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Viewing 1 to 30 of 39881
Technical Paper
2014-11-11
Ken Fosaaen
Global concerns over pollution have led to increasingly strict emissions legislation targeting small engines, which currently pollute at a much greater level than modern multi-cylinder automotive engines. Closed-loop control may be required to meet many future legislation requirements; however, such systems can be impractical due to high added component costs. A necessary component for closed-loop engine control is an oxygen sensor. Existing automotive oxygen sensors are too large, require too much power, and far too expensive to be suitable for the vast majority of the global small engine applications; therefore, some manufacturers have developed smaller and/or unheated versions based on their existing sensors to meet this emerging need. The ability to miniaturize resistive based sensors well below that of traditional Nernst (zirconia based) oxygen sensors affords the opportunity to meet future emissions standards with less of an impact on cost. The performance of a novel low-cost, low-power narrow-band oxygen sensor was compared with several automotive as well as newer oxygen sensors developed for the small engine market.
Technical Paper
2014-11-11
Vinoth Balaram Ranganathan, Rajarajan Kesavelu, Adrian Spencer, Andrew Wood
Gasoline Direct Injection (GDI) has great potential to reduce CO2 emissions as compared to the well established Port Fuel Injection (PFI) technology. It is one of the familiar GDI strategies to have more than one injection in a single engine cycle and it is termed as split injection. Understanding the fuel spray characteristics in GDI technology is essential for achieving better combustion process. In this context, A.Wood [1] studied the spray characteristics of a multi-stream, split-type, Continental injector using shadowgraphy and Phase Doppler Anemometry (PDA) measurement techniques on an atmospheric test rig. Atmospheric test rig is not very representative of actual in-cylinder conditions. However, the optimisation of GDI engine requires a thorough understanding of fuel spray characteristics under engine -relevant operating conditions. As an extension of the work done by A.Wood, in the present study, the spray characteristics of a three-hole multi-stream GDI injector from Continental is analysed by spraying the fuel into an optical chamber under conditions closer to in-cylinder pressure and temperature.
Technical Paper
2014-11-11
Ken Naitoh, Tomoaki Kubota, Kan Yamagishi, Yoshiyuki Nojima, Takuma Okamoto
In our previous reports, we found an inexpensive, lightweight, and relatively quiet engine reactor that has the potential to achieve thermal efficiency over 50% for small engines may be achieved with colliding supermulti-jets that create air insulation to encase burned gas around the chamber center, avoiding contact with the chamber walls and piston surfaces. One of interesting features is that, although traditional homogeneous compression due to piston becomes weak at stoichiometric condition, the colliding of pulse jets can maintain high compression ratio for various air-fuel ratios. Here, a small prototype engine having colliding supermulti-jets pulsed and strongly-asymmetric double-piston system is examined by using compuattional experiments. Pulse can be generated by the double piston system of a short stroke of about 40mm. An original governing equation extended from the stochastic Navier-Stokes equation lying between the Boltzmann and Langevin equations is proposed and the numerical methodology based on the multi-level formulation proposed previously by us is included, which can also capture cyclic variations of combustion in traditional direct-injection gasoline engine and transition to turbulence in intake pipes.
Technical Paper
2014-11-11
Ken Naitoh, HIrotaka Sagara, Taro Tamura, Taiki Hashimoto, yoshiyuki Nojima, Masato Tanaka, kentaro kojima, Kenya Hasegawa, Takuya Nakai, Taiki Ikoma, Shouhei Nonaka, Tomoaki Kubota
In our previous reports based on computational experiments and fluid dynamic theory, we proposed a new compressive combustion principle for an inexpensive, lightweight, and relatively quiet engine reactor that has the potential to achieve thermal efficiency over 50% even for small combustion chambers having less than 100 cc. This level of efficiency can be achieved with colliding supermulti-jets that create complete air insulation to encase burned gas around the chamber center. The P-V diagram for this engine concept is between the Otto and Lenoir cycles. We originally developed two small prototype engine systems for gasoline. First one having one rotary valve for pulsating the intake flow and also sixteen nozzles of jets colliding is for examining combustion occurrence. As this prototype has no pistons, the bore size can be varied easily between about 50mm and 15mm. Experimental data basically indicates combustion occurrence. Next, we developed the second one having a strongly-asymmetric double piston system with the supermulti-jets colliding, although there are no poppet valves.
