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Viewing 1 to 30 of 1335
2017-10-08
Technical Paper
2017-01-2421
Dongkang Cheng, Xiaori Liu
Abstract With the enhancement of power density, the thermal load of internal combustion engine becomes an increasingly serious problem, the influence of heat load on the frictional power loss of piston ring is more prominent. A mixed lubrication model is established for the piston ring-cylinder liner system of a diesel engine, the influence of temperature change on the frictional power loss of piston ring-cylinder liner system is investigated. The maximum temperature ranges of the first ring, the second ring and the oil ring are 40 degrees Celsius independently, and the maximum temperature range of the cylinder liner is 20% of its temperature. The results show that: The temperature of cylinder liner has obviously influence on the oil film temperature, while the temperature of piston rings has little influence.
2017-09-04
Technical Paper
2017-24-0060
Nicolo Cavina, Nahuel Rojo, Lorella Ceschini, Eleonora Balducci, Luca Poggio, Lucio Calogero, Ruggero Cevolani
Abstract The recent search for extremely efficient spark-ignition engines has implied a great increase of in-cylinder pressure and temperature levels, and knocking combustion mode has become one of the most relevant limiting factors. This paper reports the main results of a specific project carried out as part of a wider research activity, aimed at modelling and real-time controlling knock-induced damage on aluminum forged pistons. The paper shows how the main damage mechanisms (erosion, plastic deformation, surface roughness, hardness reduction) have been identified and isolated, and how the corresponding symptoms may be measured and quantified. The second part of the work then concentrates on understanding how knocking combustion characteristics affect the level of induced damage, and which parameters are mainly responsible for piston failure.
2017-09-04
Technical Paper
2017-24-0167
Enrico Mattarelli, Carlo Rinaldini, Tommaso Savioli, Giuseppe Cantore, Alok Warey, Michael Potter, Venkatesh Gopalakrishnan, Sandro Balestrino
Abstract This work reports a CFD study on a 2-stroke (2-S) opposed piston high speed direct injection (HSDI) Diesel engine. The engine main features (bore, stroke, port timings, et cetera) are defined in a previous stage of the project, while the current analysis is focused on the assembly made up of scavenge ports, manifold and cylinder. The first step of the study consists in the construction of a parametric mesh on a simplified geometry. Two geometric parameters and three different operating conditions are considered. A CFD-3D simulation by using a customized version of the KIVA-4 code is performed on a set of 243 different cases, sweeping all the most interesting combinations of geometric parameters and operating conditions. The post-processing of this huge amount of data allow us to define the most effective geometric configuration, named baseline.
2017-09-04
Journal Article
2017-24-0021
Sabino Caputo, Federico Millo, Giancarlo Cifali, Francesco Concetto Pesce
Abstract One of the key technologies for the improvement of the diesel engine thermal efficiency is the reduction of the engine heat transfer through the thermal insulation of the combustion chamber. This paper presents a numerical investigation on the effects of the combustion chamber insulation on the heat transfer, thermal efficiency and exhaust temperatures of a 1.6 l passenger car, turbo-charged diesel engine. First, the complete insulation of the engine components, like pistons, liner, firedeck and valves, has been simulated. This analysis has showed that the piston is the component with the greatest potential for the in-cylinder heat transfer reduction and for Brake Specific Fuel Consumption (BSFC) reduction, followed by firedeck, liner and valves. Afterwards, the study has been focused on the impact of different piston Thermal Barrier Coatings (TBCs) on heat transfer, performance and wall temperatures.
2017-09-04
Journal Article
2017-24-0157
Wolfgang Gross, Ahmad Rabanizada, Konstantin Markstädter, Harald Stoffels, Michael Bargende, Adrian Rienäcker
Abstract High combustion pressure in combination with high pressure gradient, as they e.g. can be evoked by high efficient combustion systems and e.g. by alternative fuels, acts as broadband excitation force which stimulates natural vibrations of piston, connecting rod and crankshaft during engine operation. Starting from the combustion chamber the assembly of piston, connecting rod and crankshaft and the main bearings represent the system of internal vibration transfer. To generate exact input and validation values for simulation models of structural dynamic and elasto-hydrodynamic coupled multi-body systems, experimental investigations are done. These are carried out on a 1.5-l inline four cylinder Euro 6 Diesel engine. The modal behaviour of the system was examined in detail in simulation and test as a basis for the investigations. In an anechoic test bench airborne and structure-borne noises and combustion pressure are measured to identify the engine´s vibrational behaviour.
