 μm, the engine speed is inversely proportional to the reduction in FMEP. As the texture depth increases from 2 μm to 6 μm, there is a significant change in the friction-reducing effect: for the 2 μm texture, the friction-reducing impact decreases with increasing lubricant viscosity, while for the 6 μm texture, the friction-reducing effect increases with increasing lubricant viscosity.

Simplified Wear Model for Power Cylinder under Engine Operating Conditions

A simple numerical approach is developed to predict the wear and friction of piston ring pack and cylinder liner during the break-in period and under transient speed conditions. In the model, a solution of mixed lubrications using the load-shearing concept is presented based on the selected elastic-plastic equations of asperity contacts in conjunction with well-established elastohydrodynamic equations. The model takes shear-thinning, thermal effects in elastohydrodynamic lubrication (EHL) and lubricant starvation effects into account. Modified Archard’s wear coefficient to describe the piston ring against cylinder liner wear is introduced. The approach is valid for the calculations of the asperity pressure at low values of the ratio of oil film thickness to combined roughness of the interacting surfaces, that is, less than 0.5. Applications are discussed, including association of piston side thrust force on wear and friction characteristics of piston ring/cylinder bore, gas blowby through the ring pack on the cylinder liner wear, a strong coating dependence for the piston ring wear, and wear distribution across the stroke under engine operating conditions. A good agreement between the experimental and analytical data indicates that the proposed model can be used to predict the wear and friction of the piston ring pack sliding against cylinder liner.

A Comprehensive Review on Tribological Behaviour of Hybrid Nanocellulose-CuO as Nanolubricant for Piston Ring Cylinder Liner Application

Friction coefficient and wear rate are crucial performance for the development of nanolubricants, which are of great significance for realizing energy conservation and prolonging service life of mechanical components. Herein, this review systematically describes the progress on nanocellulose (CNC) and Copper (II) oxide (CuO) as effective nanoparticles for developments of nanolubricant as oil additives for improving the anti-friction and wear resistant for piston ring-cylinder liner contact. Additionally, we point out several problems existing in the applications of CuO and CNC additives propose the possible solutions. Finally, the research prospects of CNC-CuO in the field of tribology are prospected.

Influence of Liner Surface with Parameterized Pit Texture on the Friction Characteristics of Piston Rings

The arrangement of a pit-shaped surface texture on the surface of a cylinder liner significantly affects reductions in piston ring friction, and the influence of the structural parameters and spatial distribution on piston ring friction power consumption is unclear. In this paper, the diameter, depth, axial spacing distance, and radial spacing distance of the pits on the inner surface of a cylinder liner were used as variable parameters to process the surface textures of different schemes, and then a friction and wear test was carried out on UMT piston ring–cylinder liner specimens, several texture schemes with the best anti-friction effect were selected, an engine bench test was carried out by comparing these texture schemes with non-texture schemes, and the frictional torque and fuel consumption of the engine were studied at different oil temperatures. The results show that the depth of the pits in the surface texture of a cylinder liner has a greater influence on the friction reduction effect, followed by the radius. The higher the oil temperature in the engine bench test, the greater the impact of the surface texture. The reduction in fuel consumption was greater in the lower-speed region after structuring the textured cylinder liner compared to the non-textured cylinder liner. Specifically, the friction coefficient was mainly affected by the depth of the pits, and the depths of the pits in the texture schemes with good friction reduction effect were all 17–19 μm. The best friction reduction could be achieved when the pit radius is around 50 μm, with little difference in pit depth. When the oil temperature was 95 °C, the average drag torque reduction was about 1.69 Nm; when the oil temperature was 105 °C, the decrease was about 2.54 Nm; and when the oil temperature was 105 °C, the decrease was about 4.53 Nm. After adding the surface texture of the cylinder liner, the fuel consumption rate of the engine equipped with the structured cylinder liner was generally reduced compared with that of the original cylinder liner engine. Among them, the average and subsequent consumption rate of surface assembly scheme 11 decreased the most, with a value of 1.3 g/kwh.

