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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Automotive Engineers
Journal Basic Information
Journal DOI :
The Korean Society of Automotive Engineers
Editor in Chief :
Volume & Issues
Volume 15, Issue 6 - Nov 2007
Volume 15, Issue 5 - Sep 2007
Volume 15, Issue 4 - Jul 2007
Volume 15, Issue 3 - May 2007
Volume 15, Issue 2 - Mar 2007
Volume 15, Issue 1 - Jan 2007
Selecting the target year
An Evaluation on Corrosion Fatigue life of Spring Steel by Compressive Residual Stress
Park, Keyung-Dong ; Ki, Woo-Tae ; Sin, Yeong-Jin ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 1~7
In this study, the influence of compressive residual stress and corrosive condition for corrosion fatigue crack was investigated, after immersing in 3.5%NaCl,
. The immersion period was performed for 90days. The fatigue characterization of a spring steel with processed shot peening were performed by considering the several corrosion environments in the range of stress ratio of 0.05 by means of opening mode displacement. By using the methods mentioned above, the following conclusions have been drawn: The fatigue life shows more improvement in the shot peened material than that in the un peened material. And the fatigue life shows improvement in ambient than in corrosion conditions. Threshold stress intensity factor range of the shot peened materials has higher than of the un peened materials. And the threshold stress intensity factor range was decreased in corrosion environments over ambient.
The Integrated Control Model for the Freeway Corridors based on Multi-Agent Approach I : Simulation System & Modeling for Optimization
Cho, Ki-Yong ; Bae, Chul-Ho ; Kim, Hyun-Jun ; Chu, Yul ; Suh, Myung-Won ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 8~15
Freeway corridors consist of urban freeways and parallel arterials that drivers can use alternatively. Ramp metering in freeways and signal control in arterials are contemporary traffic control methods that have been developed and applied in order to improve traffic conditions of freeway corridors. However, most of the existing studies have focused on either optimal ramp metering in freeways, or progression signal strategies between arterial intersections. There have been no traffic control systems in Korea that integrates the freeway ramp metering and arterial signal control. The effective control strategies for freeway operations may cause negative effects on arterial traffic. On the other hand, traffic congestion and bottleneck phenomenon of arterials due to the increasing peak-hour travel demand and ineffective signal operation may generate an accessibility problem to freeway ramps. Thus, the main function of the freeway which is the through-traffic process has not been successful. The purpose of this study is to develop an integrated control model that connects freeway ramp metering systems and signal control systems in arterial intersections. And Optimization of integrated control model which consists of ramp metering and signal control is another purpose. The design of experiment, neural network, and simulated annealing are used for optimization.
Effect of Air Conditioning System on Vehicle Fuel Economy in a Passenger Car
Kim, Dae-Kwang ; Cho, Geun-Jin ; Park, Jin-Il ; Lee, Jong-Hwa ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 16~22
Fuel efficiency is one of the major issues in regard to energy and environment. As customers desire more comfortable vehicles, increase of accessory traction force is necessary. Air conditioning system (ACS) consumes the biggest traction force among accessories, especially during summer. This means ACS is the primary object deteriorating fuel economy among accessories. Since direct measurement of traction force and fuel consumption in practical vehicle is difficult, comparison analysis is taken between vehicle with and without ACS working. For this comparison, real time measurements are carried out to know ACS traction force and fuel consumption. As a result of the comparison, a vehicle without ACS operation was 15.92% superior to a vehicle with ACS operating. It could be used as a fundamental material for improvement ACS for better fuel efficiency.