2017-07-10
Technical Paper
2017-28-1954
Premkumarr Santhanamm, K. Sreejith, Avinash Anandan
A local and global environmental concern regarding automotive emissions has led to optimize the design and development of Power train systems for IC engines. Blow-by and Engine oil consumption is an important source of hydrocarbon and particulate emissions in modern IC engines. Great efforts have been made by automotive manufacturers to minimize the impact of oil consumption and blow-by on in-cylinder engine emissions. This paper describes a case study of how simulation played a supportive role in improving piston ringpak assembly. The engine taken up for study is a six cylinder, turbocharged, water cooled diesel engine with a peak firing pressure of 140 bar and developing a power output of 227 KW at 1500 rpm. This paper reveals the influence of stepped land, top groove angle, ring face profile, twist features with regard to tweaking of Blow-by & LOC. Relevant design inputs of engine parameters were provided by the customer to firm up the boundary conditions.
2017-07-10
Technical Paper
2017-28-1977
M Malathi, J Herbert Mabel, R. Rajendran, N Gowrishankar
Abstract Piston rings are used to seal the cavity formed between the piston and the cylinder in order to allow the engine to operate efficiently. The piston rings wear out due to constant rubbing action with cylinder wall and also have to withstand high temperature. This has lead to the development of new piston ring coatings with good wear properties under increasingly challenging running conditions. To improve the wear resistance of the piston rings several coating techniques are employed. One such technique is Ni-P composite coating which is widely used in the automotive industry. Reinforcement of ceramic particles enhances the tribological and mechanical properties of the coating. The base material of the piston ring used in this study is hardened carbon steel. The main objective is to develop an optimum Ni-P composite coating on piston ring to improve wear and friction resistance.
2017-07-10
Technical Paper
2017-28-1981
Sakthinathan Ganapathy, Anand Kumar Appancheal, Raja Velusamy
Abstract Heat energy produced in the combustion chamber of an IC engine cannot be completely converted into useful work due to heat transfer losses. This leads to a fall in the performance of the engine. To overcome this, pistons have been coated with different materials like molybdenum disulphide, chromium nitrides and other materials. These thermal barrier coatings have improved the performance of the engine by preventing heat loss. In this experiment, the performance and emission characteristics of a tungsten carbide coated piston was investigated. WC was coated on the piston surface by EB-PVD Process. The WC coated piston was tested in an MK20 engine using an eddy current dynamometer. The performance of uncoated and WC coated pistons were compared and analyzed. An increase in combustion chamber temperature was obtained while using WC coated piston, which was observed by increased exhaust gas temperature.
2017-03-28
Technical Paper
2017-01-0464
Guang Wang, Xueyuan Nie, Jimi Tjong
Abstract Friction between the piston and cylinder accounts for large amount of the friction losses in an internal combustion (IC) engine. Therefore, any effort to minimize such a friction will also result in higher efficiency, lower fuel consumption and reduced emissions. Plasma electrolytic oxidation (PEO) coating is considered as a hard ceramic coating which can provide a dimpled surface for oil retention to bear the wear and reduce the friction from sliding piston rings. In this work, a high speed pin-on-disc tribometer was used to generate the boundary, mixed and hydrodynamic lubrication regimes. Five different lubricating oils and two different loads were applied to do the tribotests and the COFs of a PEO coating were studied. The results show that the PEO coating indeed had a lower COF in a lower viscosity lubricating oil, and a smaller load was beneficial to form the mixed and hydrodynamic lubricating regimes earlier.
2017-03-28
Technical Paper
2017-01-1042
Eric J. Passow, Paras Sethi, Max Maschewske, Jason Bieneman, Kimm Karrip, Paul Truckel
Abstract Current market demands in conjunction with increasingly stringent emission legislation have vehicle manufactures striving to improve fuel economy and reduce CO2 emissions. One way to meet these demands is through engine downsizing. Engine downsizing allows for reduced pumping and frictional losses. To maintain acceptable drivability and further increase efficiency, power density increase through the addition of boosting is employed. Furthermore, efficiencies have been realized through the use of high gear count transmissions, providing an opportunity for manufactures to effectively down speed the engine whilst still achieving the desired drivability characteristics. As a result of these efficiency improvements, gasoline turbo charged direct injected (GTDI) engines are developed for and tend to operate in low engine speed, high torque conditions .