Low and high temperature effects on friction and wear performance of Cr-plated cylinder liner

Cr-plated cylinder liners with good wear and corrosion resistance as well as high strength are suitable for application in low-carbon fuel engines. A reciprocating friction and wear tester was used to measure the friction and wear performance of the Mo-sprayed piston ring and Cr-plated cylinder liner at low and high temperatures. For the low temperature conditions from −20 °C to 20 °C, the worn surface of tribo-pair was more prone to spalling. Once the load went up to 66 MPa under low temperatures, cylinder liner scuffing occurred. As the temperature increased from 90 °C to 240 °C, the honing textures of the Cr-plated cylinder liner presented gradually shallow with more abrasive marks along the sliding direction. The tribo-chemical reaction products of zinc dialkyldithiophosphates (ZDDP) with white bright spots distribution provided better protection of the tribo-pair to avoid severe fatigue spalling. The influence of temperature effects on the ZDDP decomposition and surface spalling damage should not be underestimated for Cr-plated cylinder liners.

Thermohydrodynamic Lubrication Characteristics of Piston Rings in Diesel Engine Considering Transient Heat Transfer under the Parameterized Surface Texture of Cylinder Liners

The cylinder liner and piston ring form the most crucial friction pair in the diesel engine, contributing 35–40% of its overall friction losses. Recent research indicates that transient heat transfer significantly affects piston ring lubrication. However, the impact of such a transfer on varying surface textures and lubrication traits remains unclear. This paper takes the piston ring–cylinder liner of a certain diesel engine as the research object, which is based on a two-dimensional averaged Reynolds function and Greenwood–Tripp micro convex body contact model; establishes a numerical calculation model of the transient heat fluid lubrication characteristics of a vertical piston ring–cylinder liner assembly by combining the oil film thickness equation, energy equation, lubricating oil viscosity–temperature, and viscosity pressure characteristics; avoids large errors associated with assuming different temperature values for lubricants; and also uses the cylinder liner surface texturing technique to examine the effects of surface texturing on lubrication properties in the presence of transient thermal fluids. The findings indicate that employing transient thermal fluid for determining the mean value of the oil film temperature in isothermal lubrication calculations yields comparable values for minimum oil film thickness and frictional power consumption, while the friction power consumption calculated by the transient thermal fluid is slightly lower. The depth of the recesses on the surface of the cylinder liner should be minimized, while the radius of the texture should be maximized, taking into consideration the current circumstances. Compared with a cylindrical texture, a spherical texture achieves lower friction with good lubrication indexes.

Fullerene Oil Tribology in Compression Piston Rings under Thermal Considerations

To enhance the efficiency of automotive engines, a comprehensive understanding of friction generation within their components is paramount. Moreover, extensive global research efforts have been dedicated to nanoparticles, leading to the emergence of nanolubricants. In this study, an investigation was conducted focused on the piston ring–cylinder tribological interaction using fullerenes as additives. This is a very important issue since the friction forces can be significantly reduced. In order to solve this problem, a 2D CFD approach was implemented, taking into account a roughness model and temperature variations. The obtained results clearly show a friction reduction using fullerenes as additives compared to both synthetic and monograde oils. Furthermore, using fullerene oils, the performance of the compression piston ring system is improved due to friction reduction and the change of the temperature distribution. This study is beyond SOTA, since there is a limited contribution in the field of such nanolubricants in compression piston ring system. It is evident that the friction force is reduced by 42% compared to synthetic oils, showing a perspective on more tribologically efficient internal combustion engines.

Analysis on Lubrication Performance of Piston Ring-Cylinder Liner based on Numerical Simulation

This paper mainly studies the tribological performance of friction pairs and poor lubrication during piston movement. Based on the average Reynolds equation and comprehensively considering the variable viscosity and variable density characteristics of lubricating oil, a transient hydrodynamic lubrication model of the piston ring-cylinder liner friction pair is established. By solving the established lubrication model, the lubricating oil film thickness value, friction value and other parameters that can characterize the lubrication performance of the friction pair throughout the cycle are obtained, whilst revealing the surface roughness, lubricating oil viscosity and piston ring barrel surface height. And the influence mechanism of the friction performance of the friction pair is presented on the basis of the previous analysis. The research shows that improving the surface roughness of the piston ring will help to improve the lubrication, increasing the viscosity of lubricating oil will help to improve the lubricating performance of friction pairs and reduce the peak friction at the top dead centre of piston rings and improving the surface texture of the piston rings can reduce the oil film thickness and reduce the friction caused by fluid shear effect in the high-speed region.

