Internal Combustion Engine Piston Research Articles

Effects of the Piston Skirt’s Surface Structure on Coating Quality and Friction Functions

It is necessary to take effective ways to reduce friction and wear grading of a friction pair for the purpose of improving the thermal efficiency and operating reliance of the internal combustion engine. As an effective way, coordinated multi-scaling structure optimization has gained more and more attention, however, its effect on coating adhesion strength remains unclear, and there is less systematic research on its interactive role in friction properties. The paper takes advantage of the stretching test and dynamic simulation calculation to study the influence of piston skirt waviness on coating adhesion as well as profile, waviness, and roughness on friction and wear performance. The research results show that coating adhesion strength will increase first and then decrease in the conditions of enlarging waviness depth, width, and roughness; in addition, surface roughness could generate a bigger effect on coating adhesion than waviness shape. Increasing the waviness width also reduces friction losses and wear in the piston skirt. When the waviness width increases from 0.25 mm to 0.40 mm, the friction losses of the piston skirt decrease by 27%, and the cumulative wear load on the skirt is reduced by 26%. However, under conditions of limited lubrication, smaller waviness widths are more effective in reducing wear. Additionally, increased roughness has a negative impact on the friction and wear characteristics of the piston skirt. This study provides valuable guidance for optimizing designs aimed at reducing friction and wear in internal combustion engine pistons and other mechanical components subject to friction and wear.

Thermo-structural Comparative Analysis of Internal Combustion Engine Piston by Finite Element Methods

Thermo-structural Comparative Analysis of Internal Combustion Engine Piston by Finite Element Methods

The Hydrogen Vehicle in the Context of the Sustainable Development of the Green Road Transport System

Abstract The scientific work presents concrete research carried out by the authors to implement some concepts of technical and managerial nature, so that those interested in this field can get acquainted with a certain way of exposing the problems concerning the hydrogen-powered vehicle, in the context of the sustainable development of the ecological road transport system. At the moment, the car whose energy for propulsion is generated by means of hydrogen or hydrogen fuel cells does not enjoy a high popularity among users, due to the very high purchase price (where we have high technology, we also have a price to match - a fuel cell is more expensive than an electric battery), the reluctance of the population to use this type of fuel, defined by the danger of explosions and fires generated by hydrogen, and the lack of hydrogen refueling stations in Romania and in some European countries. The use of alternative fuels in internal combustion piston engines has the advantage of significantly reducing pollution due to combustion products. With regard to the direct use of hydrogen as a fuel in internal combustion piston engines, we can say that it has proved its inefficiency, because the hydrogen injected or sucked directly into the engine cylinders is unstable, produces uncontrolled burns and detonations, and in the liquid state it is very difficult to store, it requires special transport methods, hydrogen tanks must be armored with Kevlar because hydrogen in the event of a car accident can explode. For example, if we use it as a fuel in a diesel engine, hydrogen may not ignite itself because the self-ignition temperature in the cylinders of compression-ignition engines is high (600°C). However, at a normal stoichiometric ratio, hydrogen has a high flame rate, much higher than gasoline. This creates a thermodynamic cycle of the thermal engine almost perfectly, but ideally, let us not forget that in poor mixtures of air-hydrogen the flame propagation speed is considerably reduced. The compression ratio of the engine is of utmost importance because it is finally defining the thermal efficiency of the engine. In the following, we present a technical and managerial study with engineering nuances, through which readers can look and understand the stage of development, place and role of the vehicle propelled by hydrogen fuel cells. Finally, the conclusions and further directions of research and development in the field addressed are presented.

A study on the influence of utilizing hydrogen at fuelling spark ignition engines

Abstract In the last 30 years, remarkable progress has been made in reducing pollutant emissions and fuel consumption in conventional internal combustion engines. Active and passive methods of reducing exhaust emissions have caused them to decrease significantly over the level of the 1980s. However, the problems of air pollution and the greenhouse effect are far from being solved. International organizations and institutions are pushing for measures to reduce emissions, especially the implementation of “zero-emission” (ZEV) vehicles. Due to its excellent combustion properties and the very low pollutant emissions resulting from its combustion, hydrogen is seen as an alternative fuel of the future. Hydrogen can be used as a fuel in two ways: in internal combustion piston engines or in fuel cells. Research into the use of hydrogen as a fuel for spark ignition engines is divided into two directions: additive fuel or a total gasoline substitution with hydrogen. Compared to the gasoline-powered engine, the fully hydrogen-powered engine runs more economically at low loads but it can create a decrease of performance at high loads due to the high volumes of space needed in the combustion chamber. Because of the very low density, high volumes of hydrogen are difficult to storage, requiring also high pressure, so running only on hydrogen wouldn’t be practical. Combining the advantages of the two fuels came the use of gasoline with addition of hydrogen. An important aspect is that emissions are significantly reduced due to the very good combustion properties of hydrogen and the high diffusivity that helps to form a homogeneous mixture. This paper presents aspects of fuelling a spark ignition engine with gasoline and hydrogen. The influence of hydrogen on the cylinder mixture, on the energy and emissions of the engine is analysed. We will focus on: engine power, fuel consumption, the level of pollutant emissions and greenhouse gases, at the studied regimes.

