排序方式: 共有223条查询结果,搜索用时 15 毫秒
121.
M. H. Lee H. M. Lee K. S. Lee S. K. Ha J. I. Bae J. H. Park H. G. Park H. J. Choi H. H. Chun 《International Journal of Automotive Technology》2011,12(5):733-744
In this paper, a hardware-in-the-loop simulation (HILS) system was developed before the development of an electric power steering
(EPS) system in a vehicle. This study was focused on the establishment of the HILS system. Driving conditions are simulated
with the HILS system. The actual steering input parameters are confirmed on the monitor while driving the HILS system. The
steering forces observed in the simulation with the developed HILS system are similar to those in real vehicle tests. The
developed HILS system can be applied in the development of various types of EPS systems. 相似文献
122.
An experiment was conducted to characterize the effects of SOF on EGR cooler fouling. A removable singletube test rig combined with a soot generator was developed to represent an EGR cooler and diesel exhaust gas. The use of a soot generator, which controlled the size and concentration of soot particles, enabled independent variables to be completely controlled. Either n-dodecane or diesel lube oil as substitute SOFs were vaporized and injected into the test rig to evaluate their effects on the growth of PM deposits and the degradation performance of the EGR cooler. Coolant temperature, which seemed to be associated with SOF content, was chosen as an independent variable, and PM deposit mass per unit area and the effectiveness drop versus time increased as the coolant temperature decreased. The PM deposit mass per unit area and effectiveness drop had maximum values at a coolant temperature of 40°C for every n-dodecane injection rate. For substitute SOFs tested in this experiment, the deposit mass increased when either n-dodecane or diesel lube oil was injected, but the effect of lube oil was more significant. Diesel lube oil seemed to have a stronger effect on the reduction of thermal conductivity by filling pores in the deposits. When diesel lube oil was injected, the deposit mass per unit area increased 127% compared to dry soot without injection. The effectiveness drop after 10 hours increased only 12.5%. 相似文献
123.
S. W. Lee Y. S. Cho W. C. Choi J. H. Lee Y. J. Park 《International Journal of Automotive Technology》2012,13(7):1149-1157
This study aims to investigate the combustion characteristics of mixed fuel of liquefied propane gas (LPG) and biodiesel under compression ignition (CI) in an effort to develop highly efficient and environmentally friendly mixed fuelbased CI engines. Although LPG fuel is known to be eco-friendly due to its low CO2 emission, LPG has not yet been widely applied for highly efficient CI engines because of its low cetane number and is usually mixed with other types of CI-friendly fuels. In this study, a number of experiments were prepared with a constant volume chamber (CVC) setup to understand the fundamental combustion characteristics of mixed fuel with LPG and biodiesel in two weight-based ratios and exhaust gas recirculation (EGR) conditions. The results from the current investigations verify the applicability of mixed fuel of LPG and biodiesel in CI engines with a carefully designed combustion control strategy that maximizes the benefits of the mixed fuel. Based on the results of this study, ignition is improved by increasing the cetane value by using higher blending ratios of biodiesel. As the blending ratios of biodiesel increased, CO and HC decreased and CO2 and NOx increases. 相似文献
124.
H. S. Heo S. J. Bae H. K. Lee K. S. Park 《International Journal of Automotive Technology》2012,13(2):167-173
In a conventional MPI engine, a pulsation damper is usually mounted on the fuel rail to diminish undesirable noise in the
vehicle cabin room; however, pulsation dampers are quite expensive. Therefore, several studies have focused on reducing fuel
pressure pulsation by increasing the self-damping characteristics of the fuel rail. This paper details the development of
a fuel rail that reduces pulsation using a self-damping effect. Using an oil hammer simulation technique, pressure pulsation
characteristics were investigated with respect to the aspect ratio of the cross-section, wall thickness, and fuel rail material.
Increasing the aspect ratio and decreasing the wall thickness efficiently reduced the pressure pulsation. In addition, the
pressure pulsation characteristics were investigated with respect to the resonant engine speed and injection period. These
simulated data can be used to reduce the pressure pulsation peak and to avoid the resonant point in the design stage during
the development of a fuel rail. 相似文献
125.
C. H. Zheng Y. I. Park W. S. Lim S. W. Cha 《International Journal of Automotive Technology》2012,13(3):517-522
The fuel economy of a fuel cell hybrid vehicle (FCHV) depends on its power management strategy because the strategy determines
the power split between the power sources. Several types of power management strategies have been developed to improve the
fuel economy of FCHVs. This paper proposes an optimal control scheme based on the Minimum Principle. This optimal control
provides the necessary optimality conditions that minimize the fuel consumption and optimize the power distribution between
the fuel cell system (FCS) and the battery during driving. In this optimal control, the final battery state of charge (SOC)
and the fuel consumption have an approximately proportional relationship. This relationship is expressed by a linear line,
and this line is defined as the optimal line in this research. The optimal lines for different vehicle masses and different
driving cycles are obtained and compared. This research presents a new method of fuel economy evaluation. The fuel economy
of other power management strategies can be evaluated based on the optimal lines. A rule-based power management strategy is
introduced, and its fuel economy is evaluated by the optimal line. 相似文献
126.
