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Viewing 1 to 30 of 39884
Technical Paper
2014-11-11
Koorosh Khanjani, Jiamei Deng, Andrzej Ordys
Controlling Variable Coolant Temperature in Internal Combustion Engines and Its Effects on Fuel Consumption Koorosh Khanjani ; Roehampton Vale Campus, Kingston University, Friars Avenue, London SW15 3DW; K1155703@kingston.ac.uk; Tel: +44 (0)208 417 4730; Jiamei Deng ; Roehampton Vale Campus, Kingston University, Friars Avenue, London SW15 3DW; J.Deng@kingston.ac.uk; Tel: +44 (0)208 417 4712; Andrzej Ordys ; Roehampton Vale Campus, Kingston University, Friars Avenue, London SW15 3DW; A.Ordys@kingston.ac.uk; +44 (0) 208 417 4846; Abstract: Increasing the efficiency and durability of internal combustion engines is one of the major concerns of engineers in development of modern road vehicles. Emission legislations are becoming stricter each year forcing manufacturers to deploy sophisticated engine control strategies to transfer more of the fuel chemical energy into power output. Internal combustion engines have now been equipped with electronic engine management control units which consist of precise measurements and performance by means of various sensors and actuators.
Technical Paper
2014-11-11
Klaus Stuhlmüller
In a microcontroller-operated ignition process, the combustion is dependent on three important criteria: Spark burn duration, ignition voltage, and ignition spark energy. These criteria must be adapted exactly to the engine's individual requirement profile to ensure optimal combustion. In each operating state and operating environment, optimum ignition is ensured by continuously analyzing sensor values. Engine manufacturers continue to be faced with the challenge of ensuring that the machine runs as smoothly and quietly as possible. Increased spark duration and higher energy of the ignition spark enable improved combustion of the gasoline-air mixture in the combustion compartment. This article describes an electrical ignition process using an array of multiple coils and a magnetic generator that is rotating in sync with the machine. During this process the magnetic field temporarily flows through the coils and generates a sequence of magnetic flow variations per rotation. This induces corresponding half-waves of alternating voltage in the coils of the ignition module.
Technical Paper
2014-11-11
Horizon Walker Gitano, Ray Chim, Jian Loh
Recent concern over air quality has lead to increasingly stringent emissions regulations on ever smaller displacement engines, resulting in the application of Electronic Fuel Injection to the 100cc-200cc class 2-wheelers in many countries. In the pursuit of ever smaller and less expensive EFI systems, a number of unique technologies are being explored, including resistive type oxygen sensors. In this paper we investigate the application of a small resistive oxygen sensor to a small motorcycle EFI system. Measurements of the exhaust system temperatures, and Air/Fuel Ratio ranges are carried out, and compared to the sensors response over this range to create an estimate of the sensors in-use performance. Actual sensor and temperature measurements are then compared to both a standard zirconia switching type oxygen sensor, and a wide-band oxygen sensor. Results are analyzed and indicate that the resistive type oxygen sensor should be capable of allowing the EFI controller to successfully control the vehicles AFR in all operating modes with a faster “light off” time, and lower overall current draw when compared to the standard heated zirconia sensor.
Technical Paper
2014-11-11
Hideyuki Ogawa, Gen Shibata, Yuhei Noguchi, Mutsumi Numata
Simultaneous reductions of NOx and particulate emissions as well as the improvements in the thermal efficiency and the engine performance with emulsified blends of water and diesel fuel are reported. A reduction in combustion temperature and promotion of premixing with larger ignition delays due to vaporization of the water in the fuel has been suggested as the mechanism. However, details of the combustion process and the mechanism of the emission reduction is not fully elucidated. In this research diesel like combustion of emulsified blend of water and diesel fuel in a constant volume chamber vessel was visualized with high speed color video and analyzed with a 2-D two color method. The shadowgraph images were also recorded and the rate of heat release was obtained from pressure data in the combustion chamber. An emulsified blend of water and diesel fuel (JIS. No. 2) with 26 vol% water and 4 vol% surfactant was used as the test fuel, and the diesel fuel in the emulsion without water and the surfactant was used as a reference.