2017-03-28
Technical Paper
2017-01-1026
Richard Morton, Romain Riviere, Stephen Geyer
Abstract A study of the crank and gear-train dynamics of a two-stroke opposed piston diesel engine design uncovered a disconnect between the thermodynamic process and its conversion to mechanical work. The classic two-stroke opposed piston design phases the intake piston to lag the exhaust piston in order to achieve favorable gas exchange, overcoming the disadvantage of piston-controlled ports. One result of this is that significantly more of the engine torque is delivered by the leading crank than from the trailing one. This paper will examine why this torque difference occurs showing that it is not simply a proportioning of the available thermodynamic work but a result of a fundamental mechanical loss mechanism that limits the achievable brake efficiency of this engine architecture. This analysis will provide a basis for developing effective design solutions to overcome the mechanical loss by providing an understanding of this loss mechanism.
2017-03-28
Technical Paper
2017-01-0250
Jizhou Zhang, Jianhua Zhou, Mian LI, Min Xu
Abstract Manufacturing of the internal combustion engines (ICEs) has very critical requirements on the precision and tolerance of engine parts in order to guarantee the engine performance. As a typical complex nonlinear system, small changes in dimensions of ICE components may have great impact on the performance and cost of the manufacturing of ICES. In this regard, it is still necessary to discuss the optimization of the tolerance and manufacturing precision of the critical components of ICEs even though the tolerance optimization in general has been reported in the literature. A systematic process for determining optimal tolerances will overcome the disadvantages of the traditional experience-based tolerance design and therefore improve the system performance.
2017-03-28
Technical Paper
2017-01-0457
Kenji Matsumoto, Hideharu Koga
Abstract Piston ring wear in gasoline engine induces deterioration of emissions performance due to leakage of blow-by gas, instability of idling caused by reduced compression in combustion chamber, and to generate early degeneration of engine oil. We examined anti-wear performance of DLC coating on piston ring, which had been recently reported as an effective method for improving the abrasion resistance. As a result, wear rate remained low under the condition of DLC existence on sliding surface, but once DLC was worn out completely, wear of the piston ring was accelerated and its life became shorter than piston ring without DLC. In this research, we designed reciprocating test apparatus that operates at much higher velocity range, and characterized the frictional materials of the piston ring and sleeve and the DLC as a protective film, a vapor phase epitaxy (VPE) was actively used as a means to form certain level of convex and concave shape on its surface.
2017-03-28
Journal Article
2017-01-0625
Yen-Chung Liu, Brian Sangeorzan, Alex Alkidas
Abstract The purpose of this research was to measure and correlate the area-average heat transfer coefficients for free, circular upward-impinging oil-jets onto two automotive pistons having different undercrown shapes and different diameters. For the piston heat transfer studies, two empirical area-average Nusselt number correlations were developed. One was based on the whole piston undercrown surface area with the Nusselt number based on the nozzle diameter, and the other was based on the oil-jet impingement area with the Nusselt number based on the oil-jet effective impingement diameter. The correlations can predict the 95% and 94% of the experimental measurements within 30% error, respectively. The first correlation is simpler to use and can be employed for cases in which the oil jet wets the whole piston undercrown. The latter may be more useful for larger pistons or higher Prandtl number conditions in which the oil jet wets only a portion of the undercrown.
2017-03-28
Journal Article
2017-01-1044
Chao Cheng, Akintomide Akinola
Improving engine efficiency and reducing the total cost of ownership demands engine friction loss reduction through optimal design, especially for large bore application considering the amount of fuel the engine consumes during its service life. Power cylinder is a big source for engine friction and piston accounts for about 25% to 47% of the power cylinder friction [1]. Thus the piston design needs to be optimized to minimize friction; and at the same time, not sacrificing the durability. This work focuses on piston friction reduction by utilizing shorter compression height piston for large bore engine application through analytical simulation study. From the simulation study, 12.5% friction reduction has been achieved in the piston skirt to liner interface for the shorter piston with longer connecting-rod compared to the baseline design.
