Piston Ring Research Articles

Анализ изменения микроструктуры компрессионных колец вспомогательного судового двигателя

Introduction. The cylinder-piston group (CPG) of a marine-type internal combustion engine is subjected to high operational loads. The reliability, durability and efficiency of the engine depend on the proper operation of the CPG. The change in the direction of piston movement and the lack of lubrication caused by the spraying of lubricant during operation, lead to increased wear of the moving package of piston rings. Having determined the factors influencing the changes in the structure of the metal during operation, it can be taken into account in the manufacturing technology and hardening of these parts. The subject of the study: the object of research is the used-out upper and lower compression rings of the cylinder-piston group of the HIMSEN 4H21/32 auxiliary marine engine. Purpose of the work is to consider the change in the structure and microstructure of the material of the compression piston rings of the HIMSEN 4H21/32 auxiliary marine engine arising as a result of operation; to compare the results of evaluating microstresses and deformations of the surface layer of parts by metallographic methods and X-ray diffraction analysis for various operating conditions of the upper and lower compression rings. Methods. Metallographic and X-ray methods were used in the study. The conditions of X-ray photography are described; X-ray diffraction analysis was carried out on a Dron-3M diffractometer. Residual microdeformations were determined, as well as the sizes of coherent scattering regions (D) and the density of dislocations on the surfaces of the samples. Results of the work. The results of metallographic and X-ray diffraction analysis (XRD) are presented. The residual macro- and microstresses and the sizes of the coherent scattering regions (D) of the surface layer of compression rings are determined. The results of X-ray diffraction analysis are comparable with the results of metallographic studies, and the convergence of the results is observed. Scope of the results application: the results of the study can be used in the selection of manufacturing technology for compression rings of marine internal combustion engines (MICE). Conclusions. It is advisable to evaluate changes in the manifestations of the stress state of cast iron under the influence of various factors. This will allow selecting the optimal technology for manufacturing compression rings to ensure the reliability of its operation. Ring quality control by various methods of structure assessment also makes it possible to predict the conditions of destruction of compression rings during operation. An increase in the degree of defectiveness of the upper ring occurs due to various kinds of deformations of the crystallites. As a result of inelastic deformations during ring operation, the resulting dislocations cause strong mechanical stresses.

Sliding wear mechanisms and speed-load wear map of cylinder liner and piston ring under lubricated conditions

Sliding wear mechanisms and speed-load wear map of cylinder liner and piston ring under lubricated conditions

Design of parameters for running-in cylinder liner piston rings based on running-in attractor

Purpose The purpose of this study aims to shorten the running-in time and improve the running-in quality of cylinder liner piston rings (CLPRs), the running-in tests were carried out and running-in parameters of CLPRs were designed based on running-in attractor theory, which can guide the choice of optimal working conditions for other friction pairs. Design/methodology/approach The running-in state and time under different working conditions are identified by the evolution law of the running-in attractor phase trajectory and fractal and chaotic characteristic quantities. The CLPRs running-in tests under different conditions were conducted and the friction signals were collected. The constructed phase trajectories and calculated chaotic parameters of the running-in attractor are obtained and the running-in state and time are identified by the evolution law of phase trajectories and chaotic characteristic quantities. The running-in quality is obtained by the surface morphology fractal dimension and characteristic roughness parameters. Findings The running-in parameters for short running-in time and good running-in quality are designed based on the fractal and chaotic theory and the optimal solution method are used to verify the results through the single objective or multi-objective optimization, and the corresponding optimal running-in parameters are obtained. Originality/value The optimal working condition parameters obtained from the design have guiding significance for the selection of CLPR running-in parameters, and this work can provide ideas for the other friction pairs. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0179/

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.

