Piston Ring Liner Research Articles

Tribo-dynamic modeling method and application to three-dimensional flexible PRL system

Research on the tribo-dynamics of the piston-cylinder liner (PCL) and piston ring-cylinder liner (PRCL) is vital due to their role in generating over 50 % of total engine friction loss and the impact on carbon emissions. Traditional studies, hindered by the structural and functional differences between pistons and rings, required separate simulation models, often overlooking crucial coupling characteristics. A unified tribo-dynamics modeling method for the piston-ring-liner (PRL) system is proposed in this paper, integrating the ring pack and piston into one multi-body system. This article models with global coordinates, unifying the form of governing, film thickness, and load equations of discontinuous lubrication domains for more efficient dynamics-lubrication coupling. The described method is applied to a marine engine, and the new tribology characteristics discovered after calculations are exhibited. It shows how piston deformation impacts ring tribology, indicating that increased profile height reduces the squeezing effect by allowing more ring movement. Additionally, ring assembly position significantly affects tribology parameters' circumferential distribution. Installing the ring with the end gap facing the piston pin side should be avoided, as it maximizes the negative impact of elastic force and secondary motion, deteriorating lubrication.

An Examination of Effect of Impact on Four Stroke 4 Cylinder Petrol Engine using Different Engine Oil

In the gas powered motor not practically everything moved to the cylinder from the gases contained inside the chamber the Demonstrated work is accessible at the drive shaft for real work.. The grinding delivered because of PRA(piston ring assembly) has a significant commitment altogether frictional misfortunes of the motor. The piston ring gathering is predominant wellsprings of the motor scouring force. This work endeavors to assess the frictional power at the piston ring liner gathering by utilizing different motor oil. To assess the frictional power a model ready by the YUKIO is thought of. The exploratory work was led on a four stroke 4-chamber SI motor from speed range from 1500 rpm to 3000 rpm. It is seen that the greatest worth of the frictional power is higher for the ointment SAE30W which might reason for higher wear of the rings. The utilization of grease SAE15W in the given arrangement would make less wear of piston rings due diminish frictional powers. Key words:- Piston Ring Assembly, Gas powered cycle, friction, wear, SAE.

Investigation of friction properties in the piston-cylinder liner region of a single-cylinder compressed air engine using the GT-SUITE program

Dependence on nonrenewable fuels continues to a great extent today. Overuse of fossil fuels has brought along various environmental problems. In order to reduce such problems, compressed air engines have developed significantly during the last 20 years. Compressed air engines are environment-friendly engines that do not use fossil fuel and achieve expansion using compressed air. It is of great importance for engine efficiency to decrease friction losses of piston engines. There are not many studies in the literature focusing on friction manner of piston ring liner parts of compressed air engines with a piston. In this article, the transformation of a four-stroke gasoline engine with 388 cm3 displacement into a compressed air engine has been carried out and the friction manner between piston cylinder liner has been modeled with the help of GT-SUITE program using in-cylinder pressure-cylinder volume (P-V) data obtained from different engine loads under operating pressure of 12 bar and geometrical size of the engine. It has been determined according to the results of the simulation that asperity friction losses have not changed significantly in top dead center and bottom dead center regions due to low testing speed, and hydrodynamic power losses have occurred in the middle of the course. Lack of combustion reactions in such engines has resulted in compression leakages and unavailability of a quality oil film layer. Since there are no combustion reactions, the eccentric movement of the pistons of the compressed air engines is changed by the lubricating oil, engine speed, compression leaks, and viscosity parameters.

Shear-area variation: A mechanism that reduces hydrodynamic friction in macro-textured piston ring liner contacts

Using a reciprocating rig to simulate the piston ring-cylinder liner contact, we show that macro-scale surface texture yields friction reductions in the hydrodynamic regime of up to 35%. Based on these experimental observations, we put forward a new macro-texture induced friction reduction mechanism and validate it through theoretical 1D modelling. This “Shear-Area Variation” mechanism involves macro-texture reducing both the sheared contact area (acting to decrease friction) and hydrodynamic load support/lubricant film thickness (acting to increase shear-rate and hence friction). Provided the oil film is thick enough to prevent asperity contact, the area reduction effect dominates the friction response. This has implications for machine efficiency improvements, as friction is reduced around mid-stroke where sliding speed and energy dissipation is greatest. It also complements the majority of surface texture research which involves micro-scale texture that is only effective at low speeds in the mixed and boundary regimes (around top and bottom- dead centre).