We investigated the effects of the fuel injection timing — both for early and late injection — in conjunction with the throttle
opening ratio on the fuel-air mixing characteristics, engine power, combustion stability and emission characteristics of a
DI CNG spark engine and control system that had been modified and designed according to the author’s original idea. We verified
that the combustion characteristics were affected by the fuel injection timing and that the engine conditions were affected
by the throttle opening ratios and the rpm. The combustion characteristics were greatly improved for a complete open throttle
ratio with an early injection timing and for a partial throttle ratio with a late injection timing. The combustion duration
was governed by the duration of flame propagation in late injection timing scenarios and by the duration of early flame development
in cases of early injection timing. As the result, the combustion duration is shortened, the lean limit is improved, the air-fuel
mixing conditions are controlled, and the emissions are reduced through control of the fuel injection timing and vary according
to ratio of the throttle opening. 相似文献
127.
R. A. Sindhu M. K. Park S. J. Lee K. D. Lee 《International Journal of Automotive Technology》2010,11(6):857-863
This study was conducted to determine whether the different residual stresses caused by different welding speeds affect the
static and fatigue strength of laser-welded lap joints. Residual stresses in STS301L laser-welded lap joints of different
thicknesses under two laser-welding speed conditions, 4.1 m/min and 5.1 m/min, were evaluated with the incremental hole-drilling
strain gage method at the middle of the heat-affected zone (HAZ). Then, static and fatigue tests were performed. The results
show that higher static and fatigue strengths were obtained from the specimens welded with a 4.1 m/min welding speed than
from the specimens welded at 5.1 m/min. The main difference was due to the compressive principal residual stress magnitude
and its orientation near the HAZ. Also, the micro-hardness profile along the failure interface was measured to verify the
static and fatigue failure behavior. 相似文献
128.
In this paper, a numerical procedure to estimate the performance of the high power pretensioner used in the seatbelt of a
passenger vehicle is presented. The data on the gas explosion pressure in a 10-cc volume and the data on the displacement
of the rack according to time were applied to the numerical procedure. The procedure was implemented using MATLAB. The testing
device, which met the automobile industry standards, was created. Experiments were carried out seven times under the same
conditions, and the mean values of the web retraction and belt load were used as the representative data. By comparing the
simulation results to the test results, the numerical procedure presented in this paper was verified. 相似文献
129.
Until recently, passenger cars have primarily interested in pedestrian protection performance. Nowadays, however, it is important
for a sport-utility vehicle (SUV) to meet the bumper system standards for pedestrian safety. For a SUV bumper system, there
are some difficulties in attaining a high level of pedestrian performance for the lower legform. An SUV has a high bumper
position from the ground level, and the bumper approach angle must also be secured, which has an effect on car insurance fees.
Due to these reasons, it is difficult to meet the pedestrian performance of the lower legform for an SUV. In this paper, a
comparative study was performed on various SUV bumper systems, and a concept model for a SUV bumper system was developed,
which is expected to meet the pedestrian performance by using the Pugh method. The design control factors were defined to
affect the bumper pedestrian performance through the experiences of tests and analyses. For the noise factor to affect the
pedestrian performance, the deviation of the impactor position was selected at the moment of impact. The design control factors
were optimized by using the Taguchi optimization technique. For the Taguchi method, an L18 orthogonal array table of design
control factors was used in the optimization process. Particularly, for the optimization of the bumper corner region, an optimization
analysis was performed three times to meet pedestrian performance. Based on the results of the Taguchi optimization method,
the sensitivity of the bumper design parameters was studied, and a new SUV bumper system is proposed that satisfies the pedestrian
performance of the lower legform. The optimized bumper system should obtain a full Euro-NCAP score of 6 points for the bumper
test. The pedestrian performance of the optimized bumper system is validated by using a CAE (Computer Aided Engineering) analysis,
which has been proven to be in accurate. A comparison between the test and analysis results is shown for the validation of
accuracy. By using the optimized bumper system, the tests and development costs of a bumper can be reduced. 相似文献
130.
社区步行通达性对独栋住宅房价的效益评估--美国德克萨斯州奥斯丁市空间特征分析 总被引:2,自引:0,他引:2
通过分析美国德克萨斯州奥斯丁市2010—2012年独栋住宅的销售价格,以街道智慧步行指数(Street Smart Walk Score)和人行道密度(Sidewalk Density)作为衡量指标,研究社区步行通达性对房价的影响。使用Cliff-Ord空间特征模型(即广义空间模型,General Spatial Model,或者SAC)控制空间自相关影响。结果表明:在依赖小汽车的社区通过增加设施可达性来提升步行通达性的举措并不能提高房价;增加人行道也只能最小限度地提高房价。投资社区便利设施和人行道对适宜步行社区的房价提升效果比依赖小汽车的社区显著。 相似文献