Crystalline Carbon Deposition on Piston Ring Substrates and Its Effects on Tribological Characteristics, Engine Performance, and Emissions

Electron cyclotron resonance‐chemical vapor carbon deposition technique was altered via incorporation of nitrogen gas in the methane (CH4)‐based plasma, thermal annealing of the substrates, and Arduino‐controlled sample rotating mechanism to bombard the contact surface of the piston ring samples. By placing the substrates very close to the plasma gun, various carbon‐based structures including graphene oxide, nanodiamond, and reduced graphene oxide were successfully deposited. The formed structures were characterized via scanning electron microscopy, atomic force microscopy, Raman spectroscopy, X‐ray diffraction, and energy dispersive X‐ray. Related tribological analyses such as surface hardness‐roughness, coefficient of friction (COF), and wear rate were also carried out on the coated surfaces. The morphology and chemical composition of the worn surfaces were observed via SEM and EDX. The coated samples were installed in a small spark‐ignition engine to determine the effect of coating on brake power (Pe), specific energy consumption (β), carbon monoxide (CO), and unburned hydrocarbon (UHC) emissions. Very promising results of 14% increase in surface hardness, 11% reduction in β, 15% enhancement in Pe, 50% decrease in COF, 12.5% and 9% improvements in CO, and UHC emissions were obtained.

Research on weak appearance defect detection method for engine piston rings based on 3D vision

Abstract As a critical engine component, the appearance quality of piston rings directly affects engine performance and lifespan. Subtle defects like minor chipping, cracks, and scratches can significantly impact engine safety and durability. Traditional 2D image processing and AI-based methods struggle to detect these defects, being prone to interference and resulting in high false positive and negative rates. This paper introduces a 3D vision-based detection method, which captures detailed surface morphology to improve defect detection accuracy. Experimental results demonstrate that this approach effectively reduces false positives and negatives, significantly enhancing detection accuracy.

Ni-P SiC composite coatings on piston rings by plate and bumper technique and its tribological properties

Breakdown of piston rings in the automotive sector due to wear, corrosion and high temperatures is common. Conventional hard chrome and chrome ceramic coatings with hexavalent chromium possess environmental risks due to its carcinogenic effects. Nickel-phosphorus (Ni-P) plating is not hazardous and hence silicon carbide (SiC) uniformly distributed in Ni-P coating by plate and bumper method is made as an eco-friendly and cost-effective approach. This Ni-P SiC composite coating provides high hardness, wear resistance, corrosion resistance and improved friction resistance due to the uniform distribution of the SiC composite particles. The amorphous Ni-P coating is converted to nickel phosphide intermetallic crystalline form during the heat treatment at 300 °C and is confirmed by XRD. The heat treatment also increases the microhardness in the rage of 810 to 1015 HV for Ni-P SiC composite coating. This method significantly improved the mechanical properties of piston rings by ∼ 5 to 6%.

Molecular dynamics study of the scratching property of the tetrahedral amorphous carbon coating on the piston ring

In order to reduce friction and wear of the piston ring-cylinder liner system of the internal combustion engine, the tetrahedral amorphous carbon (ta-C) coating on the piston ring is considered. The scratching properties of the ta-C coating and diamond ball are studied by molecular dynamics simulation. The atomic configuration, surface morphology, RMS roughness, friction force, coefficient of friction, wear rate, and normal stress of the ta-C coating are analysed under different scratching depths, substrate temperatures, and scratching velocities. The interatomic interactions are described using the second nearest-neighbour modified embedded-atom method potential, as well as Tersoff potential and Lennard-Jones potential. The simulation results show that the ta-C coating exhibits excellent scratching properties. The scratching depth has a significant effect on the scratching property of the ta-C coating, while the substrate temperature and scratching velocity have a relatively small effect.

Theoretical analysis of the piston ring-pack for predicting friction and power loss in an internal combustion engine

The piston ring is considered an essential element in the operation of the internal combustion engine to improve its efficiency and reduce its emissions. It is resistant to high temperature and high-pressure gases in the combustion chamber. A one-dimensional analysis method of lubrication between piston rings and cylinder liner in mixed lubrication conditions is developed in this article by using the GT-Suite simulation software. We applied the finite difference numerical method to solve the Reynolds equation to obtain the variation during an engine cycle of the following parameters; film thickness, frictional force, and power loss. The solution results presented can be used to improve the design of the piston ring pack in internal combustion engines and is available for industry usage.

The Influence of Iron Content on the Porosity of AlSi9 Alloy Intended for Alfining Piston Ring Inserts.