Technical Paper
2014-11-11
Stefania Falfari, Claudio Forte, Federico Brusiani, Gian Marco Bianchi, Giulio Cazzoli, Cristian Catellani
Faster combustion and lower cycle-to-cycle variability are the two mandatory tasks in the naturally aspirated engines for lowering the emission levels and for increasing the efficiency. Generally speaking the promotion of a stable and coherent tumble structure is largely believed in literature to enhance the in-cylinder turbulence accelerating combustion process. In small PFI engine layout and weight constraints limit the adoption of more advanced concepts. The turbulence generation process is strictly related to the tumble vortex deformation process: during the compression stroke the tumble vortex is deformed, accelerated and its breakdown in smaller eddies leads to the turbulence enhancement process. The prediction of the final level of turbulence for a particular engine operating point is crucial during the engine design process because it represents a practical comparative means for different engine solutions. The tumble ratio parameter value represents a first step toward the evaluation of the turbulence level at ignition time, but it has an intrinsic limit.
Technical Paper
2014-11-11
Naoya Ito, Akira Terashima, Junki Sahara, Takashi Shimada, Masanori Yamada, Akira Iijima, Tomohiko Asai, Mitsuaki Tanabe, Koji Yoshida, Hideo Shoji
Lean burn is a very effective way to substantially improve the thermal efficiency of internal combustion engines. A major issue involved in applying a lean-burn process to a spark-ignition engine is to secure stable ignition and combustion. Homogeneous Charge Compression Ignition (HCCI) combustion is one technology for accomplishing rapid combustion of a lean premixed air-fuel mixture. However, because the mixture is autoignited by piston compression in an HCCI engine, controlling the ignition timing is a crucial issue. In addition, another issue of HCCI engines is the narrow range of stable operation owing to the occurrence of misfiring at low loads and extremely rapid combustion at high loads. As an approach to resolving these issues, this study focused on the use of low-temperature plasma as an ignition technique for inducing stable autoignition in an HCCI engine. Specifically, the use of a streamer discharge was investigated for controlling HCCI ignition and combustion. A continuous streamer discharge was generated in the center of the combustion chamber of a 2-stroke engine that allowed visualization of the entire bore area.
Technical Paper
2014-11-11
Keisuke Mochizuki, Takahiro Shima, Hirotaka Suzuki, Yoshihiro Ishikawa, Akira Iijima, Koji Yoshida, Hideo Shoji
Homogeneous Charge Compression Ignition (HCCI) has attracted a great deal of interest as a combustion system for internal combustion engines because it achieves high efficiency and clean exhaust emissions. However, HCCI combustion has several issues that remain to be solved. For example, it is difficult to control engine operation because there is no physical means of inducing ignition. Another issue is the rapid rate of heat release because ignition of the mixture occurs simultaneously at multiple places in the cylinder. The results of previous investigations have shown that the use of a blended fuel of DME and propane was observed that the overall combustion process was delayed, with that combustion became steep when injected propane much. This study focused on expanding the region of stable engine operation and improving thermal efficiency by using supercharging and blended fuels. The purpose of using supercharging were in order to moderated combustion. In addition, the purpose of using blended gaseous fuels were find out effective use of gaseous fuels.
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.
