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741.
742.
743.
在过去几年里,中国试图将新能源汽车开发领先于世界。但高成本、技术落后和低动力继续阻止了新能源汽车的量产。两年前,《纽约时报》曾刊登了一篇题为“中国力争成为世界电动汽车的领头羊”的文章,报道了中国汽车产业政策制订者将中国定位于“在未来三年内”成为全球领先的绿色能源汽车生产国之一。 相似文献
744.
Wet multi-plate friction clutches are used in automotive drivelines to transfer torque, change gears, and prevent motion by
locking-up components in the transmission. The control strategy of starting is a crucial technology for the application of
a wet multi-plate friction clutch in the automotive industry. In this paper, a multi-state fuzzy control strategy for starting
is presented and applied to a continuously variably transmission (CVT) powertrain for the validation of this strategy. The
operation of the clutch was divided into four states: parking, starting, riding and emergency. The starting state was investigated
in detail. A fuzzy algorithm was employed to control the pressure of the hydraulic cylinder acting on the clutch. A distinguishing
feature is that the pressure does not increase but decreases to implement smooth starting during the initial period of starting.
The rapid-control prototype (RCP) of the wet friction clutch was developed to validate the new control strategy onboard a
test vehicle. Based on the experimental results, the multi-state control strategy for a wet friction clutch is a viable candidate
for engineering applications. 相似文献
745.
J.-H. Kim J.-M. Seo J. H. Jung N.-K. Hur 《International Journal of Automotive Technology》2011,12(3):417-423
Manufacturers of commercial vehicles are facing a substantial increase of heat release into their cooling systems. The main
sources for this increase are more stringent emissions leading to new combustion technologies and the increased power of these
engines. The total increase in the cooling requirement may be up to 20% over the current level. At the same time, the noise
levels must be decreased, and fuel economy has to improve. This forces manufacturers to consider new concepts and optimize
the efficiency of the cooling system. A bus engine cooling fan system is one of the main means of vehicular fuel efficiency
reduction. This is becoming a major factor in city noise, and the necessity of electromagnetic technical development is very
great. This study features a highly effective BLDC motor for engine cooling fans with high effectiveness and low noise, which
is most suitable for fan blade technical development and cooling fan performance evaluation technical development. 相似文献
746.
In this research, the concept of the kinematic roll center is reviewed from the viewpoint of three-dimensional spatial kinematics.
The theory of screws, which is widely used in spatial kinematics and robotics, is used to prove the validity of the conventional
planar methods for finding the roll center in an initial symmetric vehicle position. The kinematic roll axis, which is referred
to as the roll twist axis in this paper, is defined as the instantaneous screw axis of the vehicle body in roll motion with
respect to the ground, and a three-dimensional method to determine the roll twist axis of a full-vehicle model in an initial
symmetric position is introduced. The proposed method is based on screw theory, which relates the kinematics of a full-vehicle
model to the statics of the full-vehicle model using the concepts of screws, twists, wrenches, the rate of working, and the
reciprocity of screws. The results of the proposed three-dimensional method are compared with those of the conventional planar
methods, and it is found that the conventional methods are valid under the assumption that the vehicle is in a symmetric situation. 相似文献
747.
D. W. Pi N. Chen J. X. Wang B. J. Zhang 《International Journal of Automotive Technology》2011,12(3):391-399
This paper presents a method for estimating the vehicle side slip angle, which is considered as a significant signal in determining
the vehicle stability region in vehicle stability control systems. The proposed method combines the model-based method and
kinematics-based method. Side forces of the front and rear axles are provided as a weighted sum of directly calculated values
from a lateral acceleration sensor and a yaw rate sensor and from a tire model according to the nonlinear factor, which is
defined to identify the degree of nonlinearity of the vehicle state. Then, the side forces are fed to the extended Kalman
filter, which is designed based on the single-track vehicle model associated with a tire model. The cornering stiffness identifier
is introduced to compensate for tire force nonlinearities. A fuzzy-logic procedure is implemented to determine the nonlinear
factor from the input variables: yaw rate deviation from the reference value and lateral acceleration. The proposed observer
is compared with a model-based method and kinematics-based method. An 8 DOF vehicle model and Dugoff tire model are employed
to simulate the vehicle state in MATLAB/SIMULINK. The simulation results shows that the proposed method is more accurate than
the model-based method and kinematics-based method when the vehicle is subjected to severe maneuvers under different road
conditions. 相似文献
748.