Simulation based analysis to study the effect of compression ring crown height in ring liner assembly on the performance of four stroke petrol engine

Among different piston rings of an Internal Combustion Engine (IC), the top compression ring-liner assembly shared a momentous amount of the total frictional losses, particularly at the Top Dead Center (TDC) and Bottom Dead Center (BDC) where boundary lubrication subsists. In the present study, the lubrication mechanism in piston ring cylinder liner conjunction for top compression ring using one dimensional Reynolds equation assuming axisymmetric contact was studied. The hydrodynamic and mixed lubrication regimes were taken during the study. Gumbel boundary conditions were used for Reynolds equation solution. For boundary pressure calculation, first, combustion chamber pressure variation was determined, then, interring pressure was calculated assuming orifice volume method by solving mass flow rate through crevice volumes using Runge-Kutta 4th order method. The Reynolds equation was solved using finite difference method. Whole solution process was repeated for different engine speed and crown height of top compression ring to study the effect of them in wear and power loss. First, the solution was found for 3000, 5000 and 7500 RPM keeping constant crown height of 10 µm. Average power loss was found to be increased with the increasing engine speed. There was increased in oil film thickness around mid-stroke with the increased engine speed, but there was no significant change in film thickness with the engine speed at the TDC and BDC positions. Then, the solution was again repeated for different RPM varying the crown height. The compression ring with lower crown height showed the better wear performance by increasing the minimum film thickness in critical zones of engine cycle for all RPM. The crown height of 5,7 and 9 µm gave the minimum power loss (77.89, 163.47 and 297.33 W) for 3000, 5000 and 7500 rpm. Moreover, the power loss in the range of 5-9 µm had no significant differences.

Coated Piston Ring Pack and Cylinder Liner Elastodynamics in Correlation to Piston Subsystem Elastohydrodynamic: Through FEA Modelling

A finite element model is developed to assess the effects of the TiSiCN thin film coating of the piston ring on the structural strength of the piston subsystem. The complex, cyclically variable forces are considered in load and boundary conditions. The model included combustion dynamics, contact kinetics, piston subsystem primary and secondary motions, and lubricated contact conditions to evaluate the applied forces. A comparative analysis is performed for coated and uncoated cases. Four different crown geometries are tried for selecting the best case of crown design for coated piston subsystem components. The analysis predicts better strength in coated cases compared to uncoated ones. The type-A crown design develops less stress, while the compression ring suffers the most due to elastic deformation and is more prone to fatigue failure.

Structural Performance of Additively Manufactured Cylinder Liner—A Numerical Study

Climate change is exacerbated by vehicle emissions. Furthermore, vehicle pollution contributes to respiratory and cardiopulmonary diseases, as well as lung cancer. This requires a drastic reduction in global greenhouse gas emissions for the automobile industry. To address this issue, researchers are required to reduce friction, which is one of the most important aspects of improving the efficiency of internal combustion engines. One of the most important parts of an engine that contributes to friction is the piston ring cylinder liner (PRCL) coupling. Controlling the linear deformation enhances the performance of the engine and, as a result, contributes positively to its performance. The majority of the tests to study the conformability between cylinder liner and piston were carried out on cylinder liners made of cast iron. It is possible to improve the performance of piston ring cylinder liner couplings by implementing new and advanced manufacturing techniques. In this work, a validated finite element model was used to simulate the performance when advanced manufactured materials were adapted. The deformation of the cylinder liner due to thermal and mechanical loads is simulated with five different additive manufactured materials (Inconel 625, Inconel 718, 17-4PH stainless steel, AlSi10Mg, Ti6Al4V). Simulated roundness and straightness errors, as well as maximum deformation, are compared with conventional grey cast iron liner deformation. Some additive manufactured materials, especially Ti6Al4V, show a significant reduction in deformation compared to grey cast iron, both in bore and circumferential deformation. Results show that Ti6Al4V can reduce maximum liner deformation by 36%. In addition, the roundness improved by 36%. The straightness error when Ti6Al4V was used also improved by 44% on one side, with an average of 20% over the four sides. Numerical results indicate that additive manufactured materials have the potential to reduce friction within the piston liner arrangement of internal combustion engines.

Marine Slow-Speed Engines’ Cylinder Oil Lubrication Feed Rate Optimization in Real Operational Conditions

The paper presents results of research performed to find the most suitable cylinder-liner-lubricating-oil feed rates for lubrication of long-stroke, slow-speed marine engines to reduce cylinder oil consumption and reduce engines’ maintenance costs. Obtained research data can be used to increase engines’ reliability, reduce operational costs of the vessels, and improve energy efficiency on board ships. Using analysis of under-piston scavenge drain oil, research has been performed to find the relationship between various engines’ operational factors and the wear intensity of cylinder liners and piston rings. Prediction models of the most suitable cylinder oil feed rates depend on the brand of cylinder oil and fuel actually in use, and the sulfur content in the fuel oil Verified in operation, the presented practical model can be used by engines’ operators to set up cylinder oil feed rates with satisfactory cylinder liner and piston ring wear rates and cylinder oil consumption. It is underlined that analysis of scavenge drain oil properties gives an answer whether reduction of the cylinder oil lubricating feed rate is possible, information about the quality of lubrication of cylinder liners and piston rings, and can be used as a maintenance tool to maintain the serviceability and reliability of marine slow-speed engines.