2017-01-10
Journal Article
2017-26-0056
Suramya Naik, David Johnson, Laurence Fromm, John Koszewnik, Fabien Redon, Gerhard Regner, Neerav Abani
Abstract The government of India has decided to implement Bharat Stage VI (BS-VI) emissions standards from April 2020. This requires OEMs to equip their diesel engines with costly after-treatment, EGR systems and higher rail pressure fuel systems. By one estimate, BS-VI engines are expected to be 15 to 20% more expensive than BS-IV engines, while also suffering with 2 to 3 % lower fuel economy. OEMs are looking for solutions to meet the BS-VI emissions standards while still keeping the upfront and operating costs low enough for their products to attract customers; however traditional engine technologies seem to have exhausted the possibilities. Fuel economy improvement technologies applied to traditional 4-stroke engines bring small benefits with large cost penalties. One promising solution to meet both current, and future, emissions standards with much improved fuel economy at lower cost is the Opposed Piston (OP) engine.
2016-11-08
Technical Paper
2016-32-0046
Stephan Schneider, Marco Chiodi, Horst Friedrich, Michael Bargende
Abstract The proposed paper deals with the development process and initial measurement results of an opposed-piston combustion engine for application in a Free-Piston Linear Generator (FPLG). The FPLG, which is being developed at the German Aerospace Center (DLR), is an innovative internal combustion engine for a fuel based electrical power supply. With its arrangement, the pistons freely oscillate between the compression chamber of the combustion unit and a gas spring with no mechanical coupling like a crank shaft. Linear alternators convert the kinetic energy of the moving pistons into electric energy. The virtual development of the novel combustion system is divided into two stages: On the one hand, the combustion system including e.g. a cylinder liner, pistons, cooling and lubrication concepts has to be developed.
2016-11-08
Journal Article
2016-32-0043
Bernhard J. Graf, Christian Hubmann, Markus Resch, Mehdi Mehrgou
Abstract Beside hard facts as performance, emissions and fuel consumption especially the brand specific attributes such as styling and sound are very emotional, unique selling prepositions. To develop these emotional characters, within the given boundary conditions of the future pass-by regulation, it is necessary to define them at the very beginning of the project and to follow a consequent development process. The following paper shows examples of motorcycle NVH development work on noise cleaning and sound engineering using a hybrid development process combining front loading, simulation and testing. One of the discussed solutions is the investigation of a piston pin offset in combination with a crankshaft offset for the reduction of friction. The optimization of piston slap noise as a result of the piston secondary motion was performed by simulation. As another example a simulation based development was performed for the exhaust system layout.
2016-10-17
Technical Paper
2016-01-2336
Ken Naitoh, Soichi Ohara, Yuichi Onuma, Kentaro Kojima, Kenya Hasegawa, Tomoya Shirai
Abstract A single-point autoignition gasoline engine (Fugine) proposed by us previously has a strongly asymmetric double piston unit without poppet valves, in which pulsed multi-jets injected from eight suction nozzles collide around the combustion chamber center. Combustion experiments conducted on this engine at a low operating speed of 2000 rpm using gasoline as the test fuel under lean burn conditions showed both high thermal efficiency comparable to that of diesel engines and silent combustion comparable to that of conventional spark-ignition gasoline engines. This gasoline engine was tested with a weak level of point compression generated by negative pressure of about 0.04 MPa and also at an additional mechanical homogeneous compression ratio of about 8:1 without throttle valves. After single-point autoignition, turbulent flame propagation may occur at the later stage of heat release.
2016-10-03
Journal Article
2016-01-9044
Eric Gingrich, Daniel Janecek, Jaal Ghandhi
Abstract An experimental investigation was conducted to explore the impact in-cylinder pressure oscillations have on piston heat transfer. Two fast-response surface thermocouples embedded in the piston top measured transient temperature and a commercial wireless telemetry system was used to transmit thermocouple signals from the moving piston. Measurements were made in a light-duty single-cylinder research engine operated under low temperature combustion regimes including Homogeneous Charge Compression Ignition (HCCI) and Reactivity Controlled Compression Ignition (RCCI) and Conventional Diesel (CDC). The HCCI data showed a correlated trend of higher heat transfer with increased pressure oscillation strength, while the RCCI and CDC data did not. An extensive HCCI data set was acquired. The heat transfer rate - when corrected for differences in cylinder pressure and gas temperature - was found to positively correlate with increased pressure oscillations.