Potential of CuS and CuO nanoparticles for friction reduction in piston ring–liner contact

ABSTRACT An experimental study on the use of Cu nanofluids as engine oils for reduction of friction in piston ring–liner contact is presented. The Cu nanofluids were prepared using CuS and CuO nanoparticles and blending them in 0.1–6% concentration by weight in the commercial engine oils. The Cu nanoparticles were synthesised and characterised after mixing with the lubricant for their physico-chemical characteristics. The experiments were performed on a reciprocating tribo-tester using actual piston rings and the liners as test specimens. Experiments were performed to investigate the effect of nanoparticle concentration with the change of contact loads and reciprocating frequency on the coefficient of friction. The study reveals that the Cu nanoparticles blended in the engine lubricating oils can significantly reduce friction between piston ring–liner contact, desirable for fuel economy improvement. The Cu nanoparticles are compatible with base lubricants and result in significant friction reduction. The CuS nanoparticles performed significantly better than the CuO nanoparticles.

Research on the Characteristics of Piston Ring-liner Friction Lubrication Based on Acoustic Emission

Research on the Characteristics of Piston Ring-liner Friction Lubrication Based on Acoustic Emission

Effects of Ring Pack Friction Heat on Temperature Fields of Piston Set-Liner

To investigate the temperature fields of piston set-liner under the friction heat of ring pack, it is established a friction heat allocation model of ring pack based on the heat transfer theory of semi-infinite body. In this model, the piston ring, lubrication film and liner are treated as a three-layer medium. Furthermore, the distribution model of ring pack friction heat, the unsteady heat-mixed lubrication and friction model of piston ring-liner, and the heat transfer model of piston assembly-liner are also built and coupled with the allocation model to develop a coupled heat transfer model of piston set-liner. Employing the model for 6110 diesel engine, the effects of ring pack friction heat on the temperature fields of piston set-liner are simulated. Numerical results demonstrate that the friction heat allotted to the piston ring, lubrication film and liner accounts for nearly 47 %, 21 % and 32 % of ring pack friction heat, respectively. Due to the effects of friction heat, the maximum temperature rises on the piston ring, piston and liner surfaces run approximately up to 8.5 °C, 5 °C and 5 °C, separately. The established allocation and distribution models related to friction heat in this paper can be applied to any type of piston set-liner and provide the theoretical foundation for the optimal design of piston ring-liner.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 4—Piston Rating, and Fuel Injection Equipment Issues

AbstractThis study investigated the use of biodiesel (B100) and baseline diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel's compatibility with modern common rail direct injection (CRDI) fuel injection equipment (FIE) and evaluate biodiesel's long-term durability/compatibility with engine components. Two identical vehicles were fueled with biodiesel (B100) and baseline mineral diesel for 30,000 km field-trials on highway under identical operating conditions. Exhaustive experimental results from this series of tests are divided into four segments. The fourth and the last paper of this series compares the effects of long-term usage of biodiesel on piston deposits and FIE components compared to baseline mineral diesel. A key challenge for improving engine performance and fuel economy is the reduction of frictional losses, primarily at the piston ring–liner interface, which accounts for majority of frictional losses. Piston rating was done for the two vehicles after the conclusion of field-trials and it revealed that rating of different piston sections was ∼5–15% superior in case of biodiesel-fueled vehicle compared to that of diesel-fueled vehicle. Performance of FIE components such as fuel filter, fuel injectors, and fuel pump was assessed after the conclusion of field-trials. Pressure drop at different fuel flow-rates across the fuel filter was measured for assessing the fuel filter blockage. Pressure drop across biodiesel filter was ∼30% higher than diesel filter after 10,000 km usage but almost twice after 15,000 km usage. These experimental results indicated that some additional technical measures should be taken by automotive manufacturers to offset these technical challenges before biodiesel is adapted on a large-scale in modern CRDI vehicles.

