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221.
D. García-Pozuelo Ramos A. Gauchía B. L. Boada V. Díaz 《International Journal of Automotive Technology》2010,11(5):691-699
Vehicle systems such as the steering, brakes and suspension greatly influence vehicle safety. Therefore, these systems must
be inspected to guarantee that they are functioning correctly and to certify that the vehicle is functioning at a satisfactory
safety level. In disc brakes, warping is one of the principal reasons for vibrations and noise, and it contributes to diminished
brake efficiency. Currently, the International Motor Vehicle Inspection Committee (CITA) demands disc brake warping inspections
occur during periodic motor vehicle inspections (PMVIs); however, the procedure to carry out this inspection is not well defined.
In this investigation, the warping phenomenon has been analyzed, and a new inspection procedure is proposed. 相似文献
222.
D. K. Park C. D. Jang S. B. Lee S. J. Heo H. J. Yim M. S. Kim 《International Journal of Automotive Technology》2010,11(4):489-494
This paper presents a design technique to optimize the shape of a vehicle bumper beam that satisfies both the safety requirements
for a front rigid-wall impact and the regulations protecting pedestrians from lower leg injuries caused by bumper impacts.
An intermediate response surface modeling (IRSM) technique was introduced to approximate the non-linear force-displacement
curves obtained from the front impact analysis of a vehicle bumper. The accuracy of the IRSM model was tested by comparing
its results with those of the non-linear finite element analysis. The maximum displacement error between the two models did
not exceed 3%. Using pedestrian impact analyses based on the experimental arrangement of the Plackett-Burman design, the approximate
functions describing the response values acting on the lower legs were calculated. The shape of the bumper beam was optimized
by integrating the IRSM with the force-displacement model and the approximate functions on lower leg impact. The optimization
results satisfied safety regulations on the maximum allowable displacement of the vehicle bumper, and also the regulations
protecting pedestrians from lower leg injuries caused by bumper impacts. 相似文献
223.
S. B. Han Y. H. Chang E. Y. Lee Y. J. Chung B. Suh 《International Journal of Automotive Technology》2010,11(1):105-110
Hybrids combine a combustion engine with an electric motor and battery. The two technologies can be combined to reduce fuel
consumption and exhaust emissions. This paper presents the concept of hybrid electric vehicles (HEVs) applied to truck or
van vehicles with diesel engines. The simulation results from the advanced vehicle simulator (ADVISOR) demonstrate that the
required power may be properly shared between the internal combustion engine and electric motor. The simulation can also be
used to prove that the technique is useful for improvements in driving performance; additionally, the technique is suitable
for hybrid electric vehicles, allowing for good fuel economy and low emissions performance. 相似文献
224.
B. H. Lee J. H. Song Y. J. Chang C. H. Jeon 《International Journal of Automotive Technology》2010,11(6):783-791
The diesel combustion process is highly dependent on fuel injection parameters, and understanding fuel spray development is
essential for proper control of the process. One of the critical factors for controlling the rate of mixing of fuel and air
is the number of injector holes in a diesel engine. This study was intended to explore the behavior of the formation of spray
mixtures, combustion, and emissions as a function of the number of injector hole changes; from this work, we propose an optimal
number of holes for superior emissions and engine performance in diesel engine applications. The results show that increasing
the number of holes significantly influences evaporation, atomization, and combustion. However, when the number of holes exceeds
a certain threshold, there is an adverse effect on combustion and emissions due to a lack of the air entrainment required
for the achievement of a stoichiometric mixture. 相似文献
225.
Active coolant control strategies in automotive engines 总被引:1,自引:0,他引:1
K. B. Kim K. W. Choi K. H. Lee K. S. Lee 《International Journal of Automotive Technology》2010,11(6):767-772
The coolant flow rate in conventional cooling systems in automotive engines is subject to the mechanical water pump speed,
and high efficiency in terms of fuel economy and exhaust emission is not possible given this limitation. A new technology
must be developed for engine cooling systems. The electronic water pump is used as a substitute for the mechanical water pump
in new engine cooling systems. The new cooling system provides more flexible control of the coolant flow rate and engine temperature,
which previously relied strongly on engine driving conditions such as load and speed. In this study, the feasibility of two
new cooling strategies was investigated using a simulation model that was validated with temperatures measured in a diesel
engine. Results revealed that active coolant control using an electronic water pump and valves substantially contributed to
a reduction of coolant warm-up time during cold engine starts. Harmful emissions and fuel consumption are expected to decrease
as a result of a reduction in warm-up time. 相似文献
226.
T. -Y. Koo B. -Y. Kim H. -J. Shin Y. -T. Son S. -W. Kim M. -W. Suh 《International Journal of Automotive Technology》2010,11(5):743-749
Driving simulators are useful tools that can be used not only to test the components of future cars, but also to evaluate
the telematics service and HMI (Human-Machine Interface). However, driving simulators that are currently available cannot
be implemented to test and evaluate a real commercial telematics service system because the GPS (Global Positioning System),
which contains basic functional support for the telematics module, does not work in the VR (virtual reality) environment.
A driving simulator, together with the GPS simulator, can be used to study the HMI to evaluate commercial CNS (Car Navigation
Systems). In this paper, Sungkyunkwan University Driving Simulator (SKUD) is developed with a GPS simulator that is able to
emulate GPS satellite signals and includes the NMEA-0183 protocol and RS232C communication standards. Furthermore, using the
SKUD, the HMI of the real commercial CNS could be investigated with driver workload assessment methods. 相似文献
227.
