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Technical Paper

An Elementary Simulation of Vibration Isolation Characteristics of Hydraulically Damped Rubber Mount of Car Engine

2001-04-30
2001-01-1453
Hydraulically damped rubber engine mounts (HDM) are an effective means of providing sufficient isolation from engine vibration while also providing significant damping to control the rigid body motions of the engine during normal driving conditions. This results in a system which exhibits a high degree of non-linearity in terms of both frequency and amplitude. The numerical simulation of vibration isolation characteristics of HDM is difficult due to the fluid-structure interaction between the main supporting rubber and fluid in chambers, the nonlinear material properties, the large deformation of rubber parts, structure contact problems among the inner parts, and the turbulent flow in the inertia track. In this paper an integrated numerical simulation analysis based on structural FEM and a lumped-parameter model of HDM is carried out.
Technical Paper

Simulations on Special Structure ISG Motor Used for Hybrid Electrical Vehicles Aimed at Active Damping

2017-03-28
2017-01-1123
Engine torque fluctuation is a great threat to vehicle comfort and durability. Former researches tried to solve this problem by introducing active damping system, which means the motor is controlled to produce torque ripple with just the opposite phase to that of the engine. By this means, the torque fluctuation produced by the motor and the engine can be reduced. In this paper, a new method is raised. An attempt is proposed by changing the traditional structure of the motor, making it produce ripple torque by itself instead of controlling the motor. In this way a special used ISG (Integrated Starter Generator) motor for HEV (Hybrid Electrical Vehicles) is made to achieve active damping. In order to study the possibility, a simulation, which focus on the motor instead of the whole system, is developed and series-parallel configuration is used in this simulation. As for the motor that used in this paper, four kinds of motors have been investigated and compared.
Technical Paper

Research on Vehicle Stability Control Strategy Based on Integrated-Electro-Hydraulic Brake System

2017-03-28
2017-01-1565
A vehicle dynamics stability control system based on integrated-electro-hydraulic brake (I-EHB) system with hierarchical control architecture and nonlinear control method is designed to improve the vehicle dynamics stability under extreme conditions in this paper. The I-EHB system is a novel brake-by-wire system, and is suitable to the development demands of intelligent vehicle technology and new energy vehicle technology. Four inlet valves and four outlet valves are added to the layout of a conventional four-channel hydraulic control unit. A permanent-magnet synchronous motor (PMSM) provides a stabilized high-pressure source in the master cylinder, and the four-channel hydraulic control unit ensures that the pressures in each wheel cylinder can be modulated separately at a high precision. Besides, the functions of Anti-lock Braking System, Traction Control System and Regenerative Braking System, Autonomous Emergency Braking can be integrated in this brake-by-wire system.
Technical Paper

Fuel Economy Analysis of Periodic Cruise Control Strategies for Power-Split HEVs at Medium and Low Speed

2018-04-03
2018-01-0871
Hybridization of vehicles is considered as the most promising technology for automakers and researchers, facing the challenge of optimizing both the fuel economy and emission of the road transport. Extensive studies have been performed on power-split hybrid electric vehicles (PS-HEVs). Despite of the fact that their excellent fuel economy performance in city driving conditions has been witnessed, a bottle neck for further improving the fuel economy of PS-HEVs has been encountered due to the inherent engine-generator-motor power circulation of the power-split system under medium-low speed cruising scenarios. Due to the special mechanical constraints of the power-split device (PSD), the conventional periodic cruising strategy like Pulse and Glide cannot be applied to PS-HEVs directly.
Technical Paper

Mission-based Design Space Exploration for Powertrain Electrification of Series Plugin Hybrid Electric Delivery Truck

2018-04-03
2018-01-1027
Hybrid electric vehicles (HEV) are essential for reducing fuel consumption and emissions. However, when analyzing different segments of the transportation industry, for example, public transportation or different sizes of delivery trucks and how the HEV are used, it is clear that one powertrain may not be optimal in all situations. Choosing a hybrid powertrain architecture and proper component sizes for different applications is an important task to find the optimal trade-off between fuel economy, drivability, and vehicle cost. However, exploring and evaluating all possible architectures and component sizes is a time-consuming task. A search algorithm, using Gaussian Processes, is proposed that simultaneously explores multiple architecture options, to identify the Pareto-optimal solutions.
Technical Paper