Technical Paper
2014-11-11
Rajarajan Kesavelu, Rajagopalan V R, V Lakshminarasimhan, Pramod S Mehta, S R Chakravarthy
In an era of vigorous engine R&D in automobile industry, there is need to meet stringent fuel economy and emission norms. For this purpose, the understanding of in-cylinder flow processes is critical as they are central to engine combustion and its associated effects. The optical access engines with laser based diagnostics have proved useful for investigating intricacies of in-cylinder motions. Single cylinder engines with smaller bore (< 60 mm) are quite popular on two-wheeler vehicles in Asian countries particularly in India. Though wider optical investigations have been carried out on larger bore engines, not much published works are available on the smaller bore engines close to production series. In this study, an optical engine is developed based on Bowditch design for a mass manufactured 110 cc, 4 stroke, air cooled SI engine used on motorbikes. The over-squared indigenously developed spark-ignited optical engine is designed to have a complete optically-transparent piston crown and a cylinder liner made of quartz.
Technical Paper
2014-11-11
Atsushi Maruyama, Gaku Naoe
For a small general purpose engine, the authors have studied about the mechanical noise originating from combustion, which is called “combustion noise”. The Purpose of this study is to clarify the generating mechanism of combustion noise, and the relation between combustion noise and the components design unique to small general purpose engines. In development of internal-combustion engines, the improvement in fuel economy performance is one of the most important issues. For this purpose, various methods to improve combustion efficiency are suggested. However, most of those methods involve the increase in cylinder pressure or rapid combustion, which causes the increase in combustion noise. Therefore, technological development for reducing the combustion noise is also an issue. Although a number of previous papers about combustion noise focused on the engines used for motorcycle or automobile, few papers focused on small general purpose engines. By contrast, this study focuses on the small general purpose engine.
Technical Paper
2014-11-11
Patrick Pertl, Philipp Zojer, Michael Lang, Oliver Schoegl, Alexander Trattner, Stephan Schmidt, Roland Kirchberger, Nagesh Mavinahally, Vinayaka Mavinahalli
The automotive industry has made great efforts in reducing fuel consumption recently. The efficiency of modern spark ignition (SI) engines has been increased by improving the combustion process and reducing engine losses such as friction, gas exchange and wall heat losses. Nevertheless, further efficiency improvement is indispensable for the reduction of CO2 emissions and the smart usage of available energy. In the previous years the Atkinson cycle realized over the crank train is attracting considerable interest of several OEMs due to the high theoretical efficiency potential. In this publication a crank train-based Atkinson cycle engine is investigated. The researched engine, a 4-stroke 2 cylinder V-engine, basically consists of a special crank train linkage system and a novel mono shaft valve train concept. The idea of a mono shaft valve train mechanism is to realize the valve actuation without the need for separate cam shafts and gears, but via a cam disk rotating crank shaft speed, thus enabling the integration of the cam disk in the crank shaft.
Technical Paper
2014-11-11
Tomomi Miyasaka, Kenta Miura, Norikuni Hayakawa, Takashi Ishino, Akira Iijima, Hideo Shoji, Kazushi Tamura, Toshimasa Utaka, Hideki Kamano
Supercharged direct-injection engines are known to have a tendency toward abnormal combustion such as spontaneous low-speed pre-ignition and strong knock because they operate under low-speed, high-load conditions conducive to the occurrence of irregular combustion. It has been hypothesized that one cause of such abnormal combustion is the intrusion of engine oil droplets into the combustion chamber where they become a source of ignition. It has also been reported that varying the composition of engine oil additives can change susceptibility to abnormal combustion. However, the mechanisms involved are not well understood, and it is not clear how the individual components of engine oil additives affect autoignition. In this study, abnormal combustion experiments were conducted to investigate the effect on autoignition of a calcium-based additive that is typically mixed into engine oil to act as a detergent. The experiments were performed with a single-cylinder 4-cycle gasoline engine using a primary reference fuel (PRF 50) into which the calcium salicylate (CaSa)-based detergent was mixed at various ratios.