A Study on the Cooling Characteristics Improvement of TMA-Water Clathrate Compound by Ethanol
Lee, Jong-In ; Kim, Chang-Oh ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 23~28
This study aims to find out cooling characteristics of TMA(Tri-Methyl-Amine,
) 25wt%-water clathrate compound with ethanol(
) such as supercooling, phase change temperature and specific heat. For this purpose, ethanol is added as per weight concentration and cooling experiment is performed at
, cooling heat source temperature, and it leads the following result. (1) Phase change temperature is decreased due to freezing point depression phenomenon. Especially, it is minimized as
according to cooling source temperature in case that 0.5wt% of ethanol is added. (2) If 0.5wt% of ethanol is added, average supercooling degree is
and minimum supercooling is 0.8,
according to cooling heat source temperature. The restraint effect of supercooling is shown. (3) Specific heat shows tendency to decrease if ethanol is added. It is
according to cooling heat source temperature if 0.5wt% of ethanol is added. Phase change temperature higher than that of water and inhibitory effect against supercooling can be confirmed through experimental study on cooling characteristics of TMA 25wt%-water clathrate compound by adding additive, ethanol. This can lead to shorten refrigerator operation time of low temperature latent heat storage system and improve COP of refrigerator and efficiency of overall system. Therefore energy can be saved and efficiency can be improved much more.
A Study on the Automatic Operation Performance Control of Urban Rail Vehicle Using an Optimal Control
Tak, Kil-Hun ; Kim, Dong-Hwan ; Kim, Chi-Tae ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 29~37
In the automatic operation of an urban rail vehicle, a conventional PID control algorithm is applied to run the vehicle between stations within time limit and jerk limit. But the energy consumption in the automatic operation is much higher than in the manual operation. In this study, the optimal control algorithm for automatic operation is proposed to minimize energy consumption, which satisfies automatic operation for the urban rail vehicle, compared with the conventional PID control algorithm.
A Study on the Selection of Train Operation Mode Minimizing the Running Energy Consumption
Kim, Yong-Hyun ; Kim, Dong-Hwan ; Kim, Chi-Tae ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 38~48
this paper analyses how much acceleration and deceleration of urban rail vehicle should be applied and how to choose an operation mode to minimize energy consumption when train runs between stations within the fixed operation time. The decided operation pattern satisfying the minimum energy consumption becomes a target trajectory and a basis for the controller design criteria. To make this goal it grasps the characteristics of urban rail vehicle, realize operation energy model of urban rail vehicle and verity the accuracy of embodied model the Matlab simulation with the same operation result of real route. It searches for operation pattern to minimize operation energy by changing the acceleration and deceleration on the imaginative route and proposes operation pattern minimizing energy consumption by applying real operation data between stations of Seoul Metropolitan Subway Line 6.
Effect of Ambient Temperature and Droplet Size of a Single Emulsion Droplet on Auto-ignition and Micro-explosion
Jeong, In-Cheol ; Lee, Kyung-Hwan ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 49~55
The characteristics of auto-ignition and combustion process of a single droplet of emulsified fuel suspended in a high-temperature air chamber have been investigated experimentally with various droplet sizes, surrounding temperatures, and water contents. The used fuels was n-Decane and it was emulsified with varied water contents whose maximum is 30%. The high-speed camera has been adopted to measure the ignition delay and flame life time. It was also applied to observe micro-explosion behaviors. The increase of droplet size and chamber temperature cause the decrease of the ignition delay time and flame life-time. As the water contents increases, the ignition delay time increases and the micro-explosion behaviors are strengthened. The starting timings of micro-explosion and fuel puffing are compared for different droplet sizes and the amount of water contents.
Rollover Analysis of a Bus using Beam Element and Nonlinear Spring Characteristics
Park, Su-Jin ; Yoo, Wan-Suk ; Kwon, Yuen-Ju ; Kim, Jin-Bae ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 56~63
In case of bus rollover, the body structure of the bus should be designed to ensure the survival space for passengers. So, this study focuses on evaluating rollover strength through a computer simulation using the commercial code, LS-DYNA3D at the initial stage of vehicle development. For this study, section structure was modeled using a simple beam element, and impact boundary conditions required by ECE(Economic Commission for Europe) regulation No.66 were applied. In order to confirm the validity of the beam element bus model, the results compared with the test results and shell element bus model. The analysis errors from beam element bus model are due to the difference in strain energy of joint area between beam and shell model. In this study, a method for the joint modeling was suggested by using nonlinear springs to which the collapse mechanisms were applied.