Combustion Test for the Smallest Reciprocating Piston Internal Combustion Engine with HCCI on the Millimeter Scale

Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to structural simplification of the reciprocating piston internal combustion engines under a micro space constraint but has not been adequately verified at the millimeter scale. The study used a millimeter-scale HCCI reciprocating piston internal combustion engine fueled by a mixture of kerosene, ether, castor oil, and isopropyl nitrate for combustion investigation. The test engine with a displacement of 0.547 cc is the smallest reciprocating piston internal combustion engine known to have undergone in-cylinder combustion diagnosis. It is observed that the HCCI combustion mode at the millimeter scale can realize stable combustion with excellent cooperation for the thermodynamic cycle under appropriate structural and operating conditions, which is essentially not inferior to those in conventional-sized reciprocating piston internal combustion engines. This finding helps the next step of scaling down reciprocating piston internal combustion engines.

Novel Approach to Analyzing Friction Losses by Modeling the Microflow of Lubricating Oil between the Piston Rings and Cylinder in Internal Combustion Engines

This work focuses on the evolution of lubrication wedge shaping in internal combustion piston engines, taking into account liquid microflows on curved surfaces and coating microgeometries. It introduces a new approach to the analysis of friction losses by simulating the microflow of lubricating oil between the surfaces of piston rings cooperating with the cylinder surface. The models used take into account three types of microgeometry and material expansion. Key results indicate that microirregularities with a stereometry of 0.1–0.2 µm significantly influence the distribution of oil film thickness in the phase of maximum working pressure, which is critical for the functioning of the seal ring. The innovation of the work consists of demonstrating that, despite small changes in the friction force and power in the piston rings, changes in the minimum values of the oil film thickness are significant. The work highlights the failure to take into account microgeometry parameters in friction models, which leads to significant errors in the simulation results, especially in terms of oil film continuity and the contribution of mixed friction. The simulations also indicate that advanced geometric models with high mesh resolution are necessary only for the assessment of changes in oil film thickness during the highest pressure increase in the combustion chamber and taking into account various mixed friction conditions. The results suggest significant progress in engine design and performance, confirming the importance of advanced fluid and mixed friction models in piston engine lubrication research.

FEM Analysis And Design Optimization Of The Piston

The workings of an engine rely on the piston rod and/or connecting rod to transmit the force of the expanding gas in the cylinder to the crankshaft. Because of its critical role in engines, the piston is subject to inertial stresses and cyclic gas pressure, which may lead to fatigue damage in the form of side wear, fractures in the piston head or crown, and other issues. According to the research, the top of the piston experiences the highest level of stress, which is a major contributor to fatigue failure. This study uses finite element analysis to illustrate the stress distribution on an internal combustion engine's piston. It is the CAD and CAE programs that carry out the FEA. Examining and analyzing the distribution of thermal and mechanical stresses on the piston under real-world engine conditions during combustion is the primary focus. Predicting the component's critical area and greater stress using finite element analysis is also detailed in the paper. Created a structural model of a piston using CATIA software. We ran simulations and stress analyses with the help of ANSYS V14.5.