The compression ring profile influence on hydrodynamic performance of the lubricant in diesel engine

For different operating conditions of an internal combustion engine, the piston–ring–liner compartment represents one of the largest sources of friction and power losses. The aim of this article is to evaluate the effect of the compression ring profile on the main tribological performance of the lubricant in a four-stroke diesel engine. A one-dimensional analysis was developed for the hydrodynamic lubrication between the compression piston ring and the cylinder wall. A numerical method was applied to analyze the influence of different ring geometrical designs during the working cycle on oil film thickness, frictional force, and power losses. Our predicted results were validated with the Takiguchi data of a previous study, and they have shown a good agreement. The results in the current analysis demonstrated that the ring geometry profile, the engine speed, and load have a remarkable effect on oil film thickness, friction force, and friction power losses between the top ring and cylinder liner. Therefore, it would help in reducing friction as well as making a contribution to the improvement of engine performance such as torque, efficiency, and fuel consumption.

Contact modeling with a finite element model in piston ring‒liner conjunction under dry conditions

PurposeThe purpose of this paper is to focus on the creation of an isothermal elastic ring-liner model to highlight, through stresses, the occurrence of the plastic deformation in certain crank angles under extreme dry lubrication conditions.Design/methodology/approachThe stresses that are exported from this analysis are pointing out not only the necessity for an elastoplastic model to be created, but also the importance of predicting the correct friction coefficient, as pointed out by both the contact surface stress and that in depth of the two bodies in contact.FindingsThe comparison between the finite element model and the adhesion mathematical model of Johnson, Kendall and Roberts seals the importance to calculate the interaction forces, acting on the common solid surface, in the pursuit of defining a propriate contact patch. Additionally, a three-dimensional ring model is built, highlighting the importance of the modeling surface’s micro asperities for a solid stress analysis. Also, numerical experiments are conducted, in contact with the cylinder and a piston ring made of an iron alloy and of two different plating materials, such us Chromium (Cr) and Chromium‒Nickel Alloy (CrN). The ability to calculate the stress concentration factor is also described.Originality/valueA three-dimensional ring model is built, highlighting the importance of the modeling surface’s micro asperities for a solid stress analysis. Also, numerical experiments are conducted, in contact with the cylinder and a piston ring made of an iron alloy and of two different plating materials, such us Chromium (Cr) and Chromium‒Nickel Alloy (CrN). The ability to calculate the stress concentration factor is also described.

3D heat transfer, lubrication and friction coupled study for piston ring-liner on diesel engines

The piston ring and liner of internal combustion engines are generally used under increasingly harsh conditions. To investigate the mechanisms affecting the work ineffective, the coupled heat transfer, lubrication and friction model between the piston ring and liner is proposed by coupling the gas, piston set-liner, lubrication film and coolant. In this model, the temperature variation of lubricant, the gas blowby, the surface roughness, the rupture position and the non-axial symmetry of oil film are considered. The coupled heat transfer, lubrication and friction simulation is carried out for 6110 diesel engine, and the temperature fields of piston set-liner along with the corresponding lubrication and friction curves are obtained. The simulated results are verified by comparing with the temperature experiment of piston.