Effects of Engine Control Variables on Exhaust Gas Temperature and Stability during Cranking Operation of an SI Engine
Cho, Yong-Seok ; An, Jae-Won ; Park, Young-Joon ; Kim, Duk-Sang ; Lee, Seang-Wock ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 64~70
Raising exhaust gas temperature during cold-start period is very crucial to improve emission performance of SI engines because it enhances the performance of catalyst in the early stage of engine start. In this study, control variables such as ignition timing, idle speed actuator(ISA) opening and fuel injection duration were extensively investigated to analyze variations in exhaust gas temperature and engine stability during cranking period. Experimental results showed that spark timing affected engine stability and exhaust gas temperature but the effects were small. On the other hand, shortened injection duration and increased ISA opening led to a significant increase in exhaust gas temperature. Under such conditions, increase in cranking time was also observed, showing that it becomes harder to start the engine. Based on these observations, a pseudo fuel-air ratio, defined as a ratio of fuel injection time to degree of ISA opening, was introduced to analyze the experimental results. In general, decrease in pseudo fuel-air ratio raised exhaust gas temperature with the cost of stable and fast cranking. On the contrary, an optimal range of the pseudo fuel-air ratio was found to be between 0.3 to 0.5 where higher exhaust gas temperatures can be obtained without sacrificing the engine stability.
Development of a Safe Driving Management System
Cho, Jun-Hee ; Lee, Woon-Sung ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 71~77
Dangerous driving is a major cause of traffic accidents in Korea. It becomes more serious for commercial vehicles due to higher fatality rates. The Safe Driving Management System (SDMS), developed in this research, is a comprehensive solution that monitors and stores driving conditions of vehicles, detects dangerous driving situations, and analyzes the results in real time. The Safe Driving Management System consists of a vehicle movement information controller, a dangerous driving detection algorithm and a vehicle movement data report and analysis program. The dangerous driving detection algorithm detects and classifies dangerous driving conditions into representative cases such as sudden acceleration, sudden braking, sudden lane change, and sudden turning. Both computer simulation and vehicle test have been conducted to develop and verify the algorithm. The Safe Driving Management System has been implemented on commercial buses to verify its reliability and objectivity. It is expected that the system can contribute to prevention of traffic accidents, systemization of safe driving management and reduction of commercial vehicle operation costs.
A Detailed Examination of Various Porous Media Flow Models for Collection Efficiency and Pressure Drop of Diesel Particulate Filter
Jung, Seung-Chai ; Yoon, Woong-Sup ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 78~88
In the present study a detailed examination of various porous media models for predicting filtration efficiency and pressure drop of diesel particulate filter (DPF), such as sphere-in-cell and constricted tube models, are attempted. In order for demonstrating their validities of correct estimation on permeability, geometry of property configurations common in commercial cordierite DPFs are correlated to the porous media flow models, and validations of predicted filtration efficiencies due to the use of different unit collectors are made with experiments. The result shows that the porosity, pore size and permeability of cordierite DPF can be successfully correlated by Kuwabara flow field with correction factor of 0.6. The unit collector efficiency predicted by sphere-in-cell model agrees very well with measurements in accumulation mode, whereas that by constricted tube model with significant prediction error.
Crash FE Analysis of Front Side Assembly for Reverse Engineering
Kim, Yong-Woo ; Kim, Jeong-Ho ; Jeong, Kyung-Shin ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 89~98
Crashworthiness design is of special interest in automotive industry and in the transportation safety field to ensure the vehicle structural integrity and more importantly the occupant safety in the event of the crash. Front side assembly is one of the most important energy absorbing components in relating to the crashworthiness design of vehicle. The structure and shape of the front side assemblies are different depending on automakers. Thus, it is not easy to grab an insight on designer's intention when you glance at a new front side member without experiences. In this paper, we have performed the explicit nonlinear dynamic finite element analysis on the front side assembly of a passenger car to identify the mechanical roles of each part of the assembly and to enhance the absorbing energy from the viewpoint of reverse engineering.