Due to its tendency to increase the power of engines, improving their reliability and operational efficiency, the compression ring in combustion engine pistons is embedded in a cast iron insert, which is subjected to the process of "alfining". This involves covering the insert with an Al-Si alloy, which increases the iron content. Research has shown that the β-Al5FeSi phases crystallizing in the area of the insert-piston connection are the main cause of an unstable connection between the silumin casting of the piston and the ring insert. Their unfavourable lamellar morphology and large dimensions are the main causes of weakening in the connection between the insert and the piston, resulting in an unacceptable number of defective products. It has also been found that up to approx. 0.59 wt.% Fe, the pore volume fraction is very small (up to 3%), and there is no correlation. However, after exceeding this value, both the volume fraction of the β-Al5FeSi phase and the number of pores increase monotonically to values of approximately 18% and 14%, respectively, and the correlation between the examined features is statistically significant. These results were compared with known theories of the influence of iron on the porosity of Al-Si alloys, showing that the precipitates of the β-Al5FeSi phase are more important in the porosity fraction than the two-layer oxide films called "bifilms". This research was carried out and verified under industrial conditions in one of the largest piston foundries (Federal-Mogul Gorzyce sp. z o.o., F-MG) on a separate line intended for alfining ring inserts intended for combustion pistons.

Detection of Piston Ring Deficiency in The Assembly of Automotive Ball Joint and Tie Rod End Parts

In today's intensely competitive environment, businesses strive to optimize production efficiency to reduce costs, increase profitability, and ensure customer satisfaction. This focus on efficiency and quality enables businesses to operate more effectively, gain a competitive advantage in the market, and move towards sustainable growth. This study uses image processing techniques to detect missing segments in the assembly of ball joints automatically. In the automotive industry, performing quality control of critical components before assembly and detecting and classifying the defective ones is essential. Many quality control methods can be applied with existing technologies. This paper proposes an automatic real-time control based on image processing techniques to detect ball joint missing segments, a common defect in the automotive industry. In the company, operators perform defect detection by visual inspection. In this system, production continues in cases where the operator cannot detect the defect. This system aims to detect the errors made by the operator during the assembly operations and provide instant feedback. The developed system uses OpenCV library algorithms that are highly accurate in detecting defects in manual assembly processes so that missing components are removed from the production chain, and production quality is significantly improved. Accuracy is over 94% when identifying missing segments, about 30% better than traditional methods. In tests, 1200 ball joints were run through the system, resulting in 1150 defects being correctly identified and removed from the production line. Accuracy is high thanks to the application of various image processing techniques such as grayscale conversion, edge detection, and shape recognition. This also provides real-time feedback to the operator so the system can reduce detection and response time from 15 seconds to 5 seconds. This increases production speed and reduces the error rate in manual assembly processes by 20%. This paper also highlights the potential of image processing technology in manufacturing. It will contribute to improved quality control mechanisms to increase the reliability and efficiency of production lines in the automotive industry.

Analysis of research on abrasive wear of vermicular cast iron

The paper analyzes and discusses the orientations of researchers regarding the abrasive wear of vermicular cast iron. The analysis was related to the shape of graphite occurrence in cast iron, the change in the matrix and the change in chemical composition, and the impact of these changes on wear under dry and wet friction conditions. Compact graphite cast iron is tested for use in machine and device parts such as cylinders and piston rings, discs, shafts and bearings. It was found that the improvement of abrasive wear of vermicular cast iron is influenced, among others, by the shape of graphite, the alloy addition in the form of tin, as well as the change of the matrix in vermicular cast iron to an ausferritic one. Summarizing the analysis of research carried out by a number of authors, it would be necessary to continue research on the abrasion resistance of this material, and it would also be advisable to include issues related to the warping and deformation of samples as a result of heating and cooling of cast iron.

