汽车空气弹簧的应用现状及发展趋势

文章介绍了空气弹簧在我国的应用与发展现状，重点叙述了空气弹簧的结构原理和特点，须解决的关键技术及未来发展趋势。     

Performance evaluation and parameter sensitivity of energy-harvesting shock absorbers on different vehicles

Traditional shock absorbers provide favourable ride comfort and road handling by dissipating the suspension vibration energy into heat waste. In order to harvest this dissipated energy and improve the vehicle fuel efficiency, many energy-harvesting shock absorbers (EHSAs) have been proposed in recent years. Among them, two types of EHSAs have attracted much attention. One is a traditional EHSA which converts the oscillatory vibration into bidirectional rotation using rack-pinion, ball-screw or other mechanisms. The other EHSA is equipped with a mechanical motion rectifier (MMR) that transforms the bidirectional vibration into unidirectional rotation. Hereinafter, they are referred to as NonMMR-EHSA and MMR-EHSA, respectively. This paper compares their performances with the corresponding traditional shock absorber by using closed-form analysis and numerical simulations on various types of vehicles, including passenger cars, buses and trucks. Results suggest that MMR-EHSA provides better ride performances than NonMMR-EHSA, and that MMR-EHSA is able to improve both the ride comfort and road handling simultaneously over the traditional shock absorber when installed on light-damped, heavy-duty vehicles. Additionally, the optimal parameters of MMR-EHSA are obtained for ride comfort. The optimal solutions (‘Pareto-optimal solutions’) are also obtained by considering the trade-off between ride comfort and road handling.     

Efficient empirical modelling of a high-performance shock absorber for vehicle dynamics studies

This paper develops an intuitive empirical nonlinear dynamic shock absorber model for simulation studies. Unlike other existing dynamic shock absorber models, it does not suffer from the complexity of modelling complex physical behaviour, or the inefficiencies of unstructured black-box modelling. The model consists of an algebraic backbone, which is a function of velocity alone, and a nonlinear low-pass filter, which has been designed based on the observation that the damper can respond more quickly at higher velocities. Due to the simplicity of the model, it can be fitted with data and evaluated quickly. The model was fitted using shock dynamometer test data using a random shock position command. The completed model is then validated using random, sine wave, and bump test data. This analysis shows the strengths and weaknesses of the model and suggests areas for future development.     

浅谈车载终端的技术发展方向

随着电子商务的兴起和智能设备技术的发展,对物流和运输行业的需求日益增加,滚滚的车轮给人类日常生活和社会发展带来了便捷、进步的同时,诸如交通堵塞、交通事故频发、环境污染和能源消耗等问题日益凸显,直接经济损失巨大。车联网技术实现智能交通,必定是以后发展的趋势。而车载智能终端作为车联网技术的基础,更是未来的研究方向。本文正是在此背景下,阐述了车载终端的发展现状和存在问题,探索未来的技术发展方向。     

Velocity and normal tyre force estimation for heavy trucks based on vehicle dynamic simulation considering the road slope angle

A precise estimation of vehicle velocities can be valuable for improving the performance of the vehicle dynamics control (VDC) system and this estimation relies heavily upon the accuracy of longitudinal and lateral tyre force calculation governed by the prediction of normal tyre forces. This paper presents a computational method based on the unscented Kalman filter (UKF) method to estimate both longitudinal and lateral velocities and develops a novel quasi-stationary method to predict normal tyre forces of heavy trucks on a sloping road. The vehicle dynamic model is constructed with a planar dynamic model combined with the Pacejka tyre model. The novel quasi-stationary method for predicting normal tyre forces is able to characterise the typical chassis configuration of the heavy trucks. The validation is conducted through comparing the predicted results with those simulated by the TruckSim and it has a good agreement between these results without compromising the convergence speed and stability.     

军用车载计算机环境及可靠性试验方法浅析

简要介绍了我军新型车载计算机的考核试验方法,阐述了军用车载计算机环境试验、可靠性试验的试验条件、试验方法及判定标准,为我军新研车载电子设备的考核试验提供参考。     

Material characteristics of a vehicle door seal and its effect on vehicle vibrations

The vibration characteristics of the door panels are affected by the weatherstrip seals used in between the doors and vehicle body along the perimeter of the doors. The weatherstrip seals exhibit nonlinear and viscoelastic material properties that vary with frequency, temperature, strain rate and amplitude, and previous load history. The material properties of the seal must be investigated carefully in order to predict the vibration characteristics of the automobiles under different loading conditions.