A Study on the New 3-D Angular Flow Index for Evaluation of In-Cylinder Bulk Flow Characteristics of the Air Induced by Variable Induction System
Yun, Jeong-Eui ; Nam, Hyeon-Sik ; Kim, Myung-Hwan ; Min, Sun-Ki ; Sim, Dae-Gon ; Park, Pyeong-Wan ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 99~105
It is very important to clarify the 3-D angular flow characteristics of in-cylinder bulk motion in the developing process of variable induction system. In-cylinder flow induced by variable induction system is very complex, so we can not describe the in-cylinder bulk flow characteristics using the conventional swirl or tumble coefficient. In this study, we introduced the new 3-D angular flow index, angular flow coefficient(
), for in-cylinder bulk flow characteristics. And also, to confirm the index, we carried out the steady flow rig test for intake port of test engine varying valve lift on the test matrix.
A Study on Light Weight Hood Design for Pedestrian Safety
Lee, Won-Bae ; Kang, Sung-Jong ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 106~115
In this study, first, child headform model was built up, satisfying requirement in the headform validation test. Also, for decreasing both acceleration peak and deformation, a new hood with dome shaped forming in inner panel was investigated. Next, headform impact, complying with draft of EEVC W/G 17, on the central portion of the newly proposed hood were simulated for a steel hood and three aluminum hoods with different thickness for examining the material and thickness effect on HIC value and inner panel deformation. The analysis results explained that aluminum hoods with dome shaped forming in inner panel were highly promising not only for meeting headform safety regulations but also for leading to weight savings. Finally, hood edge design technology in order to reduce pedestrian injury due to the high stiffness of beam type edge and the rigid support, was discussed. Various types of the foam filled edge were designed and their headform safety performance were evaluated. The edge structure with foam filled in upper one third of section exhibited excellent results.
A Study on Temporal Measurement of Size and Concentration for Soot Aggregates among Exhaust Emissions in Diesel Engines
Bae, Myung-Whan ; Kamimoto, Takeyuki ; Bae, Chang-Hwan ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 116~124
An optical method to measure the size and number density of soot aggregates in diesel exhaust has been proposed in this study. Two laser beams in co-axial alignment transmit a soot loaded exhaust gas flow, and the transmittance at each wavelength is detected by a photo diode simultaneously. The volume equivalent diameter and number density of soot aggregates in the optical path can be theoretically given by the transmittance values measured at two wavelengths. A test conducted by a single cylinder, 4 cycle, small and DI diesel engine shows that the temporal variations of the size and number density of soot aggregates in the diesel exhaust can be measured by the proposed method at a transient mode operation. It is found that the volume equivalent diameter varied temporally from 70 to 110 nm during the period that high soot concentration is observed. One can also conclude that the optical length longer than 1 m in the dynamic range regarding this method is preferable for measuring soot concentration at the level of
The Invention of New Electro-Mechanical Brake Calipers Utilizing Patent Analysis Results
Han, In-Hwan ; Park, Sang-Il ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 125~132
Within the framework of brake-by-wire technology, this paper presents five types of novel models of electro-mechanical disk brake calipers with self-servo mechanism which provides self-servo effect of boosting a friction force generated between the brake pad and the rotor disk surface. The models have been developed utilizing patent map analysis results of previous invents of electro-mechanical brake calipers. The feasibility of the developed motor-driven brake caliper models have been validated through the dynamic simulation analysis. Among the developed models, the caliper mechanism with separated pressure plate was designed especially in detail and was made as a pilot. The pilot caliper has been installed on the simple test bed constructed with domestic passenger car brake components, and its function and effectiveness have been validated through several types of experimental tests.
CAE Procedure of Engine Balance Shaft Housing for Prediction of Durability
Choi, Hang-Jip ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 133~138
The balance shaft housing in the recent engines tends to have the high cycle fatigue crack caused by increased engine power. In this paper, a CAE procedure is introduced to predict the durability of the balance shaft housing. The procedure is performed through two analysis steps. In the first step, the multibody dynamic simulation is used to obtain more accurate loading boundary conditions applied to the finite element model for the following step. Next, the finite element analysis is performed to predict the durability of the balance shaft housing through the calculation of the safety factor. Through this CAE procedure, the revised balance shaft housing was developed to improve the durability. And the durability of the housing was confirmed experimentally.