Wear Characteristics Caused by Ti3AlC2 Particles under Impact-Sliding Conditions in Marine Engine

With the marine industry’s demands for carbon reduction and increased reliability, the friction and wear performance of marine engines is becoming increasingly important. MAX phase materials show great potential in marine engine tribopair materials due to their unique microstructure and performance. The typical MAX phase material Ti3AlC2 was combined with MoDTC and added to the lubricant containing ZDDP additive for the tribopair composed of chromium-based ceramic composite coated steel (CKS) piston rings and cast iron cylinder liners under impact-sliding conditions. Compared to Ti3AlC2 alone, the friction coefficient and wear depth of the designed composite additive MoDTC/Ti3AlC2 were reduced by 36.9% and 41.4%, respectively. The worn surface lubricated with the Ti3AlC2/MoDTC composite additive showed fewer scratches with significantly less plastic deformation and clearer honing grooves. The multi-component tribofilm containing FeS, MoS2, MoO3, ZnO, TiO2, Al2O3, unoxidised particles, short-chain phosphates, and some ZnS was present on the worn cylinder liner surface. The synergistic effect of Ti3AlC2, MoDTC and ZDDP additives in the lubricant can isolate the mutual contact, generate a solid tribofilm and reduce the scratching. This can provide some guidance for the development of high-performance lubricant additives under impact-sliding conditions.

Evaluation of Tribological Properties of Different Coatings on Automotive Piston Rings: A Review

Friction and wear play crucial roles in automotive engine performances and their efficiency. Overall, 40% of fuel power loss occurs in friction of various components of the engine. Frictional loss between piston rings and cylinder liner assembly contributes major loss of fuel power in the automotive engine and it is about 15% of total fuel power loss occurs due to friction. In the present scenario, thin film coating techniques are in trend to enhance the mechanical and tribological properties of machine components. In this paper, different types of wear-resistant, corrosion-resistant, and antifriction coating materials and their characteristics are discussed. Also, carbon-based coatings, nitride coating, carbide coating, oxide coating, and the intermixing of counterparts of coating material to form a composite coating, multilayer coating, and varying their percentage elemental composition composite are reviewed and compared. The synergistic effect of coating with texturing over the piston ring is discussed. Finally, recent developments and new possibilities of coatings that can be employed on piston rings are briefly discussed.

Limited Critical Review of Simplified Static Conformability Models of Piston Rings

The article traces the origin of several generalized conformability bounds for split and splitless piston rings used in the automotive industry to troubleshoot and better design piston engines and compressors for lesser emissions and oil consumption by presenting an irregular power cylinder bore shape through individual Fourier waveforms of a different order. The work also elucidates the origin and capabilities of the prematurely forgotten specialized ring-bore contact models of the 1940s for single-order bore deformation (round and oval), according to which a ring-bore seal breach occurs only near the ring ends and emerges with any bore deformation. With the aid of this information, the report explains that the split ring generalized models’ theoretically defined conformability bounds are largely conventional categories that become sufficiently compelling engineering tools only by adapting the models to the experimentally observed or analytically asserted ring-bore clearances near the ring ends and considering the ring and bore design and production deviations from the theoretical models. The study further demonstrates that different researchers’ semiempirical versions of these bounds were spinoffs from the author’s analytical model of 1990. The article’s information helps engineers design piston rings and the associated components with better functional and tribological properties.

Tribofilm distribution and tribological analysis of piston ring-cylinder liner interfaces under realistic engine conditions

The study investigates tribofilm distribution and tribology performance on piston ring-cylinder liner surfaces under realistic internal combustion (IC) engine conditions. By examining the effects of load, temperature, and oil film thickness ratio, the research reveals that the tribofilm is significantly greater on the cylinder liner surface compared to the piston ring surface. The findings highlight that a specific excitation pressure is necessary for tribofilm formation. An oil film thickness ratio of 1.8041 is evaluated as an accurate boundary for tribofilm distribution on the cylinder liner surface. These insights provide valuable data for designing piston ring-cylinder liner interfaces and improving IC engine performance.