Emergency Steering Evasion Control by Combining the Yaw Moment with Steering Assistance

2018-04-03
2018-01-0818
The coordinated control of stability and steering systems in collision avoidance steering evasion has been widely studied in vehicle active safety area, but the studies are mainly aimed at autonomous vehicle without driver or conventional combustion engine vehicle. This paper focuses on the control of hybrid vehicle integrated with rear hub in emergency steering evasion situation, and considering the driver’s characteristics. First, the mathematics model of vehicle dynamics and driver has been given. Second, based on the planned steering evasion path, the model predictive control method is presented for achieving higher evasion path tracking accuracy under driver’s steering input. The prediction model includes an adaptive preview distance driver model and a vehicle dynamics model to predict the driver input and the vehicle trajectory.
Technical Paper

Design Optimization of the Transmission System for Electric Vehicles Considering the Dynamic Efficiency of the Regenerative Brake

2018-04-03
2018-01-0819
In this paper, gear ratios of a two-speed transmission system are optimized for an electric passenger car. Quasi static system models, including the vehicle model, the motor, the battery, the transmission system, and drive cycles are established in MATLAB/Simulink at first. Specifically, since the regenerative braking capability of the motor is affected by the SoC of battery and motors torque limitation in real time, the dynamical variation of the regenerative brake efficiency is considered in this study. To obtain the optimal gear ratios, iterations are carried out through Nelder-Mead algorithm under constraints in MATLAB/Simulink. During the optimization process, the motor efficiency is observed along with the drive cycle, and the gear shift strategy is determined based on the vehicle velocity and acceleration demand. Simulation results show that the electric motor works in a relative high efficiency range during the whole drive cycle.
Technical Paper

Recycling-Based Reduction of Energy Consumption and Carbon Emission of China’s Electric Vehicles: Overview and Policy Analysis

2018-04-03
2018-01-0659
Electric vehicles maintain the fastest development in China and undertake the responsibility of optimizing energy consumption and carbon emission in the transportation field. However, from the entire life cycle point of view, although electric vehicles have a certain degree of energy consumption and carbon emission reduction in the use phase, they cause extra energy consumption and carbon emission in the manufacturing phase, which weakens the due environmental benefits to some extent. The recycling of electric vehicles can effectively address the issue and indirectly reduce the energy consumption and carbon emission in the manufacturing phase. China is setting up the recycling system and strengthening regulation force to achieve proper energy consumption and carbon emission reduction benefits of electric vehicles. Under the current electric vehicle recycling technologies, China can reduce about 34% of carbon emission in electric vehicle manufacturing phase.
Technical Paper

Effect of Single and Double-Deck Pre-Chamber Designs to the Combustion Characteristics of Premixed CH4 /Air

2018-09-10
2018-01-1688
An experiment was carried out to investigate the effect of single and double-deck pre-chamber on the combustion characteristics of premixed CH4/air in a constant volume vessel using schlieren method. A special design was proposed for the visualization of the pre-chamber. Combustion with different initial temperatures (300 K, 400 K, 500 K) were observed at stoichiometric ratio to lean-burn limit. Although single-deck pre-chamber has advantages over double-deck pre-chamber in both initial flame development duration and main combustion duration, the latter could extend the lean-burn limit by up to 0.3 and promote the stability of ignition. It is also found that extensive distribution of active species in main chamber before ignition can accelerate speed of flame propagation enormously.
Technical Paper

The 3-Dimensional Modal Parameter Tire Model and Simulation of Tire Rolling Over Oblique Cleats

2008-04-14
2008-01-1408
Based on the simulation results of tire rolling over perpendicular cleats by MPTM model, in present paper, a series of simulation results of tire rolling over oblique cleats with different angles are given. For that, the Modal Parameter Tire Camber property Model is established. For the appraisement of comparison between simulation and experimental results a problem concern the validation test is pointed out. In the end, simulation results of tire rolling over a series of continuous cleats are given.
Technical Paper

Research of the Primary Breakup of a Planar Liquid Sheet Produced by an Air-Blast Atomizer