2016-09-27
Technical Paper
2016-01-8091
Shuanlu Zhang, ZhenFeng Zhao, Changlu Zhao, Fujun Zhang, Yuhang Liu
Abstract A new method for driving the hydraulic free piston engine is proposed. This method achieves the compression stroke automatically rather than special recovery system. Principle of hydraulic differential drive free-piston engine is analyzed and the control strategy of this novel hydraulic driving engine is also introduced. Then energy balance method is used to design the main parameters of the novel engine. High pressure and secondary high pressure of the hydraulic system are constrained by the combustion parameters and therefore parameters are analyzed. In order to verify the effectiveness of energy balance method, the mathematical model is established based on the piston force analysis and engine working principle. The transient results of dynamics are obtained through simulation. In addition, the effectiveness of the simulation is proofed by dimensionless analysis. It indicates that energy balance method realizes the basic performance of hydraulic free piston engine.
2016-09-27
Journal Article
2016-01-8100
Jordan Kelleher, Nikhil Ajotikar
Abstract Piston cooling nozzles/jets play several crucial roles in the power cylinder of an internal combustion engine. Primarily, they help with the thermal management of the piston and provide lubrication to the cylinder liner and the piston’s wrist pin. In order to evaluate the oil jet characteristics from various piston cooling nozzle (PCN) designs, a quantitative and objective process was developed. The PCN characterization began with a computational fluid dynamics (CFD) turbulent model to analyze the mean oil velocity and flow distribution at the nozzle exit/tip. Subsequently, the PCN was tested on a rig for a given oil temperature and pressure. A high-speed camera captured images at 2500 frames per second to observe the evolution of the oil stream as a function of distance from the nozzle exit. An algorithm comprised of standard digital image processing techniques was created to calculate the oil jet width and density.
2016-09-27
Journal Article
2016-01-8066
Marco Maurizi, Daniel Hrdina
Abstract Total cost of ownership is requiring further improvements to piston friction reduction as well as additional gains in thermal efficiency. A piston compression height reduction in combination with carbon based piston pin coatings is enabling advancements in both demands. MAHLE implemented a new innovative metal joining technology by using laser welding to generate a cooling gallery. The MonoLite concept offers design flexibility which cannot be matched by any other welding process. Especially an optimum design and position of the cooling gallery as well as durability for very high peak cylinder pressures can be matched. This is particularly advantageous for complex combustion bowl geometries that are needed in modern diesel engines to meet fuel economy and emission requirements. The MonoLite steel piston technology offers a superior compression height reduction potential compared to typical friction welded designs.
2016-06-15
Technical Paper
2016-01-1775
Thomas Resch, Oliver Knaus, Siegmund Thomann, Stephan Brandl
Abstract Modern powertrain noise investigation in the development process and during trouble shooting is a combination of experiment and simulation. In simulation in recent years main focus was set on model completeness, consideration of all excitation mechanisms and efficient and stabile numerical algorithms. By that the total response of the virtual powertrain is already comparable to the overall noise level of the real powertrain. Actual challenge is to trace back the overall response to its main excitation and noise generating mechanism as well as to their main driving parameters to support the engineer not only in reaching absolute values, but also to derive the root cause of a response or potential problem and to get hints on how to improve the specific behavior. Approaches by parameter sensitivity studies are time consuming and not unambiguous.
2016-06-15
Journal Article
2016-01-1855
Alastair Jay, Thomas Deighan, Nozomu Kato, Kiyofumi Sato
Abstract Requirements for reducing powertrain NVH drives the selection of low piston skirt to liner clearances contradicting the requirement to maintain larger skirt clearances for minimizing engine friction. Whilst this clearance trade-off between low friction and low NVH is fundamental, piston design features have a significant effect on where the trade-off curve sits on the friction/NVH map. Design features can therefore be viewed not by either friction or NVH improvement measures but a shift in the friction-NVH trade off curve. Specifically, some piston design features which may be targeted at reducing friction can be viewed as either a friction benefit for similar NVH or an NVH improvement for similar friction levels. The ability to realistically quantify the effect of the design changes on NVH is therefore critical to determining what design changes to recommend, the direction of the piston design being highly sensitive to the process by which the impact on NVH is assessed.
