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排序方式: 共有1705条查询结果,搜索用时 78 毫秒
861.
D. -H. Shin B. -H. Lee J. -B. Jeong H. -S. Song H. -J. Kim 《International Journal of Automotive Technology》2011,12(1):125-130
Hybrid electric vehicles (HEV) utilize electric power and a mechanical engine for propulsion; therefore, the performance of
HEVs is directly influenced by the characteristics of the energy storage system (ESS). The ESS for an HEV generally requires
high power performance, long cycle life, reliability and cost effectiveness; thus, a hybrid energy storage system (HESS) that
combines different types of storage devices has been considered to fulfill both performance and cost requirements. To improve
the operating efficiency and cycle life of a HESS, an advanced dynamic control regime in which pertinent storage devices in
the HESS can be selectively operated based on their status is presented. Verification tests were performed to confirm the
degree of improvement in energy efficiency. In this paper, an advanced HESS with a battery management system (BMS) that includes
an optimal switching control function based on the estimated state of charge (SOC) is presented and verified. 相似文献
862.
There has been recent interest in intelligent vehicle technologies, such as advanced driver assistance systems (ADASs) or
in-vehicle information systems (IVISs), that offer a significant enhancement of safety and convenience to drivers and passengers.
However, the use of ADAS- and IVIS-based information devices may increase driver distraction and workload, which in turn can
increase the chance of traffic accidents. The number of traffic accidents involving older drivers that are due to distraction,
misjudgment, and delayed detection of danger, all of which are related to the drivers’ declining physical and cognitive capabilities,
has increased. Because the death rate in traffic accidents is higher when older drivers are involved, finding ways to reduce
the distraction and workload of older drivers is important. This paper generalizes driver information device operations and
assesses the workload while driving by means of experiments involving 40 drivers in real cars under actual road conditions.
Five driving tasks (manual only, manual primarily, visual only, visual primarily, and visual-manual) and three age groups
(younger (20–29 years of age), middle-aged (40–49 years of age), and older (60–69 years of age)) were considered in investigating
the effect of age-related workload difference. Data were collected from 40 drivers who drove in a real car under actual road
conditions. The experimental results showed that age influences driver workload while performing in-vehicle tasks. 相似文献
863.
This paper presents the design optimization process of a short fiber-reinforced plastic armrest frame to minimize its weight
by replacing the steel frame with a plastic frame. The analysis was carried out with the equivalent mechanical model and design
of experiment (DOE) method. Instead of considering the whole structure, it is divided into three simpler regions to reduce
the complexity of the problem through examining its structural characteristics and load conditions. The maximum stress and
deflection of the regions that carry the normal load are calculated by the analytical mathematical form derived from an equivalent
model. The other regions loaded by contact stress are handled by FEM (finite element method), the DOE method, and the RSM
(response surface model). To optimize the design variables in both cases, the object functions derived from these calculations
are solved with a CAE (computer aided engineering) tool. This method clearly shows the mechanical and mathematical representation
of structural optimization and reduces the computing costs. After design optimization, the weight of the optimum plastic-based
armrest frame is reduced by about 18% compared to the initial design of a plastic frame and is decreased by 50% in comparison
with the steel frame. Some prototypical armrest frames were also made by injection molding and tested. The research results
fulfilled all of the design requirements. 相似文献
864.
S. J. Kang M. F. Kader Y. D. Jun K. B. Lee 《International Journal of Automotive Technology》2011,12(1):39-44
Adequate visibility through the automobile windshield is of paramount practical significance, most often at very low temperatures
when ice tends to form on the windshield screen. But the numerical simulation of the defrost process is a challenging task
because phase change is involved. In this study numerical solution was computed by a finite volume computational fluid dynamics
(CFD) program and experimental investigations were performed to validate the numerical results. It was found that the airflow
produced by the defrost nozzle is highly nonuniform in nature and does not cover the whole windshield area. The nonuniformity
also severely affected the heating temperature pattern on the windshield. The windshield temperature reached a maximum in
the vicinity of the defroster nozzle in the lower part of the windshield and ranged from 9∼31°C over a period of 30 min, which
caused the frost to melt on the windshield. The melting time was under 10 minutes, which satisfied the NHTSA standard. The
numerical predictions were in close agreement with the experimental results. Thus, CFD can be a very useful design tool for
an automobile HVAC system. 相似文献
865.
C. -H. Lee J. -M. Lee M. -S. Choi C. -K. Kim E. -B. Koh 《International Journal of Automotive Technology》2011,12(2):193-198
Since the invention of automobiles, the need to know the braking performance of vehicles has been acknowledged. However, because
there are numerous design variables as well as nonlinearities in the braking system, it is difficult to predict the performance
accurately. In this paper, a computational program is developed to estimate the braking performance numerically. This synthetic
braking performance program accounts for pedal force, pedal travel and deceleration of braking parts, such as master cylinder,
booster, valve, brake pad, rotor, and hoses. To improve the accuracy of program, a semi-empirical model of a braking system
is introduced by using the empirical test data of pad compression, hose expansion and the friction coefficient between the
pad and rotor. The accuracy of the estimation is evaluated by comparing it to the actual vehicle test results. The developed
program is easy for the brake system engineers to manipulate and it can be used in the development of new vehicles by incorporating
the graphical presentations. 相似文献
866.