Thermal Fatigue Life Prediction of Engine Exhaust Manifold
Choi, Bok-Lok ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 139~145
This paper presents the low cycle thermal fatigue of the engine exhaust manifold subject to thermomechanical cyclic loadings. The analysis includes the FE model of the exhaust system, temperature dependent material properties, and thermal loadings. The result shows that at an elevated temperature, large compressive plastic deformations are generated, and at a cold condition, tensile stresses are remained in several critical zones of the exhaust manifold. From the repetitions of thermal shock cycles, plastic strain ranges could be estimated by the stabilized stress-strain hysteresis loops. The method was applied to assess the low cycle thermal fatigue for the engine exhaust manifold. It shows a good agreement between numerical and experimental results.
Structural Design of an Automotive Door Using the Kriging Models
Lee, Kwon-Hee ; Bang, Il-Kwon ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 146~153
Weight reduction for automobile components has been sought to achieve fuel efficiency and energy conservation. There are two approaches in reducing their weights. One is by using material lighter than steel, and the other is by redesigning their structures. The latter has been performed by adopting hydroforming, tailor weled blank, optimization, etc. In this research, the kriging approximation method and simulated annealing algorithm are applied to the design of a front door made by TWB (Tailor Welded Blank) technology. The design variables are set up as the thicknesses of parts and the positions of parting lines. A thickness set considered as a design variable of each part is not arbitrarily determined but selected from standard products, so it is a discrete set. This research presents the discrete and continuous structural optimization method for an automotive door design.
A Study of Frictional Contact Vibration Influence on Hot Spot in Automotive Disk Brake
Cho, Ho-Joon ; Kim, Myoung-Gu ; Cho, Chong-Du ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 154~161
Hot spot phenomenon that occurs, during judder vibration, is locally concentrated heat due to friction between brake disk and pad. It is important to understand the reason behind hot spot phenomenon, for reduction of judder vibration. In this experimental study, experiments were performed in accordance with rotation speed of brake disk, pressure of master cylinder and pad length for achieving different aspects of hot spot phenomenon. Temperature distribution of hot spot was obtained by using the infrared camera. As the hot spot occurred, vibration was measured and frequency analysis was performed. Finite element analysis of thermal deformation of disk was performed by using temperature distribution that was achieved by experimental results. And mode shapes of disk was analyzed by finite element analysis and compared with experimental results. It was observed that the excitation frequency band of frictional contact and frictional force mainly affects the hot spot phenomenon.
The Effects of Engine Speed and Load of the Partial Premixed Diesel Compressed Ignition Engine Applied with the Split Injection Method on Exhaust Gas and IMEP Characteristics
Kang, Jeong-Ho ; Lee, Sung-Man ; Chung, Jae-Woo ; Kang, Woo ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 162~170
Currently, due to the serious world-wide air pollution by substances emitted from vehicles, emission control is enforced more firmly and it is expected that the regulation requirements for emission will become more severe. Anew concept combustion technology that can reduce the NOx and PM in relation to combustion is urgently required. Due to such social requirement, technologically advanced countries are making efforts to develop an environment-friendly vehicle engine at the nation-wide level in order to respond to the reinforced emission control. As a core combustion technology among new combustion technologies for the next generation engine, the homogeneous charge compression ignition (HCCI) is expanding its application range by adopting multiple combustion mode, catalyst, direct fuel injection and partially premixed combustion. This study used a 2-staged injection method in order to apply the HCCI combustion method without significantly altering engine specifications in the aspect of multiple combustion mode and practicality by referring to the results of studies on the HCCI engine. And it is investigated that the effects of the engine rpm and load(or A/F) to emission characteristics.
Dynamic Tensile Characteristics of the High Strength Steel Sheet for an Auto-body
Kim, Seok-Bong ; Huh, Hoon ; Shin, Chirl-Soo ; Kim, Hyo-Kun ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 171~176
An important challenging issue in the automotive industry is the light-weight, safe design and enhancement of crash response of an auto-body structures. These objectives lead to increasing adoption of high strength steel sheet for inner and outer auto-body members. This paper evaluates the dynamic tensile characteristics of high strength steel sheets, HS45R, TRIP60, DP60 and DP100, along the rolling direction and transverse direction. Static tensile tests were carried out at the strain rate of 0.003/sec using the static tensile machine (Instron 5583). Dynamic tensile tests were carried out at the range of strain rate from 0.1/sec to 200/sec using a high speed material testing machine developed. The tensile tests acquire stress-strain relation and strain rate sensitivity of each material. The experimental results show two important aspects for high strength steels: the flow stress increases as strain rate increases; the strain hardening decreases as the tensile stress increases. The experiments also produce interesting results that the elongation does not decrease even when the strain rate increases.