2016-04-05
Technical Paper
2016-01-0642
Eric Zanghi, Tian Tian
Understanding oil transport mechanisms is critical to developing better tools for oil consumption and piston skirt lubrication [1]. Our existing Two-Dimensional Laser Induced Fluorescence (2DLIF) system with an acquisition rate of 1 frame every one or two cycles was proven to be effective to display oil accumulation patterns and their evolution over many cycles in the piston ring pack system [2,3,4]. Yet, the existing system is unable to resolve instantaneous oil flow patterns in the piston-liner interface. In this work, a high-speed LIF system was developed. After a number of iterations the finalized high speed LIF system includes a 23 W, 100 kHz, 532 nm laser and a high speed camera capable of 100,000 FPS at 384 × 264 pixel resolution. After each component was selected, optimization of the quality of images taken from the system began.
2016-04-05
Technical Paper
2016-01-0546
Henry McCabe, William F. Northrop, James Van de Ven
Abstract The impact of compression ratio on engine efficiency is well known. A plethora of mechanical concepts have been proposed for altering engine compression ratio in real time. Some of these, like free-piston configurations or complex crank-slider mechanisms have the added ability to alter piston trajectory along with compression ratio. This secondary modality raises the question: Is there a more optimal piston position versus crank-angle profile for spark-ignition (SI) engines than the near-sinusoidal motion produced by a traditional four-bar crank-slider mechanism? Very little published literature directly addresses this question. This work presents the results of a quasi-dimensional SI engine model using piston trajectory as an input. Specific trajectory traits including increased dwell at top dead center and asymmetric compression and expansion strokes were swept.
2016-04-05
Technical Paper
2016-01-1046
Pasquale Pio Totaro, Zachary Westerfield, Tian Tian
Abstract The piston’s skirt shape is a key design parameter since it critically influences lateral displacement, tilting movement, oil transport and consequently engine performances. This study proposes an alternative skirt profile that aims to reduce frictional losses between the piston and cylinder liner. Qualitatively, the proposed profile, aims to reduce solid-to-solid contact friction by increasing the total hydrodynamic forces generated on the skirt to balance side forces, and to prevent both sides of the skirt to interact with the liner simultaneously. The new skirt’s profile has been first studied and optimized using a piston secondary motion model and then prototyped and tested on a floating liner test bench, showing a 12% average reduction in total piston FMEP.
2016-04-05
Journal Article
2016-01-1048
Zachary Westerfield, Yang Liu, Dallwoo Kim, Tian Tian
Abstract The oil control ring (OCR) controls the supply of lubricating oil to the top two rings of the piston ring pack and has a significant contribution to friction of the system. This study investigates the two most prevalent types of OCR in the automotive market: the twin land oil control ring (TLOCR) and three piece oil control ring (TPOCR). First, the basis for TLOCR friction on varying liner roughness is established. Then the effect of changing the land width and spring tension on different liner surfaces for the TLOCR is investigated, and distinct trends are identified. A comparison is then done between the TLOCR and TPOCR on different liner surfaces. Results showed the TPOCR displayed different patterns of friction compared the TLOCR in certain cases.
2016-04-05
Technical Paper
2016-01-1047
Kohei Nakashima, Hiroyuki Nagakura, Takashi Ooguro, Masago Yamamoto
Abstract To accurately measure piston ring radial-force, we constructed an instrument arraying 12 measuring assemblies, spaced 30º apart around the ring circumference, each comprising a roller, a slider, a load cell in a holder, and a micrometer head. Using this measuring device, we investigated the radial-force distribution in several compression rings with various ovalities. For each ring, we first measured the radial force at 30º intervals around the ring circumference, avoiding the ring gap, and then we displaced the ring 15º in the circumferential direction, and set a custom jig between the ring gap and the measuring assembly. Thus we were able to measure the radial-force at 15º intervals around the entire circumference, including the ring gap position.
Viewing 1 to 30 of 1335

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