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
Ludek Pohorelsky, Pavel Brynych, Jan Macek, Pascal Tribotte, Gaetano De Paola, Cyprien Ternel
The objective of this paper is to present the results of the GT Power calibration with engine test results of the air loop system technology down selection described in the SAE Paper No. 2012-01-0831.Two specific boosting systems were identified as the preferred path forward: (1) Super-turbo with two speed Roots type supercharger, (2) Super-turbo with centrifugal mechanical compressor and CVT transmission both downstream a Fixed Geometry Turbine. The initial performance validation of the boosting hardware in the gas stand and the calibration of the GT Power model developed is described. The calibration leverages data coming from the tests on 2 cylinder 2-stroke 0.73L 45kW diesel engine. The initial flow bench results suggested the need for a revision of the turbo matching due to the big gap in performance between predicted maps and real data. This activity was performed using Honeywell turbocharger solutions spacing from fixed geometry waste gate to variable nozzle turbo (VNT). New simulations results recommend VNT as it offers a higher potential to reduce BSFC with increase power and low end torque output than the original matching.
Technical Paper
2014-11-11
Luigi Allocca, Alessandro Montanaro, Rita Di Gioia, Giovanni Bonandrini
In the next future, improvements of direct injection systems for spark-ignited engines are necessary for the potential reductions in fuel consumptions and exhaust emissions. The admission and spread of the fuel in the combustion chamber is strictly related to the injector design and performances, such as to the fuel and environmental pressure and temperature conditions. In this paper the spray characterization of a GDI injector under normal and flash-boiling injection conditions has been investigated. A customized sensing of the injector nose permitted the temperature control of the nozzle up to 90 °C while a remote-controlled thermostatic device allowed the fuel heating from ambient to 120 °C. An axially-disposed, 0.200 mm in diameter, single-hole injector has been used with l/d ratio equal to 1 and static flow@100 bar: 2.45 g/s, using iso-octane as mono-component fluid. A 1.0 ms duration single pulse strategy has been adopted at the injection pressure of 10 MPa. The spray evolved in a quiescent optically-accessible vessel pressurize at 0.05, 0.1 and 0.3 MPa at ambient temperature of the gas (N2).
Technical Paper
2014-11-11
Ryosuke Ibata, Hirotaka Kawatsu, Tetsuya Kaneko, Kenji Nishida
Motorcycles with small displacement engines (hereafter called small motorcycles) are used in large numbers and the improvement of the fuel economy is one of the important issues to be solved from the global environmental viewpoint. Spark advance control is one of the technologies for fuel economy improvements. To apply this technology, it generally requires being equipped with a throttle position sensor to detect engine loads. However, many of these small motorcycles cannot be equipped with a throttle position sensor because of their stringent requirements for affordable prices. Meanwhile, the onboard technology for estimating engine loads has been developed by using “Δω” (delta-omega), which represents the amplitude of variations in crankshaft angular velocity within a four-stroke cycle. This study aimed at the achievement of the system that could substitute for a throttle position sensor, which outputs an on-off signal to distinguish the engine load levels into two ranges (hereafter called throttle switch), using engine load estimation technology based on Δω.
Technical Paper
2014-11-11
Daniela Siano, Fabio Bozza, Danilo D'Agostino, Maria Antonietta Panza
In the present work, an Auto Regressive (AR) model and a Discrete Wavelet Transform (DWT) are applied on vibrational signals, acquired by an accelerometer placed on the cylinder block of an internal combustion engine, for knock detection purposes. To this aim, vibrational signals are acquired on a four cylinder Spark Ignition engine for different engine speeds and spark advances. The same analysis is executed by also using the traditional MAPO (Maximum Amplitude of Pressure Oscillations) index, applied on the in-cylinder pressure waveforms. The results of the three methods are compared and in depth discussed to the aim of highlighting the pros and cons of each methodology. In particular, the problem of fixing a constant threshold level for each running condition is afforded and solved. The examples presented show the capability of the vibration based detection algorithms in accurately monitor the presence of heavy or soft knock phenomena, and to determine its intensity. Therefore, the possibility of implementation in modern on-board control units is foreseen, as well.