Technical Paper
2014-11-11
Norikuni Hayakawa, Kenta Miura, Tomomi Miyasaka, Takashi Ishino, Akira Iijima, Hideo Shoji, Kazushi Tamura, Toshimasa Utaka, Hideki Kamano
Spontaneous low-speed pre-ignition, strong knock and other abnormal combustion events that occur in supercharged direct-injection engines are viewed as serious issues. The effects of the engine oil and the components of engine oil additives have been pointed out as one cause of such abnormal combustion. However, the mechanisms involved have yet to be elucidated, and it is unclear how the individual components of engine oil additives influence autoignition. This study investigated the effect on autoignition of boundary lubricant additives that are mixed into the engine oil for the purpose of forming a lubricant film on metal surfaces. A high-speed camera was used to photograph and visualize combustion through an optical access window provided in the combustion chamber of the 4-cycle naturally aspirated side-valve test engine. Spectroscopic measurements were also made simultaneously to investigate the characteristics of abnormal combustion in detail. Combustion experiments were conducted using a primary reference fuel (PRF 50) to which various zinc dithiophosphate (ZnDTP)- and molybdenum dithiocarbamate (MoDTC)-based additives were added in volumetric ratios ranging from 0-0.7% as typical boundary lubricant additives.
Technical Paper
2014-11-11
Abhinav Tomar
The original diesel engine is a four-stroke, Ford diesel engine with a compression ratio of 22.9:1. In order to accommodate CNG in diesel engine, the compression ratio has to be reduced to prevent knock. Computational Fluid Dynamics (CFD) method using ANSYS simulation software is used for this purpose. The objective of this study is to investigate the effects of different compression ratio on the performance of a diesel engine operating on a dual fuel system using Compressed Natural Gas (CNG) as the main fuel. The engine performance will be investigated in terms of the mixing quality of CNG and air before injection of diesel fuel, temperature and pressure distribution. Based on the simulation results, the optimum compression ratio chosen to operate the CNG-diesel engine without knock is 16.6:1. At this compression ratio, the engine can operate until the normal operating load condition where the wall temperature is 373 K before the engine was knocking.
Technical Paper
2014-11-11
Yuichi Seki, Keito Negoro, Norimasa Iida, Katsuya matsuura, Hiroshi Sono
This work investigates effects of gas inhomogeneity induced by droplets of fuels and oils on the auto ignition timing and temperature in the direct-injection spark ignition (DISI) engine by means of detailed numerical calculation using multi zone model. Recent researchers pointed out that droplets are made of fuels and oils which mix on the cylinder liner and released from the cylinder liner. During the compression stroke released droplets reach the auto ignition temperature before flame propagation induced by spark ignition. It is called Pre-ignition. When pre-ignition occurring, sometimes severe oscillation which is called Super-knock happens and damages the engine severely. In combustion chamber, there is inhomogeneity caused by temperature and mixture distribution. As for temperature, it is very hot in the center of the combustion chamber, while mixture around the cylinder liner is a relatively low temperature under the influence of the coolant. Concerning fuel distribution, it is caused by direct injection of fuel.
Technical Paper
2014-11-11
Francesco Catapano, Silvana Di Iorio, Paolo Sementa, Bianca Maria Vaglieco, Marcello Fiaccavento, Francesco Giari, Antonio Marchetti
This paper deals with the investigation of anomalous phenomena during the cranking phase of a spark ignition small engine, in particular backfire. The growing interest of this abnormal combustion is due to the use of fuels with different chemical-physical properties with respect to gasoline, that can affect especially the cranking phase of the engine. In this work the influence of the composition of the fuel on backfire was studied. In particular the investigation was focused on the presence of ethanol in the fuel. The experimental activity was carried out in an optically accessible engine derived from a 4-stroke spark ignition engine for two-wheel application. The test bench was instrumented and adapted in order to simulate the engine conditions similar to the ones that lead to the anomalous auto-ignition in the intake duct during the reverse rotation of the engine. Two different test procedures have been developed with the aim of promoting the auto-ignition at the intake. All the major engine parameters were measured, such as the in-cylinder pressure, the pressure at the exhaust and at the intake; in order to characterize the engine condition and to monitor the auto-ignition.