H. S. Kook S. R. Shin K. D. Ih D. B. Kim D. H. Yu 《International Journal of Automotive Technology》2009,10(1):55-63
The large-scale shear flows over the sunroof opening of a mid-sized SUV measured using a PIV system were investigated. The
shear flows were measured for five different cases of deflector protrusion (one case was the baseline test without deflector)
at two different free stream flow velocities below the critical velocity where the buffeting noise level reached a maximum.
The structures of the shear flows were observed to differ, apparently depending on whether the radiated buffeting noise is
relatively strong or not. For strongly buffeting experimental cases, the momentum thicknesses of the shear layers were observed
to grow rapidly and saturated at a station near the downstream edge of the sunroof opening, where the saturation of the transverse
velocity fluctuations was also observed, and where the vortex coalescence process was presumably completed. On the other hand,
no discrete large-scale vortex structures were observed for none-buffeting or weakly buffeting cases. Streamwise growth of
the velocity fluctuations was found to be well predicted by a linear hydrodynamic instability analysis for the strongly buffeting
cases. Numerical results obtained from a linear inviscid instability analysis using a hyperbolic tangent mean velocity profile
were used to calculate the amplification factors with the initial momentum thickness and the streamwise fluctuation wavenumber.
The shear flows were found to form large-scale discrete vortices when the linear inviscid amplification factors exceeded a
threshold amplification factor. 相似文献
228.
G. S. Jung Y. H. Sung B. C. Choi M. T. Lim 《International Journal of Automotive Technology》2009,10(1):1-7
Compression ignition of homogeneous charges in internal combustion (IC) engines is expected to offer high efficiency of DI
diesel engines without high levels of NOx and particulate emissions. This study is intended to find ways of extending the
rich limit of HCCI operation, one of the problems yet to be overcome. Exhaust emissions characteristics are also explored
through analyses of the combustion products. DME fuel, either mixed with air before induction or directly injected into the
combustion chamber of a rapid compression and expansion machine, is compressed to ignite under various conditions of compression
ratio, equivalence ratio, and injection timing. The characteristics of the resulting combustion and exhaust emissions are
discussed in terms of the rate of heat release computed from the measured pressure, and the concentrations of THC, CO, and
NOx are measured by FT-IR and CLD. The experimental data to date show that operation without knock is possible with mixtures
of higher equivalence ratio when DME is directly injected rather than when it is inducted in the form of a perfectly homogeneous
fuel-air mixture. Although fuel injected early in the compression stroke promotes homogeneity of the DME-air mixture in the
cylinder, it causes the mixture to ignite too early to secure good thermal efficiency and knock-free operation at high loads.
Low temperature reactions occur at about 660K regardless of the fueling methods, fuel injection timing and equivalence ratio.
The main components of hydrocarbon emissions turned out to be unburned fuel (DME), formaldehyde and methane. 相似文献
229.
S. S. Merola P. Sementa C. Tornatore B. M. Vaglieco 《International Journal of Automotive Technology》2009,10(5):545-553
A low-cost solution based on fuel injection strategies was investigated to optimize the combustion process in a boosted port
fuel injection spark ignition (PFI SI) engine. The goal was to reduce the fuel consumption and pollutant emissions while maintaining
performance. The effect of fuel injection was analyzed for the closed and open valve conditions, and the multiple injection
strategies (MIS) based on double and triple fuel injection in the open-valve condition. The tests were performed on an optical
accessible single-cylinder PFI SI engine equipped with an external boost device. The engine was operated at full load and
with a stoichiometric ratio equivalent to that of commercial gasolines. Optical techniques based on 2D-digital imaging were
used to follow the flame propagation from the flame kernel to late combustion phase. In particular, the diffusion-controlled
flames near the valves and cylinder walls, due to fuel deposition, were studied. In these conditions, the presence of soot
was measured by two-color pyrometry, and correlated with engine parameters and exhaust emissions measured by conventional
methods. The open valve fuel injection strategies demonstrated better combustion process efficiency than the closed ones.
They provided very low soot levels in the combustion chamber and engine exhaust, and a reduction in specific fuel consumption.
The multiple injection strategies proved to be the best solution in terms of performance, soot concentration, and fuel consumption. 相似文献
230.
Y. T. Son B. Y. Kim K. J. Park H. Y. Lee H. J. Kim M. W. Suh 《International Journal of Automotive Technology》2009,10(5):635-644
To guarantee the efficiency of maintenance strategies for a complex structure, safety and cost limitations must be considered.
This research introduces RCM-based (Reliability Centered Maintenance) life cycle optimization for reasonable maintenance.
The design variable is the reliability of each part, which consists of a complex structure, while the objective is to minimize
the total cost function in order to maintain the system within the desired system reliability. This research constructs the
cost function that can reflect the current operating condition and maintenance characteristics of individual parts by generating
essential cost factors. To identify the optimal reliability of each component in a system, this paper uses a Neuro-Evolutionary
technique. Additionally, this research analyzes the reliability growth of a system by using the AMSAA (Army Material Systems
Analysis Activity) model to estimate the failure rate of each part. The MTBF (Mean Time Between Failure) and the failure rate
of the whole system, which is responding to the individual parts, are estimated based on the history data by using neural
networks. Finally, this paper presents the optimal life cycle of a complex structure by applying the optimal reliability and
the estimated MTBF to the RAMS (Reliability, Availability, Maintainability, and Safety) algorithm. 相似文献