The efficiency of thermal protection of ICE pistons with the micro-arc oxidation

BACKGROUND: In order to protect pistons of internal combustion engines (ICE) from burnout and increase their durability, it is reasonable to use ceramic coatings formed on the piston head with micro-arc oxidation (MAO). Many scientific papers have been devoted to the study of the efficiency of these coatings. However, most of these studies were carried out at laboratory facilities simulating the engine operation, generally, not taking into account the real thermophysical parameters of the MAO coating. Therefore, the thermal protection efficiency of these coatings is difficult to assess. AIM: Study of efficiency of the thermal protection of pistons using a ceramic coating formed by micro-arc oxidation on the piston head with numerical simulation. METHODS: The study was conducted in the SolidWorks Simulation software. Two piston aluminum alloys were used as the piston material: AK12d (with a silicon content of 12%) and AK4-1 (with a silicon content of 0.35%). Temperature loads corresponding to the operation of a real engine were applied to the surfaces of the model piston. At the first stage of the study, the thermal state of pistons made of different uncoated alloys was simulated. At the second and third stages of the study, the effect of the coating thickness on the piston thermal state was simulated. The piston material of the second study stage was the AK4-1 alloy. The piston material of the third study stage was the AK12d alloy. Ceramics, which properties correspond to the coatings properties formed with the micro-arc oxidation method on these alloys, were used as the coating material. The coating thickness varied in the range from 50 to 350 µm in increments of 100 µm. The probing method was used to determine the temperature in various areas of the piston, such as at the piston head surface at the MAO coating and under it, in the area of piston grooves, at a piston skirt and the piston head from the side of a crankcase. RESULTS: With the simulation, it was found that: The micro-arc coating of the piston head reduces the thermal tension of the piston regardless of the aluminum alloy chemical composition. The efficiency of the piston’s thermal protection increases with an increase in the ceramic coating thickness and a decrease in its thermal conductivity coefficient. The greatest heat-protecting effect is achieved by the piston made of the AK12d eutectic alloy. CONCLUSIONS: It is found that the MAO coating at the piston head is an effective way to reduce the thermal tension of the ICE pistons. Increasing the ceramic coating thickness and a decrease in its thermal conductivity coefficient increases the efficiency of the pistons thermal protection. Reducing the thermal conductivity of the MAO coating and increasing the MAO coating thickness increases the temperature on the coating surface.

Enhancing Fuel Efficiency of Internal Combustion Engine through the Application of Nanostructured Aluminium Alloy in Pistons

‌The automobile and motorsport industires are under immense pressure due to emission laws to reduce fuel consumption and alleviate the effects of global warming. This experimental study compared the performance of internal combustion engine pistons made of a newly developed nanostructured aluminium alloy (RSA-612) and conventional aluminium alloy 2618. The new alloy is expected to reduce piston mass which will reduce piston assembly frictional losses and lead to reduced fuel consumption. The new alloy has lower density and higher strength at elevated temperatures than conventional aluminum alloys, and the final machined piston was 13.5% lighter than the original piston. The limited engine testing carried out in this study showed that the new piston produced enhanced performance in certain engine operating conditions, whilst performing similarly or slightly worse in others. Further testing with the new piston is advised to assess engine performance across wider engine running envelope.

Improving the physical, mechanical and operational characteristics of cast internal combustion engine pistons made of aluminum alloy using secondary charge

The article is devoted to improving the physical, mechanical and operational characteristics of cast internal combustion engine pistons made of aluminum alloy using secondary charge. The advantage of the proposed approach is that these parts are manufactured from any aluminum alloy using the remelting of failed internal combustion engine parts of the same name. The paper shows that while using a secondary charge in the form of remelting failed parts of the same name, the quality of cast products not only does not deteriorate, but, on the contrary, their physical and mechanical characteristics even increase. It should be noted that the high density of the alloy obtained from remelting failed pistons and the high degree of its modification confirmed the authors’ assumption that in this case refining and modification operations can be avoided. The presented approach using the remelting of failed parts makes it possible not only to save fresh charge materials, but also to preserve the chemical composition of the primary parts, and, consequently, the level of their physical, mechanical and operational characteristics.

Analysis of scooter engine piston damage

The causes of operational damage to the piston of a single-cylinder two-stroke internal combustion engine (ICE) of a scooter, made of a piston aluminum-silicon alloy by mold casting, were investigated. It was found that the AK21M2.5H2.5 type alloy has a dispersed eutectic structure (α+β-Si) with a small number of primary silicon crystals of a compact shape, the size of which does not exceed 10 μm. The porosity of the cast alloy of the piston is less than the lowest 1st porosity point, as well as the quality structure, could not be the cause of its damage. The average value of the microhardness measured on the surface of the piston head (70 HV0.98) is slightly less than the standardized hardness (90 НВ ÷ 100 НВ) of ingots after mold casting and artificial aging without preliminary hardening, which indirectly indicates overheating of the piston during operation. The detected damage to the outer surface of the piston in the form of deep scratches and worn stripes is not caused by metallurgical or technological factors, but by violations of operating conditions: overheating and lack of lubricant in the contact zone of the piston and cylinder.