Methodologies to Compare IC Engine Power Assembly Interface Materials

To meet the needs of higher power, lower weight and better emissions IC engines, component manufacturers develop new materials, coatings and surface technologies (e.g. surface texture). In this paper methodologies have been developed for comparing & ranking interface materials with custom-built rigs built in GE Global Research, Bangalore for large sized IC engines. This work will discuss the three methodologies developed using: i) Journal Bearing Rig ii) Piston-Liner Rig and the iii) Valve-seat rig. The Journal bearing Rig can be spun to engine linear speeds with lubricant heated to engine oil temperature. The loading is performed using a hydraulic system. Seizure, steady state wear and start stop tests can be performed on this rig. The piston liner rig can accommodate a section of the liner and ring from an actual engine. The combination of the pneumatic mechanism and the 2-axis load cell can load and measure the normal load & frictional load. The piston ring-liner simulates interface hot engine temperatures and contact pressures at TDC/BDC. Scuffing & wear tests can be performed with this test rig to compare scuffing limits and steady state wear rates. The valve-seat rig fixture is built within a MTS frame and can accommodate small sections of the actual engine valve and seat. Normal load and the fretting stroke is simulated using MTS hydraulic system A furnace is used around the fixture to simulate higher temperatures. Case studies comparing & ranking different coatings/repair coatings and oil additives etc. will be presented in this work to showcase the effectiveness of the methodology. Tests using this methodology can be typically performed in 10 % of time & cost of actual engine test.

Evolutions of cylinder liner surface texture and tribological performance of piston ring-liner assembly

Abstract This paper presents the results of the tribological experiments conducted using an oscillating wear tester under lubricated conditions. Specimen from piston ring slid against counter-specimen from cylinder liner. Various surface textures of cylinder liners resulted from honing and/or plateau honing. Tests were carried out for two normal loads of 100 and 300 N at a temperature of 80 °C, the stroke was 3 mm, the frequency was 10 Hz. Each experiment was divided into four time intervals. During breaks between the particular parts of the test, the surface topography of cylinder liners was measured by a white light interferometer. It was found that an increase in the normal load led to an increase in changes of the liner surface textures.

A mass-conserving algorithm for piston ring dynamical lubrication problems with cavitation

PurposePiston ring dynamic problem plays an important role in the lubricant characteristics of a reciprocating engine, which lead to engine wear and the increased consumption of lubricating oil. A cavitation analysis of the piston ring lubrication with two-dimensional Reynolds equation has rarely been reported owing to the complex working condition. The purpose of this study is to establish a precise model that can provide guidance for the design of the piston ring.Design/methodology/approachIn this paper, a cavitation model and its effect on the piston ring lubrication was studied in a simulation program based on the mass-conserving theory which is solved by means of the Newton–Raphson method. In this study, some models such as mixed lubrication, asperity contact, blow-by/blow-back flow and cavitation have been coupled with the lubrication model.FindingsThe established model has been compared with the traditional model that deals with cavitation by using the Reynolds boundary condition algorithm. The cavitation zone, pressure distribution and density distribution between the piston ring and the cylinder have also been predicted. Studies of the changing trend for the pressure distribution and the cavitation zone at few typical crank angles have been listed to illustrate the cavitation changing rule. The analysis of the results indicates that the developed simulation model can adequately illustrate the lubrication problem of the piston ring system. All the analyses will provide guidance for the oil film rupture and the reformation process.Originality/valueA two-dimensional cavitation model based on the mass-conserving theory has been built. The cavitation-forming and -developing process for the piston ring–liner lubrication has been studied. Non-cavitation occurs in the vicinity of top dead center and bottom dead center. The non-cavitation period will be longer in the vicinity of 360° of crank angle. The density distribution in the cavitation zone can be obtained.

Piston ring–liner lubrication and tribological performance evaluation: A review

Internal combustion engines are at present used as the major power sources for transportation and power generator. Improvement of the internal combustion engine efficiency is expected due to strict environmental standards and energy costs. Any reduction in oil consumption, friction power losses and emissions results in improving engines’ performance and durability. Automotive industries have intense passion to increase engines’ efficiency to meet the fuel economy and emission standards. Many studies have been conducted to develop reliable approaches and models to understand the lubrication mechanisms and calculate power losses. This review paper summarizes the synthesis of the main technical aspects considered during modeling of piston ring–liner lubrication and friction losses investigations. The literature review highlights the effects of piston ring dynamics, components geometry, lubricant rheology, surface topography and adopted approaches, on frictional losses contributed by the piston ring-pack.