A Study on the Measurement of Temperature and Soot for Diffusion Flame in a Visualized D.I Diesel Engine Using the Two-color Method
Han, Yong-Taek ; Lee, Ki-Hyung ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 177~185
The temperature and soot of the visualized diesel engine's turbulent flow of flame was qualitatively measured. In combustion chamber, in order to judge the affect that the swirl has on the in-cylinder's current, was used two different heads with different values. Using the high speed camera, and the results were analyzed using the heat release rate produced by the pressure sensor. In order to measure the temperature and soot of the turbulent flames like that of the diesel flames two color methods were used temperature and the soot of the flames according to the conditions through analyzing the two wavelengths of the flames. It was possible to measure the highest temperature of the non-swirl head visualized engine which is approximately 2400K, and that swirl head engine managed up to 2100K. With respect to the visualized diesel engine soot, we got the grasp of the KL factor which bears the qualitative information of soot. This study is dedicated to suggesting the possibility of measuring not only the temperature but also soot of the diffusion flame of the diesel engine turbulent flames through such method.
Numerical Study on the Characteristics of Pressure Pulsations according to Design Factors of Fuel Rail with Self Damping Effect
Heo, Hyung-Seok ; Bae, Suk-Jung ; Song, Kyung-Suk ; Kim, Bo-Kyoum ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 186~192
In general, pulsation damper is installed in fuel rail for conventional MPI engine to decrease undesirable noise in vehicle cabin room. However, pulsation damper is so expensive that there are prevailing studies to reduce fuel pressure pulsations with integrated damping effect. This paper is one of basic studies for development of fuel rail to abate pulsations with self-damping effect. Primarily, the pressure pulsation characteristics was investigated with aspect ratio of cross section, wall thickness, and materials of fuel rail. A high aspect ratio or thin wall was found to absorb the pressure pulsations effectively. But volume effects on the fuel pressure pulsation reductions were not especially significant than cross section effects because volume increment rate is larger than pressure pulsation reduction rate. The fuel rail made of aluminum is effective for reduction of pressure pulsation than that of low-carbon steel. Pressure change period increases on the basis of same lengths of supply line and fuel rail as the volume is enlarged and/or the thickness of wall is thinned.
The Effect of Fuel Injection Timing on Combustion and Power Characteristics in a DI CNG Engine
Kang, Jeong-Ho ; Yoon, Soo-Han ; Lee, Joong-Soon ; Park, Jong-Sang ; Ha, Jong-Yul ;
Transactions of the Korean Society of Automotive Engineers, volume 15, issue 1, 2007, Pages 193~200
Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its lower harmful emissions, including
, and high thermal efficiency. In particular, natural gas is seen as an alternative fuel for heavy-duty Diesel Engines because of the lower resulting emissions of PM,
. Almost all CNG vehicles use the PFI-type Engine. However, PFI-type CNG Engines have a lower brake horse power, because of reduced volumetric efficiency and lower burning speed. This is a result of gaseous charge and the time losses increase as compared with the DI-type. This study was conducted to investigate the effect of injection conditions (early injection mode, late injection mode) on the combustion phenomena and performances in the or CNG Engine. A DI Diesel Engine with the same specifications used in a previous study was modified to a DI CNG Engine, and injection pressure was constantly kept at 60bar by a two-stage pressure-reducing type regulator. In this study, excess air ratios were varied from 1.0 to the lean limit, at the load conditions 50% throttle open rate and 1700rpm. The combustion characteristics of the or CNG Engine - such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions - were investigated. Through this method, it was possible to verify that the combustion duration, the lean limit and the emissions were improved by control of injection timing and the stratified mixture conditions. And combustion duration is affected by not only excess air ratio, injection timing and position of piston but gas flow condition.