Technical Paper
2014-11-11
Christian Schweikert, David Witt, Dirk Schweitzer, Marco Nicolo, Liu chen
The market potential for products such as scooters and small motorcycles is already self sustaining. However, other applications for small engines can be more fragmented with a wide variety of requirements for the engine control unit. Consequently, the engine control unit is designed to accommodate more features than are necessary for a given application to cover a broader market. The flip side of this approach is to design the engine control unit for a limited application reducing the market size. Neither approach creates a cost efficient product for the producer. It either supplies the market with an electronic control unit that has features not being utilized (wasted costs) or a unit that has limited capabilities reducing the economies of scale (higher costs). When these designs are developed using discrete components these inefficiencies are exacerbated. Integration of these functions at the semiconductor level can mitigate these costs, improve the thermal performance or expand the functional capabilities to include additional vehicular control aspects in the electronic control unit.
Technical Paper
2014-11-11
Paolo Gai, Francesco Esposito, Riccardo Schiavi, Marco Di Natale, Claudio Diglio, Michele Pagano, Carlo Camicia, Luca Carmignani
The design and development of the electronic architecture and the control software integrated inside the next generation of two wheelers will be one of the major challenges for small engine products. The need for optimal fuel consumption and emission control, paired with strict safety requirements will force many manufacturers to reconsider their electronic architecture adding complex functions with the risk of incurring in additional costs to be carefully planned in the product roadmap. These challenges have already been tackled twenty years ago by the automotive manufacturers, generating a set of standards in an attempt to improve productivity and quality by standardization, interoperability and competition on functional content. The result has been the development of distributed software architectures based on the CAN bus and the OSEK/VDX[8] standard, and more recently with the AUTOSAR[4] initiative. Therefore, a set of automotive standards are available and can be used as an inspiration as they share common goals such as portability, reusability, and limited footprint; on the other side, the inherent complexity and license cost of complete commercial bundles makes the adoption of these automotive standards impracticable for low-cost engines.
Technical Paper
2014-11-11
Christian Steinbrecher, Bastian Reineke, Wolfgang Fischer, Henning Heikes, Thorsten Raatz
Equipping low cost 2-wheelers with engine management systems (EMS) enables not only a reduction of emissions but also an improvement in fuel consumption and system robustness. These benefits are accompanied by initially higher system costs compared to carburetor systems. In order to reduce the system costs, intelligent software solutions are developed at Bosch, which enable a reduction of the necessary sensors for a port fuel injection system (PFI) and furthermore provide new possibilities for combustion control. One example for these intelligent software solutions is model based evaluation of the engine speed signal. By use of the information in this signal, characteristic features like air charge, indicated mean effective pressure (imep) and combustion phasing are derivable. The present paper illustrates how these features could be used to reduce the system costs and how to improve the fuel consumption and system robustness. Especially in the low cost segment the system robustness is challenged by significant bike-to-bike variations in e.g. compression ratio or valve timing.
Technical Paper
2014-11-11
Yuta Kugimachi, Yusuke Nakamura, Norimasa Iida
Homogeneous Charge Compression Ignition (HCCI) engine has several advantages of high thermal efficiency and low emission over the conventional Spark Ignition (SI) engine and Compression Ignition (CI) engine. Although one way to achieve higher loads without knocking in HCCI engine is the combustion phasing retard, it is difficult to control a combustion-phasing since there is no external combustion trigger for controlling ignition like spark ignition and diesel fuel injection. Futhermore, recent researches show that too much combustion-phasing retard leads to unacceptable cycle-to-cycle variation of Pressure Rise Rate (PRR) and Indicated Mean Effective Pressure (IMEP). Therefore, it is necessary to construct a HCCI combustion control system to control a combustion-phasing at constant phasing in the expansion stroke accurately to get the high load without knocking. This study investigates the HCCI combustion control system and the algorithm as a means of extending the limit of IMEP of HCCI combustion at high load for realize HCCI engine fuelled with Dimethyl Ether (DME).