2014-04-01
2014-01-1430
The primary breakup of a planar liquid sheet produced by an air-blast atomizer was studied through numerical simulations, in order to reveal physical mechanisms involved during this process. The reliability of simulations was verified by comparing the macroscopic parameters, e.g. breakup time and spatial growth rate, with experimental data. Shear instability and RT (Rayleigh-Taylor) instability were found to play important roles during the primary breakup. By analyzing the acceleration of a fluid parcel within liquid sheet using Discrete Particle Method, and measuring the wave length of transverse unstable wave, RT instability was found to be partially responsible for transverse instability. The predictions of LISA (Linearized Instability Sheet Atomization) model on breakup time were compared to experiments, and obvious differences were found to exist.
Technical Paper

Research on Driving Range Estimation for Electric Vehicles Based on Corrected Battery Model

2015-04-14
2015-01-0250
In order to reduce driver's anxiety about range and energy, a direct and effective approach is to offer the remaining driving range based on the vehicle's states. Consequently, the estimation accuracy of the battery's remaining energy is very important. This paper introduces a experiment-based model for predicting the remaining energy, which considers many factors, such as current, temperature, difference between battery cells, and so on. This approach ensures the accuracy of the remaining driving range. Finally the method is validated through the environment space test. Validation results show that this method can offer exact remaining energy, which reduces the estimation error of the remaining range greatly.
Technical Paper

Influence of Mass Distribution of Battery and Occupant on Crash Response of Small Lightweight Electric Vehicle

2015-04-14
2015-01-0575
Small lightweight electric vehicle (SLEV) is an approach for compensating low energy density of the current battery. However, small lightweight vehicle presents technical challenges to crash safety design. One issue is that mass of battery pack and occupants is a significant portion of vehicle's total weight, and therefore, the mass distribution has great influence on crash response. This paper presents a parametric analysis using finite element modeling. We first build LS-DYNA model of a two-seater SLEV with curb weight of 600 kg. The model has no complex components and can provide reasonable crash pulses under full frontal rigid barrier crash loading and offset deformable barrier (ODB) crash loading. For given mass of battery pack and one occupant (the driver), different battery layouts, representing different combinations of center of gravity and moment of inertia of the whole vehicle, are analyzed for their influences on the crash responses under the two frontal crash loadings.
Technical Paper

Estimation of Road-Tire Friction with Unscented Kalman Filter and MSE-Weighted Fusion based on a Modified Dugoff Tire Model

2015-04-14
2015-01-1601
This paper proposes an estimation method of road-tire friction coefficient for the 4WID EV(4-wheel-independent-drive electric vehicle) in the pure longitudinal wheel slip, lateral sideslip and combined slip situations, which fuses both estimated longitudinal and lateral friction coefficients together, compared with existing methods based on a tire model in one single direction. Unscented Kalman filter (UKF) is introduced to estimate one-directional friction coefficient based on a modified Dugoff tire model. Considering the output results for each direction as a signal for the same target with different noise, MSE-weighted fusion method is proposed to fuse these two results together in order to reach a higher accuracy. The tire forces are estimated with the benefits of the 4WID EV that the driving torque and rolling speed of each wheel can be accurately known. The sideslip angles and slip ratios of each tire are calculated with a vehicle kinematic model.
Technical Paper

Effects of Sinusoidal Whole Body Vibration Frequency on Drivers' Muscle Responses

2015-04-14
2015-01-1396
Low back pain has a higher prevalence among drivers who have long term history of vehicle operations. Vehicle vibration has been considered to contribute to the onset of low back pain. However, the fundamental mechanism that relates vibration to low back pain is still not clear. Little is known about the relationship between vibration exposure, the biomechanical response, and the physiological responses of the seated human. The aim of this study was to determine the vibration frequency that causes the increase of muscle activity that can lead to muscle fatigue and low back pain. This study investigated the effects of various vibration frequencies on the lumbar and thoracic paraspinal muscle responses among 11 seated volunteers exposed to sinusoidal whole body vibration varying from 4Hz to 30Hz at 0.4 g of acceleration. The accelerations of the seat and the pelvis were recorded during various frequency of vibrations. Muscle activity was measured using electromyography (EMG).
Technical Paper

Numerical Study of Pressure Swirl Spray Using an Improved KIVALES with Dense Grid for GDI Engine