Technical Paper
2014-11-11
Takahiro MASUDA, Kouji SAKAI, Yuki YAMAGUCHI, Jun-ichi KAKU, Hirobumi NAGASAKA
This paper proposes a novel engine starter system composed of a small-power electric motor and simple mechanical devices. The system makes it possible to design more efficient starter-generators than conventional systems, and especially, it is effective to restart engines equipped with idling stop systems. Recently, several idling stop systems have been proposed for motorcycles to achieve intelligent start-up functions and highly-efficient generation. One of challenges of the idling stop systems is downsizing of starter motors. However, there are real limitations to downsize the motors in the conventional idling stop systems, since the systems utilize forward-rotational torque of the motors to compress mixture gas in cylinders. Our study exceeds the limitations of the downsizing by exploiting combustion energy instead of electric energy to run over a first compression top dead center. The starter system described in this paper consists of (A) an electric motor which can rotate a crank shaft both forward and backward, (B) a cam-train to drive an intake valve during an exhaust stroke in a backward rotation, and (C) a control unit to inject and ignite at arbitrary timing.
Technical Paper
2014-11-11
Christian Zinner, Reinhard Stelzl, Stephan Schmidt, Stefan Leiber, Thomas Schabetsberger
There are several reasons for equipping an internal combustion engine with a turbo charger. The most important motivation for motorcycle use is to increase the power to weight ratio. Additionally, the importance of reducing CO2-emissions is increasing even for power sport applications. These two motives, the CO2 reduction on the one hand and the increase of the power to weight ratio on the other hand, were the main drivers for the presented investigation. Focusing on the special boundary conditions of motorcycles, like the wide engine speed range or the extraordinarily high demands on response behavior, automotive downsizing technologies cannot be transferred directly to this field of application. This led to the main question: Is it possible to design a turbo charged motorcycle engine with satisfactory drivability and response behavior? The layout of a charged motorcycle engine, as presented in two previous papers, was derived by simulation and had to be verified by experimental investigations.
Technical Paper
2014-11-11
Vipin Sukumaran T., Sumith Joseph
In recent past, the two stroke vehicle manufacturers are continuously motivated to develop extreme low emission vehicle for meeting the requirements of emissions regulations. To achieve this emission compliance, manufacturers have developed engines with better induction system, improved ignition timings, increased compression ratio (C.R) and larger after-treatment devices. As an effect of above changes, engine operating temperatures are quite high which reduces the block-piston life. Even though, typical two stroke engines are forced cooled engines, there is a lot of potential for optimizing block cooling to reduce maximum liner temperature and block gradient for enhancing block-piston durability. This paper presents an experimental study of various measures to reduce liner temperature for a two stroke, single cylinder 70 c.c. engine used for two wheeler application. By studying the cooling air flow around the block and block to interface parts heat transfer, the following parts were redesigned to reduce maximum liner temperature – exhaust gasket, base gasket, cooling fan profile and cooling cowl.
Technical Paper
2014-11-11
Enrico Mattarelli, Carlo Alberto Rinaldini, Giuseppe Cantore, Enrico Agostinelli
The paper compares two different design concepts for a range extender engine rated at 30 kW at 4500 rpm. The first project is a conventional 4-Stroke SI engine, 2-cylinder, equipped with port injection and a 3-way catalyst. The second is a new type of 2-Stroke loop scavenged SI engine, featuring a direct gasoline injection and a patented rotary valve for enhancing the induction and scavenging process. Air is delivered to the 2-stroke engine by means of a piston pump, arranged as a second cylinder, with its axis at 90° from the main one. In this way, the crankcase and the crankshaft of both analyzed engines may be almost identical, despite the different operating cycle. The combustion system of the 4-Stroke engine is a conventional 4-valve pentroof design, while the 2-Stroke engine has got a hemispheric dome, with close-spaced spark plug and injector. The only valve installed on the 2-Stroke engine is the patented rotary valve, revving at the same speed of the engine. Both power units have been virtually designed with the help of CFD simulation.
Technical Paper
2014-11-11
Ken Fosaaen
Global concerns over pollution have led to increasingly strict emissions legislation targeting small engines, which currently pollute at a much greater level than modern multi-cylinder automotive engines. Closed-loop control may be required to meet many future legislation requirements; however, such systems can be impractical due to high added component costs. A necessary component for closed-loop engine control is an oxygen sensor. Existing automotive oxygen sensors are too large, require too much power, and far too expensive to be suitable for the vast majority of the global small engine applications; therefore, some manufacturers have developed smaller and/or unheated versions based on their existing sensors to meet this emerging need. The ability to miniaturize resistive based sensors well below that of traditional Nernst (zirconia based) oxygen sensors affords the opportunity to meet future emissions standards with less of an impact on cost. In this study, a sub-miniature resistance-based narrowband oxygen sensor was developed and its response to various exhaust lambda values was characterized at various temperatures.