Tribological Comparison of Coatings Produced by PVD Sputtering for Application on Combustion Piston Rings

This article compares the tribological performance of coatings produced by PVD sputtering. Transition metal dichalcogenide (TMD) coatings doped with carbon (WSC and MoSeC) and nitrogen (WSN and MoSeN) and a conventional diamond-like carbon (DLC) coating are compared. The tribological evaluation was oriented towards the use of coatings on piston rings. Block-on-ring tests in a condition lubricated with an additive-free polyalphaolefin (PAO 8) and at temperatures of 30, 60, and 100 °C were carried out to evaluate the coatings in boundary lubrication conditions. A load scanner test was used to evaluate dry friction and scuffing propensity. In addition to WSN, all other TMD coatings (WSC, MoSeC, and MoSeN) exhibited lower friction than DLC in dry and lubricated conditions. The study reveals that WSC, among TMD coatings, offers promising results, with significantly lower friction levels than DLC, while demonstrating reduced wear and a lower risk of metal adhesion. These findings suggest that WSC may be a viable alternative to DLC in piston rings, with potential benefits for reducing fuel consumption and increasing engine durability.

REFINING THE EMPIRICAL MODEL OF THE HEAT TRANSFER BOUNDARY CONDITIONS OF THE PISTON OF A HIGH-SPEED DIESEL ENGINE

The level of temperature of ICE pistons is a factor that greatly affects their reliability. Therefore, the need to simulate the temperature state of pistons with sufficient accuracy and minimal allocation of resources and time exists in research and during design. Primary approaches for determining the boundary conditions of the problem of thermal conduction of the piston on the basis of criterion equations, high-level mathematical models, and empirical models are considered. The latter ones have become widespread by virtue of simplicity and ease of use in practice; their usability is limited to a certain set of operating modes of one engine or a few ones of a similar design. On the basis of data from four series of experimental tests for a well-studied diesel engine 4ChN12/14 the existing empirical models of boundary conditions, suitable for identifying the temperature state of the piston only within the respective separate series separately, are refined in the paper. Processing of the data set on the measured temperatures in the control zones of the piston was performed, and linear function approximations were found that satisfactorily describe the effect of diesel power on the specified temperatures. The model of boundary conditions for a set of eighteen separate regions on the surfaces of the piston was proposed, which takes into account the dependence of the piston temperature state on the brake power of the ICE, the crank angle of the start of fuel injection, and the conditions of cooling the piston with oil. The influence of the heat insulation layer on the piston crown surface on the heat transfer was accounted for by introducing an additional thermal resistance term into the boundary condition equations. The model made obtaining the temperature field of the piston possible in simulation that is consistent with the results of all series of experiments in the control zones of the piston periphery, the edge of the combustion chamber, the vicinity of the groove of the first piston ring, the cooled surface opposite to the combustion chamber, and the piston skirt. The importance of a gradual change in the temperature of the oil and coolant during the transition of the internal combustion engine from one mode of operation to another regarding the temperature state of the piston is demonstrated. Taking the temperatures of oil from previous modes of operation into account is recommended during the analysis of engine transient processes.

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.

Tribological properties under dry and lubricated sliding conditions of TiSiN and AlTiCrN coatings deposited on gray cast iron

In internal combustion engines, the majority of friction losses and wear occur between the cylinder liners and piston rings. Hard coatings applied to cylinder liners can increase the efficiency of internal combustion engines by improving tribological properties. The gray cast iron cylinder liner was coated with TiSiN and AlTiCrN employing the cathodic arc deposition process. The coatings were examined using nanoindentation tests, scratch tests, an optical profilometer, a scanning electron microscope, an X-ray diffractometer, and energy dispersive analysis to assess their hardness, adhesion, and structural characteristics. The reciprocating test was carried out to assess the coatings' wear and friction characteristics under lubricated and dry sliding with a ball at varying normal loads. The hardness of the TiSiN and AlTiCrN coatings was 45 GPa and 18 GPa, respectively. The cohesion strength, adhesion strength, and crack propagation resistance of AlTiCrN coating were approximately 2, 1.3 and 2.5 times higher than those of TiSiN coating, respectively. Both coatings exhibited remarkable wear performance at high normal loads. Under dry sliding conditions at 25 N normal load, the wear rate of AlTiCrN and TiSiN coatings were nearly 33 and 20 times, respectively, lower than the uncoated substrate. Under dry sliding conditions, the TiSiN coating exhibited the lowest wear rate at low normal loads (5 N and 15 N), while the AlTiCrN coating performed best at high normal loads (25 N). In lubricated sliding conditions, the AlTiCrN coating consistently showed the lowest wear rate across all normal loads.