In this study, we developed hyperelastic and viscoelastic models of the weatherstrip seal to predict dynamic performance of a vehicle door and its effect on the overall vehicle dynamics. For this purpose, first, static compression and stress relaxation experiments were performed on the seal using a robotic indenter equipped with force and displacement sensors and then a finite element model utilising the results of these experiments was developed in ANSYS. Finally, a representative model of the seal was integrated into the finite element model of the vehicle door to investigate its effect on the vehicle vibrations. The model predictions were validated using experimental modal analysis performed on the vehicle door with and without the seal. It was observed that the seal has a significant effect on the vehicle dynamics.     

Experimental investigations on the damping effect due to passengers on flexural vibrations of railway vehicle carbody and basic studies on the mimicry of the effect with simple substitutions

The effect of passengers on a railway vehicle is usually considered as additional mass in designing a carbody. However, previous studies by means of stationary excitation tests or running tests using actual vehicles indicate that passengers behave not as mass but as damping. In this paper, the authors examined the passengers' damping effect under controlled excitation conditions on a roller rig through a series of excitation tests using a commuter-type vehicle. Large and multi-modal reductions of flexural vibrations of the carbody were observed when passengers existed. Influences of the number of passengers, distributions and postures of passengers were investigated. The authors also tried to mimic the damping effect by passengers using flexible tanks filled with fluids. Three kinds of fluids which have different viscosities have been tested. As a result of the excitation tests, good vibration reduction effects were observed by applying those tanks, and it has been found that the flexible tanks filled with fluids bring about vibration reduction effect (including multi-modal reduction) which is equal to or rather better than the case of similar mass of passengers in the carbody; the difference of viscosity gave little affect on the damping abilities. From these measurement results, a possibility of realising effective damping devices against flexural vibrations of railway vehicle carbodies representing passengers damping effect, in a simple, economical and environmental friendly way, has been demonstrated.     

Validation of the 6-dof vehicle dynamics model and its related VBA program under the constant radius turn manoeuvre

For a 6-dof (degrees of freedom) nonlinear vehicle dynamics model and its related VBA (Visual Basic for Applications) program, which were recently derived and coded by the authors, validations are carried out under the constant radius turn manoeuvre. This model has the uniqueness that the longitudinal translation, lateral translation and yaw rotation of a platform are described by an inertial ground coordinate system and the body-roll, body-pitch, and body-yaw rotations by a platform-fixed coordinate system. The simplified STI tire model is applied for the calculation of combined longitudinal and lateral tire forces. Vehicles used in the calculation are a NISSAN DATSUN 210 (manufactured in 1980) and a HONDA ACCORD (1984). The calculation results of the present 6-dof model are compared with the published test data and those of a simpler 3-dof lateral dynamic equation based on another coordinate system. As a result of the comparison, the present 6-dof results agree very well with those of the 3-dof model and give a partial consistency with the test data.     

Extended-Kalman-filter-based regenerative and friction blended braking control for electric vehicle equipped with axle motor considering damping and elastic properties of electric powertrain

Because of the damping and elastic properties of an electrified powertrain, the regenerative brake of an electric vehicle (EV) is very different from a conventional friction brake with respect to the system dynamics. The flexibility of an electric drivetrain would have a negative effect on the blended brake control performance. In this study, models of the powertrain system of an electric car equipped with an axle motor are developed. Based on these models, the transfer characteristics of the motor torque in the driveline and its effect on blended braking control performance are analysed. To further enhance a vehicle's brake performance and energy efficiency, blended braking control algorithms with compensation for the powertrain flexibility are proposed using an extended Kalman filter. These algorithms are simulated under normal deceleration braking. The results show that the brake performance and blended braking control accuracy of the vehicle are significantly enhanced by the newly proposed algorithms.     