Analysis of the effectiveness of using torsional vibration dampers for crankshafts with adaptive characteristics in internal combustion engines

The research aims to determine the effectiveness of torsional dampers with adaptive characteristics for crankshafts of piston internal combustion engines. The paper deals with the pressing issue of designing a torsional vibration damper for crankshafts of internal combustion engines, which can work efficiently in the entire operating range of speed variance. The standard approach to design the damper with constant characteristics implies one resonant operating mode, which in actual practice is not always justified. This fact decreases the operating efficiency, especially for the forced V-type engines. In order to determine the design parameters of dampers with adaptive characteristics, a multi-parameter optimization problem must be solved, which requires experimental validation. The work considers an approximate method, according to which the main parameters of the designed damper for different operating modes are determined. We obtained the general trend of changing the torsional damper characteristics by performing calculations for different engine operating modes. Based on these data, it is possible to determine the operating modes of the control mechanism. Comparing the efficiency of dampers with constant characteristics under the same modes allows validating the results’ adequacy. The scientific novelty lies in the developed method of modes determining torsional vibration damper parameters at changing speed and operating can help design new efficient forced internal combustion engines.

Effect of mao ceramic coating on the stress-strain state of internal combustion engine pistons

Effect of mao ceramic coating on the stress-strain state of internal combustion engine pistons

The concept of the contact angle in the process of oil film formation in internal combustion piston engines

In internal combustion piston engines, the process of oil film formation differs from that in industrial machines. The adhesive strength of the molecules at the interface between the coating of engine parts and the lubricating oil affects the load carrying capacity and the ability to form a lubricated film. The geometry of the lubricating wedge between the surfaces of the piston rings and the cylinder wall is determined by the thickness of the oil film and the amount of oil coverage of the ring. This state is modified by many parameters describing the operation of the engine and the physical and chemical parameters of the coatings of the cooperating pairs. For lubricating molecules reaching energies greater than the energy barrier of adhesion at the boundary, sliding occurs. Therefore, the value of the contact angle of the liquid on the surface of the coating depends on the value of the intermolecular force of attraction. According to the author, there is a strong correlation between the contact angle and the lubrication effect. Research indicates that the potential barrier is a function of the contact angle and the contact angle hysteresis (CAH). The innovation of the work consists in the study of the contact angle and CAH in the conditions of thin layers of lubricating oil in cooperation with hydrophilic and hydrophobic coatings. The thickness of the lubricating film was measured under various speed and load conditions using optical interferometry. The study proves that CAH is a better interface parameter to correlate with the effect of hydrodynamic lubrication.

Analysis of the prospects for hydrogen-fuelled internal combustion engines

Hydrogen, as a zero-emission fuel, makes it possible to build a piston combustion engine that can be qualified as a drive for a "Zero Emission Vehicles", in terms of CO2 emissions. Thus, a hydrogen-powered piston combustion engine may be a future transitional technology for powertrains, especially in trucks and off-road vehicles, competitive with both electric drives and fuel cells. The article presents a multi-directional analysis of the prospects for the development and dissemination of hydrogen-powered internal combustion piston engines in motor vehicles. The current interest of the automotive industry in hydrogen-powered internal combustion engines, current state of their development and the challenges that need to be overcome were presented. Various conditions that will determine their future in Europe were also indicated.

An Overview of the Global Market, Fleet, and Components in the Field of Aviation Gasoline

Aviation gasoline is a fuel for spark-ignition piston internal combustion engines, which are usually used in light aircraft (small aviation and general aviation). This technique is widely used for regional and interregional transportation, for the initial training and retraining of aviation staff, for private use, for agricultural purposes, for the development of aviation sports and tourism, and for combat and rescue operations. This article gives some estimates of the production and consumption of aviation gasoline in the EU, North and South America, Asia–Pacific, Africa, and CIS countries. Export possibilities and the reliance on import within different regions are analyzed. Economic indicators for aviation gasoline are calculated by assessing the share of its production in the GDP and per capita consumption. In the context of the transition to unleaded aviation gasoline, the structure of the piston aviation fleet and its readiness for the transition are considered. The paper also analyzes the following existing components of unleaded aviation gasoline: technical capabilities and promising components.

PROFILING OF THE OUTER SURFACE OF THE PISTON

The piston is one of the main resource-intensive and knowledge-intensive parts of the internal combustion engine. Its design significantly affects almost all indicators of the perfection of the power plant with internal combustion engines as a whole. A correctly designed profile is the main parameter that allows the engine to blow safely during the first starts. The development, production and use of pistons in the primary and secondary markets is impossible without appropriate scientific research that will increase the design and technological capabilities of all interested parties. Pistons for gasoline internal combustion engines of passenger cars will continue to dominate the markets, which is connected with the greening of transport as a whole. This emphasizes the importance of research on the improvement of positive-ignition internal combustion engine pistons. Rational profiling of the outer surface is an important task for improving the design of the piston. The diagram of the design creation technology, which was adopted by JSC "AVTRAMAT" (Kharkiv Plant "Porshen") as the standard of the enterprise, according to which pistons were created, which were then supplied to factories of the engine-building industry and for spare parts, is given. The profiles of the side surfaces of the pistons of automobile internal combustion engines, which were designed and implemented in production, were analyzed. The analysis was carried out for pistons with a diameter of 72 to 100 mm and a height of 45 to 73 mm. It is shown that the given profiles of the side surfaces in these pistons are geometrically similar both along and perpendicular to its axis. It is shown that the geometric shape of the profile can be described by polynomials of the 3rd and 4th degree, which allows for easy further use. This can be used when designing the profiles of future structures. Formulas and an algorithm are given, according to which it is possible to calculate the external profile of pistons of automobile reciprocating internal combustion engines according to 2 parameters - diameter and height.