Head injuries are a major cause of fatalities in pedestrian-car accidents. The HIC (Head Injury Criterion) value, a measure of the fatality risk of a head injury, is calculated from the acceleration of the head’s center of gravity
(henceforth, head center) resulting from a head impact. The pedestrian’s head does not impact the hood at a direction normal
to the hood’s surface. The direction of motion of the head center may change extremely rapidly upon impact, and normal acceleration
may also significantly contribute to the resultant acceleration of the head center. Therefore, pedestrian head protection
studies should consider how normal acceleration contributes to the resultant acceleration of the head center. It is necessary
to control the resultant acceleration of the head center to produce an optimal characteristic pulse. This study analyzes the
composition and variations of the head’s acceleration in head-to-hood impacts, focusing on exactly how the normal and tangential
components of the acceleration contribute to the resultant acceleration of the head center. This study also considers how
structural design parameters affect each component of the resultant acceleration. Methods to control the resultant acceleration
of the head center to produce an optimal characteristic pulse can be proposed based on the results of this study. The analytical
models and the results of this study contribute to efforts to design vehicle hoods and pave the way for developing pedestrian
protection technologies. 相似文献
867.
This paper presents a methodology to optimize the sizing of the energy and power components in a fuel cell electric vehicle from the driving mission (which includes driving cycles, a specified acceleration and autonomy requirements). The fuel cell and the Energy Storage System associated (battery or/and ultra capacitor) design parameters are the numbers of series and parallel branches respectively Nsi and Npi. They are set so as to minimize the objective function that includes mass, cost, fulfilling the performance requirements and respect the technological constraints of each power component through a penalty function. The methodology is based on a judicious combination of Matlab-Simulink® for the global simulation and a dedicated software tool Pro@Design®. Both are well suited to treat inverse problems for the optimization. An application for a fuel cell/battery powertrain illustrates the feasibility of the proposed methodology. 相似文献
868.
W. M. Choi J. S. Kim H. S. Jung T. S. Kwon 《International Journal of Automotive Technology》2011,12(3):383-389
As a crash energy absorber, a tube-type crash element (expansion tube) dissipates kinetic energy through the internal deformation
energy of the tube and through frictional energy. In this paper, the effects of the variation of punch angles on the energy-absorbing
characteristics of expansion tubes were studied by quasi-static tests using three punch angles (15°, 30°, and 45°). A finite
element analysis of the tube expanding process (m = τ
max
/K) was performed using a shear friction model to confirm the variation of the shear friction factor with respect to punch angles
using the inverse method. Additional analyses were performed using angles of 20°, 25°, 35°, and 40° to study the effect of
the punch angles on the internal deformation energy, frictional energy, and expansion ratio of the tubes. The results of the
experiment and finite element analysis showed that the shear friction factor was inversely proportional to the punch angles,
and a specific punch angle existed at which the absorbed energy and expansion ratio remained constant. 相似文献
869.
The accurate estimation of sideslip angle is necessary for many vehicle control systems. The detection of sliding and skidding
is especially critical in emergency situations. In this paper, a sideslip angle estimation method is proposed that considers
severe longitudinal velocity variation over the short period of time during which a vehicle may lose stability due to sliding
or spinning. An extended Kalman filter (EKF) based on a kinematic model of a vehicle is used without initialization of the
inertial measurement unit to estimate vehicle longitudinal velocity. A dynamic compensation method that compensates for the
difference in the locations of the vehicle velocity sensor and the IMU in on-road vehicle tests is proposed. Evaluations with
a CarSim™ 27-degree-of-freedom (DOF) model for various vehicle test scenarios and with on-road tests using a real vehicle
show that the proposed sideslip angle estimation method can accurately predict sideslip angle, even when vehicle longitudinal
velocity changes significantly. 相似文献
870.
Proportional derivative (PD) steering assistance can greatly improve the control stability of a vehicle. However, for all
PD steering methods, the discomfort associated with the need to continuously turn the steering wheel during cornering is significant.
Because the steering return phenomenon of the steering wheel stop like this is not preferable, PD steering assistance should
be extremely weak (almost 0) during normal cornering. Alternatively, during drift cornering, during which the grip area of
the tires is exceeded, PD steering assistance is helpful because the driver has good control over counter-steering. Moreover,
the use of PD steering assistance is preferable during lane changes because the response and settling of a vehicle is greatly
improved when PD steering assistance is used. Based on these considerations, a previous report examined steering method controls
in which the PD steering assistance constant was incorporated along with the drivers’ perception changes in certain driving
situations. This study aimed to determine a suitable PD steering assistance constant in relation to the driving situation.
A proper PD steering assistance constant was found to exist for specific driving situations. Based on the results of gaze
detection using an eye mark recorder, the study was able to reduce the right and left difference of the gaze at the driver
by controlling PD steering assistance using a proper PD steering assistance constant for various driving situations. 相似文献