Technical Paper
2014-11-11
Ryutaro Shinohara
We have tentatively manufactured the prototype model of exhaust heat recovery heat exchanger and carried out the heat transfer and pressure drop performance tests on it. This prototype (P.T.) is characterized that the overall heat transfer coefficient is less affected by the change of the hot air mass flow rate than that of the mass-produced model (M.P.) and overall heat transfer coefficient of the prototype exceeds that of the mass-produced under the Rel range of 1500. We have found that the changes of overall heat transfer coefficient are caused by the variation of the thermal resistance of hot air side and the thermal resistance consists of the fin effective heat transfer coefficient and the tube hot air side heat transfer coefficient from equation of the thermal conductance. We have calculated the fin effective heat transfer coefficient using Pohlhausen equation and fin efficiency, and obtained the tube hot air side heat transfer coefficient from the test results. We have compared these coefficients and found that the fin effective heat transfer coefficient of the prototype is much lower, but the tube hot air side heat transfer coefficient of the prototype is much higher than that of the mass-produced.
Technical Paper
2014-11-11
Giuseppe Danilo Rossi, Sara Gronchi, Matteo Gasperini, Bernardo Celata, Raffaele Squarcini
Electrical oil pumps are used in order to reduce the engine car emissions thanks to the optimization of the absorbed energy and motor efficiency. The present trend to obtain this improvement of the motor efficiency is the electrification of the auxiliary components that can be driven independently from the engine shaft. In this field, the electrical oil pumps are one of the most required components used for automatic transmissions as well as for the main lubrication system. An electrical oil pump is driven by an electric motor with its electronic control system. The electric motor should generate an available torque higher than the total torque requested by the hydraulic mechanism, to allow the pump generating the expected performances. The pump type has been chosen thanks to PPT experience in the development of hydraulic pumps, the “G-rotor” solution, which is a particular shape of gears, is the best compromise in terms of noise, dimensions, robustness and packaging. In order to design an optimized electrical oil pump it is important to evaluate the absorbed torque by the hydraulic mechanism.
Technical Paper
2014-11-11
Tetsuya Osakabe
As gasoline prices have crept up in recent years, demand for higher fuel efficiency has increased also for motorcycles. Growing attention has been paid to how we can comprehensively improve fuel efficiency by raising the efficiency of the generator and other auxiliary equipment. This paper describes how we improved the power generation efficiency of a single-phase motorcycle generator of outer-rotor type by reducing electric losses (i.e. iron loss and copper loss) and improving magnetic flux through electromagnetic field analysis. Through electromagnetic field analysis, we first distinguished iron loss and copper loss. Then, focusing on the iron loss that we found inferiority, we modified the thickness and material of the stator core and improved power generation efficiency. Another source of iron loss was the non-magnetic protection cover of the magnets in the rotor. We reduced iron loss by drilling holes of that cover into where the magnet and the stator core faced each other and the magnetic flux passed through.
Technical Paper
2014-11-11
Lakshmy Neela, Klaus Grambichler
Automotive Magnetic Sensor market is expanding day by day serving a lot of automotive applications. Crankshaft sensors are mainly used to monitor the position or rotational speed of the crankshaft, thereby controlling the ignition system timing and enabling misfire detection. Passive VR (Variable Reluctance) sensor and Active Hall effect sensor are the two commonly used low cost sensors in automotive crankshaft applications. An extensive research regarding the functional and physical attributes of both sensor technologies (incorporating innovative designs and different application scenarios) has been performed providing a wide overview of the benefits and ill-effects of both the technologies and a comprehensive guide for customers in sensor selection. Cost is an important factor driving today’s automotive market. Comparison of overall costs of active and passive systems starting with the sensing element, additional circuitry for signal shaping till package and assembly process from system level has been studied in detail.