This paper describes a drive controller designed to improve the lateral vehicle stability and maneuverability of a 6-wheel
drive / 6-wheel steering (6WD/6WS) vehicle. The drive controller consists of upper and lower level controllers. The upper
level controller is based on sliding control theory and determines both front and middle steering angle, additional net yaw
moment, and longitudinal net force according to the reference velocity and steering angle of a manual drive, remotely controlled,
autonomous controller. The lower level controller takes the desired longitudinal net force, yaw moment, and tire force information
as inputs and determines the additional front steering angle and distributed longitudinal tire force on each wheel. This controller
is based on optimal distribution control and takes into consideration the friction circle related to the vertical tire force
and friction coefficient acting on the road and tire. Distributed longitudinal/lateral tire forces are determined as proportion
to the size of the friction circle according to changes in driving conditions. The response of the 6WD/6WS vehicle implemented
with this drive controller has been evaluated via computer simulations conducted using the Matlab/Simulink dynamic model.
Computer simulations of an open loop under turning conditions and a closed-loop driver model subjected to double lane change
have been conducted to demonstrate the improved performance of the proposed drive controller over that of a conventional DYC. 相似文献
749.
Model development and experimental research on an air spring with auxiliary reservoir 总被引:1,自引:0,他引:1
This paper focuses on the dynamic stiffness and overall equivalent damping of an air spring connected to an orifice and an
auxiliary reservoir, with respect to the displacement excitation frequency, orifice area, and auxiliary reservoir volume.
A theoretical model of this air spring with its auxiliary reservoir is derived by utilizing the energy conservation equation,
gas state equation, and orifice flow rate equation. Simulation results from the presented model reveal that, when the air
spring is subject to harmonic displacement excitation, its dynamic stiffness increases with an increase in excitation frequency
and decrease in orifice area. Smaller orifice areas and lower excitation frequencies result in higher overall equivalent damping.
A validation experiment is also implemented. When compared with experimental results, simulations show consistent varying
trends of the dynamic stiffness and overall equivalent damping. The model developed here can correctly describe the behavior
of the air spring with auxiliary reservoir, indicating that it is reasonable and feasible. 相似文献
750.
J. Abraham 《International Journal of Automotive Technology》2011,12(5):721-732
Under light-load conditions in early-injection stratified-charge compression-ignition (SCCI) engines, excessive premixing
can lead to undesirable levels of unburned hydrocarbons (UHC) and carbon monoxide (CO) emissions. Optimal stratification can
reduce these emissions. In this work, the effects of changes in swirl, injection pressure, injector hole-size and number of
holes, injection timing, and piston geometry on stratification are computationally investigated. It is shown that these parameters
affect the stratification through their influence on the rate of spray penetration, drop vaporization, and fuel/air mixing.
The outcome is characterized by examining the evolution of the spatial distribution of the fuel vapor in the chamber and its
mass-based distribution function. All other parameters remaining the same, decreasing drop size leads to faster vaporization
and richer mixtures. Increasing penetration leads to greater spreading and leaner mixtures. Increasing spray included-angle
leads to greater spreading and leaner mixtures. Increasing injection pressure leads to increased mixing and leaner mixtures.
Increasing injector hole-size leads to richer mixtures at lighter loads because the duration of injection is reduced and the
fuel is confined closer to the axis. Increasing swirl leads to faster breakup of the head-vortex and confinement of the fuel
closer to the axis, and hence richer mixture. 相似文献