A statistical piston ring lubrication model considering the tribofilm and its effect of two-stroke marine engines

Statistical models are widely applied to marine engine simulation since the advantages of fast, efficient, and macroscopic fault. It is reported that there would be a boundary lubrication regime where the tribofilm could grow under the working condition of two-stroke marine engines. So far, there is no statistical lubrication model for two-stroke marine engines that could predict the tribofilm growth and evaluate its effect on the piston ring cylinder liner (PRCL) system. In this study, a tribofilm growth and wear model is attached to the piston ring lubrication model for obtaining the tribofilm thickness. Afterward, the coupled functional relationship between the tribofilm thickness and the comprehensive roughness is established with the help of the surface wear. Then, experimental results are employed to verify the correctness of this model. Finally, some essential simulation results, including the rate of tribofilm growth and wear, oil film thickness, and friction, could be obtained to reveal the importance of tribofilm in the lubrication performance of two-stroke marine engines.

Scuffing initiation caused by local starvation in a piston ring cylinder liner contact

Scuffing is a localized damage process caused by a sudden failure of the lu- bricating film in a sliding contact. It is associated with an important increase in temperature, friction and vibration. For the piston-ring cylinder-liner (PRCL) contact, it can lead to a complete engine failure. It is shown in this paper, that the temperature gradient generated in the contact induces the thermal Marangoni effect. The latter might then lead to a localized lack of lubricant that can initiate scuffing. On the contrary, the ring displacement along the liner redistributes the oil on the surface. This redistribution helps to avoid starvation hence reducing scuffing initiation risk. Based on the competition occurring between these two effects, a computational model was developed that predicts scuffing appearance in internal combustion engines. The origi- nality of this paper lies in presenting the complementary contribution of the Marangoni phenomenon to the scuffing initiation in the PRCL contact.

Tribological Behavior of Biomass Fast Pyrolysis Fuel and Diesel Blends

The original biomass fast pyrolysis fuel was modified by an emulsification method to obtain emulsified biomass fast pyrolysis fuel with different proportions (the content of biomass fast pyrolysis fuel in the emulsified biomass fuel was 5 wt.%, 10 wt.%, and 20 wt.%, respectively). Taking commercial 0# diesel as the blank fuel, the friction and wear characteristics of tribo-pair material from an actual piston ring–cylinder liner lubricated by the varied fuels were investigated on a reciprocating friction and wear tester, respectively. The results showed that the friction coefficient and wear of tribo-pair material lubricated with emulsified biomass fuel increased with the biomass fuel content. In the case of 5 wt.% emulsified biomass fuel, the friction coefficient was smaller than 0# diesel, and the wear was not different from 0# diesel. At the same time, the friction coefficient and wear of 5 wt.% emulsified biomass fuel increased with the reciprocating frequency when the load was constant, while they increased with the load when the reciprocating frequency was constant.

Wear Resistance of Spark Ignition Engine Piston Rings in Hydrogen-Containing Environments

We describe the external and internal hydrogen interaction on contacting surfaces in the “cylinder–piston rings” friction coupling. Under the influence of high temperatures and pressure, the oil in the combustion chamber at a temperature up to 1473 K decomposes and forms small amounts of water. External hydrogen (H2) is subsequently formed. Hydrogen removal from the piston rings reduces the heterogeneity of the structure, residual stresses, and uneven physical and chemical properties of the near-surface layers, which reduces the stress concentration and, as a consequence, results in an improvement in the performance characteristics of the surface layers of the friction couple “cylinder-piston rings” of the spark ignition engine.

Combined measurement and simulation of piston ring cylinder liner contacts with a reciprocating long-stroke tribometer

One approach to decrease emissions and improve the efficiency of combustion engines is reducing friction losses, especially in the interface between piston ring and cylinder liner. Usual model-like tribometer tests cover piston ring cylinder liner operating conditions at reversal points. This study introduces an innovative method using a new reciprocating long-stroke tribometer at component level as well as a new elastohydrodynamic simulation model enabling a greater range of operating conditions through higher velocities. The process of friction data evaluation is clarified studying crank angle resolved friction data and the effect of viscous properties is tested. The simulation allows investigating the local nominal gap height and the division of the pressure in its hydrodynamic and asperity contact contributions in detail. The results show that this combined tribological testing method obtains a quantifiable distinction between the investigated tribological systems. Additionally, a high correlation between measured friction results and simulation is achieved in general, which prospectively allows further investigations and parameter studies of reciprocating contacts.