Technical Paper
2014-11-11
Giovanni Vichi, Isacco Stiaccini, Alessandro Bellissima, Ryota Minamino, Lorenzo Ferrari, Giovanni Ferrara
A condition monitoring activity consists in the analysis of several informations from the engine and the subsequent data elaboration to assess its operating condition. By means of a continuous supervision of the operating conditions the performance of an internal combustion engine can be maintained at a high level with both long availabilities and design-level efficiencies. The growing use of turbocharger (TC) not only in automotive field but also for off-road small vehicles or for small stationary applications, suggests to use the TC speed as a possible feedback of engine operating condition. Indeed, the turbocharger behaviour is connected to the thermo and fluid-dynamic conditions at the engine cylinder exit: this feature suggests that the turbocharger speed could give useful data about the engine cycle. In this study the authors describe a theoretical and numerical analysis focused on the turbocharger speed in a four stroke turbo-diesel engine. The purpose of this study is to highlight whether the turbocharger speed allows one to detect the variation of the engine parameters.
Technical Paper
2014-11-11
Francisco Payri, J. Javier Lopez, Benjamin Pla, Diana Graciano Bustamante
Direct injection compression ignited (CI) engines are today’s most efficient engine technology, granting efficiencies exceeding 40% for their optimal operation point. In addition, a strong technological development has allowed the CI engine to overcome its traditional weak points: both its pollutant emissions and the gap in specific power regarding its competitor, i.e. the spark ignited engine, have been noticeably reduced. Particularly, the increase in specific power has leaded to the downsizing as an effective method to improve vehicle efficiency. However, the cylinder displacement in current CI engines is barely lower than 0.4 liters and authors do not know any CI engine with a cylinder displacement lower than 0.25 liters. For some applications (urban light duty vehicles, Range Extenders...) it may be interesting to reduce the engine displacement to address power targets around 20kW with high efficiencies. This paper assesses the thermo- and fluid-dynamic limitations which make challenging extending the application of automotive CI engines to the low power region, namely, space limitations for injection and combustion processes, increase of surface-to-volume ratio giving rise to higher heat losses and limits related to the air management, most notably with turbocharging, due to the reduction in turbocharger efficiency with decreasing size.
Technical Paper
2014-11-11
Takashi ONISHI
1. The main issues and conclusions. All of diesel engines over 19 kW horse power in North America, which are mainly used for agriculture, landscape and construction application, are required to reduce further Nitrogen Oxides (NOx) and Particle Matter (PM) by EPA emission regulation. Especially, it is necessary to reduce PM emission up to one-tenth as conventional. In addition to improve combustion in the engine, it is needed to add the engine exhaust-gas aftertreatment device to reduce PM emission. Then it is essential to prevent increasing NOx emission by improving combustion. We developed the 1.5 L non-road IDI (In-Direct Injection) diesel engine with mechanical fuel injection system, which met EPA Tier 4 regulation. This paper introduces the techniques to achieve lower exhaust emissions, those are newly-developed exhaust-gas aftertreatment system. 2. The process by which the conclusions were reached. Techniques for lower exhaust emissions It is important for small industrial diesel engines to be compact to install machineries.
Technical Paper
2014-11-11
Giancarlo Chiatti, Erasmo Recco, Ornella Chiavola, Silvia Conforto
In the last years environmental issues of IC engines have promoted the need to assess new strategies in order to obtain a reduction not only of pollutants emission in atmosphere, but also of noise radiation. Engine noise can be classified into aerodynamic noise of intake and exhaust systems and surface radiated noise. Sources identification and analysis is essential to evaluate the individual contribution (injection, combustion, piston slap, turbocharger, oil pump, valves) to the overall engine noise with the aim of selecting appropriate noise reduction strategies. In previous papers, the attention was addressed towards the combustion related noise emission. The research activity was aimed at selecting the optimal placement for the microphone in which the signal was characterized by a strong correlation with the in-cylinder pressure development during the combustion process. The analysis and the processing of the sound emission allowed to isolate the acoustic contribution mainly due to the combustion event.
Technical Paper
2014-11-11
Hiroki Ikeda, Norimasa Iida, Hiroshi Kuzuyama, Tsutomu Umehara, Takayuki Fuyuto
A combustion method called Noise Cancelling Spike (NC-Spike) Combustion has been reported in the co-author’s previous paper, which reduces combustion noise in pre-mixed charge compression ignition (PCCI) with split injection. This NC-Spike Combustion uses interference of the following “spike” of pressure rise (heat release) on the preceding peak of pressure rise. The overall combustion noise was reduced by lowering the maximum frequency component of the noise spectrum. The period of this frequency is two times of the time interval between the two peaks of the pressure rise rate. This maximum load range of conventional PCCI combustion is limited by the combustion noise, since the maximum pressure rise rate increases as the amount of injected fuel increases. The NC-Spike Combustion has a potential to extend of the operating range of PCCI combustion. In this paper, we investigates feasibility and controllability of the two-peak heat release rate during high temperature heat release by adding fuel in the adiabatic compression process of pre-mixed gas.