Study on construction of a rider robot for two-wheeled vehicle

In this study, we constructed a fully autonomous two-wheeled vehicle (the Rider Robot) which was used for evaluation of dynamics. As the first step of the study, we constructed the control algorithms and the control system.The control algorithms consist of the standing stability control which keeps the perpendicular motion, and the directional control which follows the target course. These algorithms were determined based on human rider's behavior. The system was constructed using some actuators and sensors.The results show that Rider Robot could follow the target course while keeping the standing stability. Consequently, there is considerable validly in these constructed algorithms and the system.     

Effects of model response on model following type of combined lateral force and yaw moment control performance for active vehicle handling safety

This paper presents a comparison study of the effect of model response on the performance of the model following type combined lateral force and yaw moment control. The combined controls aim to maximize stability limit as well as vehicle responsiveness. In order to realize this aim, two types of model responses are proposed to introduce the required lateral force and yaw moment control. The model responses (a) is the side-slip angle and yaw rate vehicle response of the two degree of freedom vehicle motion (bicycle model). The model responses (b) is an intentional modification from the model responses (a) to the side slip angle converging to zero and first order yaw rate. Three different cases of combining lateral force and yaw moment control have been investigated using the two types of model responses. The effect of model responses is proved by computer simulations of the vehicle response to a single sine wave steering input with braking for the combined control methods proposed. It is found that the influence of the model response has a significant effect on the combined control performance.     

基于ADAMS的某车型转向特性分析

用ADAMS软件建立了某车型转向传动机构的虚拟样机模型,分析了转向机构中的关键点改变对阿克曼转向特性的影响,为新车型开发过程中转向梯形的选择提供了最佳方向。     

Development of the brake system design program for a vehicle

It is quite challenging to estimate the braking performance of a vehicle because the brake system is comprised of many parts, including a booster, master cylinder, and caliper. Calculation of characteristics such as braking force through vehicle tests requires much time and money. Therefore, the development of a method to estimate the braking performance of a vehicle using qualitative methods is beneficial. In this study, a program that can analyze the braking capabilities of a vehicle such as pressure, efficiency, and pedal travel is presented. The increase in disc temperature during braking as well as the properties of various boosters can be calculated using the proposed program. Dynamic characteristics of a vehicle equipped with a Load Sensing Proportional Valve (LSPV) were computed more precisely by obtaining the change in valve pressure according to the displacement of a suspension system. Since all input and output files are composed in the Microsoft Excel format, both design data management and database construction can easily completed.     

浅析插电式混合动力功能样车试制方法

针对某款插电式混合动力汽车(PHEV)特点,依据功能样车验证需求逆向解析样车试制要求,并以此开展试制验证工作,满足不断提升的产品研发质量需求,达成项目QCD最优。本文从解析样车要求、试制方案设计、样车评价三方面介绍功能样车试制验证方法。     

On vehicle/track impact at connection between a floating slab and ballasted track and floating slab track's effectiveness of force isolation

When a vehicle runs over the connection between a floating slab track (FST) and ballasted track, wheel/rail impact may occur because of the stiffness difference in the two kinds of track, and thus a transition sector is usually included at the connection to smoothen the stiffness change. This phenomenon is studied by numerical simulation using a time-domain model for an idealised case without such a transition to determine whether it is actually necessary. Calculation results show that the wheel/rail impact load is moderate for a light FST and increases with the vehicle speed or decreasing the natural frequency of the FST. From simulation the wheel/rail parametric excitation is observed, as a result of variation in the stiffness of the FST with the period of the single slab length. The wheel/rail load due to the parametric excitation also increases with the vehicle speed. In addition, good performance of vibration isolation can be seen for the FST in terms of the force transmitted to the infrastructure.     

Development of a semi-empirical program for predicting the braking performance of a passenger vehicle

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.     

A study on a dynamic model of a vehicle simulator with 6 DOF for the Korean tilting train

This article presents a dynamic model of a railway vehicle for the development of a 6-DOF (degrees of freedom) tilting-train simulator. It will be used to verify the tilting-electronics and tilting-control algorithm that are to be applied to the Korean tilting train. It is composed of 6 electrically driven actuators, a track generation system, a graphic user interface, and a visualization system with a 1600-mm-diameter dome screen. Each system shares the data by means of Ethernet network in real time. In this study, a train model of 9-DOF with a force generation system to tilt the train body has been used. Dynamic analysis for the straight track running and curve negotiation of a railway vehicle can be performed in the model. A verification study for the application of the model to the simulator has been conducted on curving tracks with different radii.