Mutual influence of plateau roughness and groove texture of honed surface on frictional performance of piston ring–liner system

The cylinder liner surface finish, which is commonly produced using the honing technique, is an essential factor of engine performance. The characteristics of the texture features, including the cross-hatch angle, the plateau roughness and the groove depth, significantly affect the performance of the ring pack–cylinder liner system. However, due to the influence of the honed texture features, the surface roughness of the liner is not subject to Gaussian distribution. To simulate the mixed lubrication performance of the ring–liner system with non-Gaussian roughness, the combination of a two-scale homogenization technique and a deterministic asperities contact method is adopted. In this study, a one-dimensional homogenized mixed lubrication model is established to study the influence of groove parameters on the load-carrying capacity and the frictional performance of the piston ring–liner system. The ring profile, plateau roughness, and operating conditions are taken into consideration. The main findings are that for nonflat ring, shallow and wide groove textures are beneficial for friction reduction, and there exists an optimum groove density that makes the friction minimum; for flat ring, wide and sparse grooves help improving the tribological performance, and there exists an optimum groove depth that makes the friction minimum.

Effects of honed cylinder liner surface texture on tribological properties of piston ring-liner assembly in short time tests

The experiments were conducted using an oscillating wear tester under lubricated conditions. Specimens were cut from cylinder liners made of gray cast iron. As the results of honing and/or plateau honing various surface textures of cylinder liners were obtained. Counter-specimens were cut from chromium-coated compression ring. Short time tests were carried out at temperature of 80°C, stroke was 3mm. The other operating parameters, like normal load and frequency varied. Before and after tests surface topographies of liners were measured by a white light interferometer. It was found that one-process textures led to smaller coefficients of friction than two-process topographies for test duration of 0.5h. The frictional resistance increased when honing angle increased.

Numerical investigation of tribological performance in mixed lubrication of textured piston ring-liner conjunction with a non-circular cylinder bore

A number of inevitable factors distort the liner circular bore, resulting in asymmetry of piston ring-liner (PRL) contact in the circumferential direction. The limited conformability of a piston ring causes a gap in PRL contact, which has significant effect on the tribological performance of the interface. Recent developments in ring surface modification through laser surface texturing have shown promising results in improving tribological characteristics. Analyses of a textured piston ring are often based on ideal circular liner bore, which is contrary to actual engine operating conditions. In this study, asymmetric PRL contact of a textured piston ring in a distorted bore is considered, and the 2D Reynolds equation is solved with a mass-conserving cavitation algorithm. In addition, asperity interaction in mixed lubrication, axial ring dynamics, variable ring conformability, and realistic engine oil rheology are considered in the investigation of tribological performance of a non-axisymmetric textured PRL interface. Results show that optimized surface textures improve the tribological performance of a PRL interface, whereas textures with large lateral aspect ratios have a detrimental effect. The surface texturing-induced increase in oil transport to the combustion chamber remains minimal.

Investigation of friction characteristics in segmented piston ring liner assembly of IC engine

Summary The friction at the piston ring cylinder liner assembly (PRLA) is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

Optimizing the tribological performance of textured piston ring–liner contact for reduced frictional losses in SI engine: Warm operating conditions

Development in surface modifications has shown promising outcomes in improving the tribological performance of contacts in hydrodynamic, mixed, and boundary lubrications. Piston ring–liner (PRL) interaction is one type of such contact. Under dynamic loading and extreme operating conditions, PRL conjunction accounts for a substantial portion of the total parasitic losses in IC engines. In this work the mixed lubrication model and realistic oil rheology are considered in order to evaluate and optimize the tribo-characteristics of partially textured barrel-shaped piston ring operating under real engine conditions. Surface texture patterns with varying shapes and orientations are considered and individually optimized to minimize energy loss. Thereafter, the performances of optimized texture patterns are compared. Optimized geometrical parameters for different rings with varying degrees of conformity with cylinder liner are also evaluated. Grooves normal to the sliding direction were found to be the top performer in the hydrodynamic regime, whereas micro-dimples perform better at piston reversals. Thus, micro-dimples resulting from the intersection of orthogonal grooves are also studied. Results show encouraging improvements in frictional behavior.