2013-10-14
2013-01-2558
Gasoline direct injection engines can greatly improve the fuel economy, but the idea mixture distribution cannot be easily controlled. In this paper, the linearized instability sheet atomization (LISA) and large eddy simulation (LES) implemented into KIVA-3V code were used to study the gasoline hollow cone spray process for gasoline direct injection (GDI) in a constant volume vessel. The three-dimensional results show that the LISA model can effectively simulate the gasoline hollow cone spray and obtain the string structure compared to the experiment data. And the velocity interpolation method can reduce the grid dependency of spray simulation. Using dense grid (about 8 million cells) in LES and RANS all can obtain the good spray tip penetration and width. Unlike diesel spray, for gasoline spray there are not big difference between the results using LES and RANS. In additional the ambient pressure significantly influence the gasoline spray shape.
Technical Paper

A Dynamic Model for Tire/Road Friction Estimation under Combined Longitudinal/Lateral Slip Situation

2014-04-01
2014-01-0123
A new dynamic tire model for estimating the longitudinal/lateral road-tire friction force was derived in this paper. The model was based on the previous Dugoff tire model, in consideration of its drawback that it does not reflect the actual change trend that the tire friction force decreases with the increment of wheel slip ratio when it enters into the nonlinear region. The Dugoff model was modified by fitting a series of tire force data and compared with the commonly used Magic Formula model. This new dynamic friction model is able to capture accurately the transient behavior of the friction force observed during pure longitudinal wheel slip, lateral sideslip and combined slip situation. Simulation has been done under different situations, while the results validate the accuracy of the new tire friction model in predicting tire/road friction force during transient vehicle motion.
Technical Paper

Large Eddy Simulation of Liquid Fuel Spray and Combustion with Gradually Varying Grid

2013-10-14
2013-01-2634
In this work, large eddy simulation (LES) with a K-equation subgrid turbulent kinetic energy model is implemented into the CFD code KIVA3V to study the features of liquid fuel spray and combustion using gradually varying grid in a constant volume chamber. The characteristic time-scale combustion model (CTC) incorporating a turbulent timescale is adopted to predict the combustion process and the SHELL auto-ignition model is used to predict auto-ignition. Combustion is also simulated using Parallel Detailed Chemistry with Lu's n-heptane reduced mechanism (58 species), which has been added into the KIVA3V-LES code. The computational results are compared with Sandia experimental data for non-reacting and reacting cases. As a result, LES can capture the complex structure of the spray and temperature distribution as well as the trend of ignition delay and flame lift-off length variations. Better results are obtained using the Parallel Detailed Chemistry than the CTC model.
Technical Paper

Predicting the Battery Residual Usable Energy under Dynamic Conditions: a Novel Adaptive Method with Enhanced Performance

2015-03-10
2015-01-0054
Electric vehicle (EV) is a worldwide researching focus due to its environmental friendliness, but the inaccurate Remaining Driving Range (RDR) estimation hinders the EVs' popularity, and an accurate determination of the battery Residual Usable Energy (RUE) is the key factor to obtain a precise RDR value. A common RUE estimation method is based on State-of-Charge (SOC) estimation, in which the RUE is proportionally related to the current SOC. However, the battery voltage varies significantly under real-world conditions, and the traditional method results in certain estimation errors. An adaptive RUE prediction method (AEP) is introduced in this paper, in which the dynamic voltage is predicted based on the future discharge profile and a battery model, while the RUE is then calculated by the predicted voltage and current sequences.
Technical Paper

Analysis of Energy Consumption on Typical Main Cylinder Booster Based Brake-by-Wire System

2016-09-18
2016-01-1955
The traditional vacuum booster is gradually replaced by Brake-by-Wire system (BBW) in modern passenger car, especially Electric Vehicle (EV). Some mechanical and hydraulic components are replaced by electronic components in Brake-by-Wire system. Using BBW system in modern passenger vehicles can not only improve the automotive safety performance, reliability and stability, but also promote vehicle maneuverability, comfort, fuel economy and environmental protection. Although vehicle's braking performance is greatly improved by using BBW, the system will inevitably consume some energy of the vehicle power supply, thus introducing unexpected drawback in comparison with the traditional vacuum assist braking system, since it doesn't need any electric power. Therefore, the analysis of energy consumption on typical main cylinder booster based BBW system under typical driving cycles will contribute to advanced design of current advanced braking system.
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