Technical Paper
2014-11-11
Yuzuru Nada, Yusuke Komatsubara, Thang Pham, Fumiya Yoshii, Yoshiyuki Kidoguchi
In this study, we investigated relationship between flame behaviors and NOx emissions using a rapid compression machine incorporating a small combustion chamber with a bore diameter of 60 mm and a displaced volume of 100 cc. A total gas sampling device was used to measure the NOx concentration in total gases existing in the combustion chamber at a designated time, which allows the evaluation of NOx production rate in combustion process. Temporal temperature distributions in the chamber were measured with high speed 2-color thermometry. Two types of injectors with 4 and 8 injection holes were used in the experimental trials. Gas oil (JIS #2) was used as the fuel, and injected into the chamber at pressures of 100 MPa and 160 MPa. Ambient pressures at fuel injection timing were set to 4 MPa and 8 MPa in order to investigate the effect of supercharging on combustion behaviors in the chamber. The temperature of ambient air was kept constant at 850 K in all experimental trials. A NOx concentration measured with the total gas sampling device increases at a stage of diffusion combustion following after a premixed combustion stage.
Technical Paper
2014-11-11
Alex K. Rowton, Joseph Ausserer, Marc D. Polanka, Paul Litke, Keith Grinstead
As internal combustion engines (ICEs) decrease in displacement, their cylinder surface area to swept volume ratio increases. Examining power output of ICEs with respect to cylinder surface area to swept volume ratio shows that there is a dramatic change in power scaling trends at approximately 1.5 cm-1. At this size, thermal quenching becomes the dominant thermal loss mechanism and performance and efficiency characteristics suffer. Furthermore, small ICEs (>1 cm-1) have limited technical performance data compared to ICEs in larger size classes. Therefore, it is critical to establish accurate performance figures for a family of geometrically similar engines in the size class of approximately 1.5 cm-1 in order to better predict and model the thermal losses as well as other phenomena that contribute to lower efficiencies in small ICEs. The engines considered in this scaling study were manufactured by 3W Modellmotoren, GmbH. In particular, they are the 3W-28i, 3W-55i, and 3W-85Xi which have a cylinder surface area to swept volume ratio of 1.81 cm-1, 1.46 cm-1, and 1.28 cm-1 respectively.
Technical Paper
2014-11-11
Stefan Krimplstätter, Franz Winkler, Roland Oswald, Roland Kirchberger
Graz University of technology has presented several applications of its 2-stroke LPDI (low pressure direct injection) technology in the previous years (SAE Paper No´s.: 2005-32-0098, 2006-32-0065, 2008-32-0059, 2010-32-0019). In order to improve the competitiveness of the 2-stroke LPDI technology, an air cooled 50cm³ scooter application has been developed. All previous applications have been liquid cooled. The application demonstrates the EURO 4 (2017) ability of the technology and shows that the 2S-LPDI technology can also be applied to low cost air-cooled engines. Hence the complete scooter and moped fleet can be equipped with this technology in order to fulfil on the one hand the emission standards and on the other hand the COP (conformity of production) requirements of Euro 4 emission stage. The paper will present the Euro 4 results of the scooter and describe the very simple conversion process of the existing carburetor engine to the LPDI version. Euro 4 results can be achieved with conventional exhaust system architecture known form nowadays Euro 2 applications.
Technical Paper
2014-11-11
Federico Brusiani, Gian Marco Bianchi, Cristian Catellani, Marco Ferrari, Paolo Verziagi, Dario Catanese
Most of the handheld application are equipped with a Two stroke SI engine. The advantage of this engine are known but one of the problem of this applications is to design air cooling system with high efficiency. One of the main problem to cool the two stroke engine for hand held applications like chainsaw, brush cutter, blower and so on is obtain compact design of the application but in the mean time to have the correct air flow in all conditions. This paper describes a CFD methodology to optimize the air flow around the two stroke engine and identify the potential improvement of this system to increase the cooling efficiency.
Viewing 1 to 30 of 39881