The use of high-strength cast iron with a ferritic structure for the reciprocating displacement system of the internal combustion engine pistons and the improvement of its operation parameters

A study of compositions of samples of high‑strength cast iron, the use of which is possible in the development of an internal combustion engine with an improved design of a combined reciprocating conversion system, has been carried out. A number of research methods were carried out, including isothermal hardening. The optimal combination of strength and plastic properties have samples from high‑strength cast iron containing, wt.%: 2.9–3.1 C; 3.2–3.5 Si; 0.28–0.31 Mn; 0.7 Cu; 0.35 % Mo and 0.025B. Also, in the course of the study, the possibility was considered and studies were conducted on quenching cast iron in a spray chamber and jet cooling, as an alternative to traditional quenching in molten salts. The data obtained indicate that during jet‑air isothermal quenching, the structure of cast iron is completely and uniformly formed along the cross‑section, while providing a level of tensile strength up to 950 MPa, hardness up to 360–370 NV while maintaining elongation at tension up to 8 %. The use of such a class of cast iron in improved KSPVPP will both increase the life of the internal combustion engine as a whole, and improve its operational characteristics – reduce noise and reduce the weight of the structure.

Thermodynamic analysis and comprehensive system optimization of the near zero emission hybrid power based on SOFC-ICE integrated system fueled with ammonia

The highly efficient heat and mass integrations fueled with ammonia of solid oxide fuel cell and reciprocating piston internal combustion engine are conducted from the viewpoints of characters of restrained / unrestrained chemical reaction and principle of energy cascade utilization. According to previous studies, we classified such integrations into serial and parallel topologies. Based on the detailed and verified models, the power matching limits of serial and parallel integrations are proposed first, showing a narrow scale of power matching of fuel cell and engines, due to the finite engine displacement. Furthermore, based on the design concepts of serial and parallel integrations, the improvement and optimization of combined systems were conducted, which showed that the possibly highest efficiency of serial and parallel systems can reach 70.53% and 68.40%, respectively. Additionally, the exergy analysis of systems could prove that such heat and mass integrations can effectively use remaining heats and fuels, leading to less exergy destructions and optimal designs and operation points achievement, while the maximum exergy destruction occurs at engine. Finally, the environmental analysis results showed that the corrected NO, NO2, N2O and NH3 emissions can reach 0.01 mg/kWh, 5.00 μg/kWh, 29.50 mg/kWh and <5 ppm, achieving near zero emissions.

The Theory of the Surface Wettability Angle in the Formation of an Oil Film in Internal Combustion Piston Engines.

In internal combustion piston engines, the formation of an oil film is completely different from that seen in industrial machines. The molecular adhesion force at the interface between the surface coating of engine parts and the lubricating oil determines the load-carrying capacity and the ability to form a lubricated film. The geometry of the lubricating wedge between the surfaces of the piston rings and the cylinder wall is created by the thickness of the oil film and the height of the ring's coverage with lubricating oil. This condition is affected by many of the parameters that characterize the engine's operation and the physical and chemical parameters of the coatings used for the cooperating pairs. For lubricant particles that reach energies that are higher than the potential energy barrier regarding adhesive attraction at the interface, slippage occurs. Therefore, the value of the contact angle of the liquid on the surface of the coating depends on the value of the intermolecular force of attraction. According to the current author, there is a strong relationship between the contact angle and the lubrication effect. The paper shows that the surface potential energy barrier is a function of the contact angle and contact angle hysteresis (CAH). The innovation of the current work consists in examining the contact angle and CAH under the conditions of thin layers of lubricating oil, in cooperation with hydrophilic and hydrophobic coatings. The thickness of the lubricant film was measured under various speed and load conditions, using optical interferometry. The study shows that CAH is a better interfacial parameter for correlation with the effect of hydrodynamic lubrication. This paper presents the mathematical relationships relating to a piston engine, various coatings, and lubricants.