РОЗРОБКА МЕТОДУ НЕРУЙНІВНОГО КОНТРОЛЮ ЯКОСТІ ЗАГАРТОВАНИХ ГІЛЬЗ ЦИЛІНДРІВ АВТОТРАКТОРНОЇ ТЕХНІКИ

The main part of tractor engines is the cylinder liner, which depends on the life of the machine as a whole. It is made of gray cast iron (SCh20 DSTU 1412-85) with the addition of alloying elements and subjected to the working surface of HDTV hardening. Now quality control is carried out by destructive methods (assessment of hardness, durability, structure) on specially cut templates on 1 piece. from a party to 80-100 pieces of each melting. Such control does not ensure the reliability of products, both in the quality of the base metal and heat treatment. The solution to this problem is possible by developing non-destructive quality control of each product in different periods of the process process with assessment of the properties and stress level of both the base metal (corresponding to the outer surface) and the hardened layer (inner working surface). The intensity of cylinder wear depends on the conditions of friction of the cylinder-piston ring, which are affected by the design features of the engine (power, speed, compression ratio, cooling system, as well as fuel supply and combustion, air and oil purification system), quality of fuel and oil, operating conditions and wear resistance of the cylinder material. Wear of cylinders during friction paired with a piston ring during engine operation occurs as a result of a combination of many processes occurring simultaneously: destruction of microprojections of surfaces that are destroyed by repeated plastic deformation during engagement, as well as the destruction of tired origin; setting of the material of the microprojections with subsequent deep tearing of the metal particles during the destruction of the setting unit; accumulation of abrasive particles that contribute to the intensification of wear; abrasive action of dust particles, contribution products, solid inclusions on the surface of collapsing bodies; chemical corrosion under the influence of high temperatures of gaseous products of fuel combustion; electro-chemical corrosion from the action of acids formed during the dissolution of gaseous products in condensed water vapor on the walls of the cylinders.

A comprehensive experimental study on tribological performance of piston ring–cylinder liner pair

The tribological performance of the piston ring–cylinder liner pair is affected by multiple factors. In this study, the orthogonal test method is used to comprehensively explore the influence of oil dilution, cylinder liner surface coating, and working conditions on the friction and wear of the piston ring–cylinder liner pair. The orthogonal test results show that a certain degree of oil dilution is beneficial to the performance, so the influence of oil dilution is further investigated by using the control variable method. The results show that the liner wear depth decreases first and then increases with the increase of oil dilution. Combined with the scanning electron microscope and energy dispersive X-ray spectroscopy results, it is found that the formation of tribofilm is promoted with a small amount of oil dilution under different working conditions. Meanwhile, a diamond-like carbon (DLC) coating ring and an Fe-based coating cylinder liner can significantly improve the scuffing resistance performance of the piston ring–cylinder liner pair.

Analysis of the results from a goniometer and tribotester of a diamond derivative coating on the first piston ring of an internal combustion engine

The elements creating friction pairs are described to be very difficult in terms of determining all the optimal parameters. The present research on the stability of friction pairs is focused on the surface and the top layer of the surface. The main goal is to find new design solutions and materials which would allow the vehicle to cover a lot of kilometres before the main repair of the combustion engine. The biggest structural difficulties are noticeable in friction pairs where a sliding and returning motion can be observed, which is connected with the sealing function. A typical example of such a pair is that of the piston ring-cylinder. Engineers are working on defining an additional factor that would be able to reduce the tangential force by reducing the friction coefficient in the elements of the friction pair. The molecular structure and nature of the bonds between the molecules present in the material suggest that the free surface energy may be such a factor, because it determines the tribological properties of the material, which is reflected in the stability of the units. The work performs an analysis of the results of investigations carried out by means of a goniometer in the presence of water and diodomethane, which made it possible to measure the wetting drops on the surface, owing to which the surface free energy (SFE) could be calculated. This work will include a study of the energy state of the surface of piston rings with a coating containing a diamond powder. After the analysis of the collected measurements, a conclusion regarding the potential relationship between the free surface energy and the material wear will be developed.