Technical Paper
2014-11-11
Jens Steinmill, Ralf Struzyna
Authors: Dipl.-Ing. Jens Steinmill, Dipl.-Ing. Ralf Struzyna, Prof.Dr.-Ing. Wolfgang Eifler Department for Combustion Engines, Ruhr-University Bochum , D-44801 Bochum, Germany Contact: e-mail: Jens.Steinmill@rub.de | phone: +49234-3227404 | fax: +49234-3207404 The control and regulation of internal combustion engines for use in nano-CHP units has not yet reached the state of the art, which is common in the automotive industry. Frequently, the engines are operated in a stationary operating point without adjustment of the combustion process. In the automotive sector is the torque structure prior art. The requested torque by driver, which is derived from the accelerator pedal position is coordinated with the other torque requests and converted in the simplest case, into a desired air-charge, ignition angle and amount of fuel. The actuators on the engine, for example, Throttle, ignition and injectors are triggered. At a nano-CHP unit, the target size of the motor controller is is not mechanical torque, but thermal and mechanical power.
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
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
Kazushi Tamura, Toshimasa Utaka, Hideki Kamano, Norikuni Hayakawa, Tomomi Miyasaka, Takashi Ishino, Akira Iijima, Hideo Shoji
Prevention of abnormal combustion is a longstanding problem on spark-ignited engines. Engine oils leaked into combustion chambers have been reported to cause abnormal combustion through auto-ignition followed by knock. Since spontaneous ignition temperature of engine oils is in general much lower than that of fuels due to the difference of carbon number of their hydrocarbon contents, it appears that base oil composition is major determinant of engine oil-induced auto-ignition. However, the latest study showed that engine oil additive chemistry strongly affects the frequency of pre-ignition, a type of abnormal combustion caused by auto-ignition before a spark plug fires. To better understand combustion and improve engine technology, we need to clarify the mechanism of contribution of engine oil additives to abnormal combustion. When engine oils enter in a combustion chamber, non-volatile engine oil additives such as metallic compounds should be deteriorated and deposited on the combustion chamber.
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
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
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, 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
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
Alexander Shkolnik, Mark Nickerson, Nikolay Shkolnik
In this paper, we will present the development of a small (<50cc) rotary diesel internal combustion engine based on the High Efficiency Hybrid Cycle (HEHC). The cycle, which combines compression ignition (high compression ratio), constant-volume (isochoric) combustion, and over-expansion, has a theoretical efficiency of 75% using air-standard assumptions and first-law analysis. A new engine architecture dubbed the 'X' engine was developed to embody this thermodynamic cycle, and simulations show potential brake efficiency exceeding 50%. As this engine does not have poppet valves, and the gas is fully expanded before the exhaust stroke starts, the engine has potential to be very quiet compared to alternative 2-stroke and 4-stroke piston engines. Similar to the Wankel-type rotary engine, the 'X' engine has only two primary moving parts - a shaft, and a rotor, and both engine types will be compact and offer low-vibration operation. Unlike the Wankel, however, the X engine is uniquely configured to adopt the HEHC cycle and its associated efficiency and low-noise benefits.
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
Sejun Lee, Kyohei Ozaki, Takahiro Sako, Norimasa Iida
In spark ignition (SI) engines, exhaust gas recirculation (EGR) can realize reducing NOx emissions and heat loss by the low temperature combustion. However, adjusting the high level of EGR is limited because it incurs decrease of degree of constant volume and cut off flame propagation by the low laminar burning velocity. Recently, a potential of Dedicated EGR concept SI engine has been researched. This concept engine had 4 cylinders and operated with exhaust gas supplied from the single cylinder to the intake manifold. Compared with conventional SI engines, it was able to increase fuel efficiency and decrease CO, HC, and NO emissions by the high level of EGR rate 25%. However, there was a lack of analysis of the effect of various EGR compositions and EGR rates, the characteristics of Dedicated EGR concept was not enough to understand widely. In this study, numerical analysis of Dedicated EGR concept SI engine with various EGR rates was carried out for detail understanding the potential of this concept engine in terms of thermal efficiency and amount of NOx emissions.
Viewing 1 to 30 of 39884