汽车ABS和转向特性

汽车制动防车轮抱死机构（ABS）的作用汽车地面制动力学表明，汽车制动时随车轮抱死程度（车轮与地面的滑移率）的提高，在制动过程中，轮胎与地面的摩擦系数会同步下降，当轮胎抱死时，将失去抗侧力，只要有一点侧向力汽车就甩尾。为克服汽车制动时造成地面附着率的下降，汽车工程师发明了车轮制动时防抱死机构即PABS系统。有人会问，汽车刹车连轮胎都不会抱死，不是会延长刹车距离吗？其实不然，     

汽车ABS和转向特性

汽车制动防车轮抱死机构（ABS）的作用汽车地面制动力学表明，汽车制动时随车轮抱死程度（车轮与地面的滑移率）的提高，在制动过程中，轮胎与地面的摩擦系数会同步下降，当轮胎抱死时，将失去抗侧力，只要有一点侧向力汽车就甩尾。为克服汽车制动时造成地面附着率的下降，汽车工程师发明了车轮制动时防抱死机构即PABS系统。有人会问，汽车刹车连轮胎都不会抱死，不是会延长刹车距离吗？其实不然，     

冰雪路面如何安全驾驶

深冬时节,冰雪路面附着系数小,路面滑,给汽车行驶造成困难,处理不好便会发生轮胎打滑、侧滑、制动后停不住车等危险。那么,冰雪路面应该如何驾驶车辆呢?首先,由于制动距离会随着车速的提高而加大,所以控制车速和加大前后车距是冰雪路面行驶的关键。其次,要注意以下要诀:     

汽车气制动ABS调节阀测试系统气动测试回路设计研究

针对气制动防抱死制动系统(ABS)调节阀测试系统气动回路设计进行研究;根据我国的汽车生产和检测现状,在确定气动测试回路总体方案的基础上,进行主控部分、负载回路、控制回路的设计和计算,所设计的气路检测系统可用于测试8种典型的气制动元件的密封性及动静态特性,通过不同的组合能够满足每一种阀的测试需求。该气动测试回路有效解决了简单阀类测量方法的不足,满足不了生产率及测量精度要求的问题。     

汽车的操纵性与稳定性

汽车的操纵性是指汽车能准确地，按照驾驶员的操作指令运动的能力；稳定性是指汽车受到外力（如离心力、横向风力、道路纵横坡干扰力、路面附着系数变化等）扰动后’恢复原来运动状态的能力，也就是汽车抗翻车和侧滑的能力。汽车操纵性与稳定性两者密切相关，互为影响，通称汽车操纵稳定性。驾驶员驾车操作（除加速外）主要是通过转向、制动来实现的，     

汽车侧滑与处置

行驶的汽车因制动、转动惯性和其他原因,引发某一轴的车轮或两轴的车轮出现横向移动(即向侧面发生甩动)的现象,称为侧滑。汽车侧滑特别是后轮侧滑,对安全行车威胁较大,常造成碰撞、翻车、掉沟等恶性交通事故。据我国某省对驾驶员负主要责任的交通死亡事故的统计,因后轮侧滑而引发的事故占40%,其中,有50%是在驾驶员使用制动和转弯时发生的,对此,应引起高度重视。一、汽车侧滑的原因1.路面湿滑、油污或结冰等,其附着系数降低,且左右不对称,车轮载荷与路面附着力也跟着降低,稍有横向外力作用,就会引发车轮侧滑;2.制动时四轮受到的阻力不平衡,诸…     

林区冰雪道路上运材汽车的安全行驶

据以往的经验,林区在进入冬季运材季节以后,常常因为道路冰冻而发生运材汽车的滑溜翻车事故。为了保护职工和车辆的安全,促进林业生产建设的发展,笔者在对几年来翻车事故调查的基础上,提出几条防止翻车事故的安全措施,供有关方面参考。 冰雪道路车辆溜滑的主要原因 正常情况下,汽车发动机产生的动力传到车轮时,汽车轮胎与路面之间就要产生相应的反力。这个反力的大小,取决于轮胎与路面之间附着系数和负荷的大小。适当的负荷系数是汽车安全行驶所必须的一个条件。在一般情况下,林区运材公路干砂石路面附着系数为0.50～0.70。冰雪路面的附着系…     

汽车辅助制动装置发展综述

平均行驶速度和载重量的增加,要求车辆具有更大的制动效能,为了有效分流制动负荷常采用辅助制动系统.介绍国内外制动法规的发展和现状,排气辅助制动装置、发动机缓速器、电涡流缓速器和液力缓速器的结构、工作原理及各辅助制动装置的制动性能;比较各辅助制动装置的优缺点,有利于汽车制动技术的发展,全面提高汽车行驶安全性能;展望未来汽车辅助制动装置的两大发展趋势,一是电子控制技术在汽车制动上的应用,二是多种辅助制动装置的联合制动.     

汽车气压应急制动装置

汽车气压应急制动装置本刊讯一种用于防止汽车气压制动失灵的新型安全装置──ＷＴＹ１４０汽车气压应急制动装置，日前由北京铁石交通安全技术工程公司研制成功。这种应急制动装置兼有应急制动、行车制动、驻车制动三种功能。重载情况下有良好的防抱死功能，平顺性、稳定...     

解读汽车技术中的洋名词

安全科技和时尚名词 ABS,即防抱死制动系统,全称是Anti-lock Brake System,可安装在任何带液压刹车的汽车上。它是在全力刹车时利用电脑检测刹车是否锁死,在刹车锁死时迅速松开,形成高速点刹效果,使汽车在刹车时还有一定的方向控制力,避免车辆失控。     

汽车制动性动态测试装置设计及仿真分析

分析了汽车制动系统的技术要求和制动性能检测指标,及现有的制动性能检测方法和检测设备存在的问题,然后提出了动态检测系统的设计构想,并在理论上建立了汽车在该系统下制动时的动力学模型,用Matlab对该模型进行仿真,进一步说明在进行汽车制动性能检测时应检测汽车的动态轴重而非静态轴重,为汽车制动性能检测提供充分的理论依据。     

Driver-training and emergency brake performance in cars with antilock braking systems

The purpose of this study was to assess the effects of a two-day post-license driver-training program on brake performance in cars with antilock braking systems (ABS). A trainee group (n = 26) and a control group (n = 13) participated in the experiment. The trainee group were enrolled in a two-day training course that included instruction in a braking technique that may be used in cars with and without ABS. All participants performed emergency brake tests from 80 and 100 km h⁻¹ in an instrumented car before and after the training period. Results indicated the post-training group used a smoother braking profile, were less reliant on ABS activation, had enhanced postural stability, but took about one car length longer to stop from 100 km h⁻¹ compared with the control group. Implications of these results for braking in cars with and without ABS, and for driver education programs in general are discussed.     

Antilock Brake Systems and Risk of Different Types of Crashes in Traffic

While antilock braking systems (ABS) have been convincingly demonstrated to enhance test track braking performance, their effect on crash risk in actual driving remains less clear. This paper examines how ABS influences crash risk using mainly two published studies which used police-reported crashes. The published findings are augmented by including new data and additional results. All the work is based on seven General Motors (GM) passenger vehicles having ABS as standard equipment for 1992 models but not available for 1991 models. The ratio of crashes under an adverse condition (say, when the pavement is wet) to under a normal condition (say, when the pavement is dry) is compared for ABS and non-ABS vehicles. After correcting for such factors as model year effects not linked to ABS, the following associations between ABS and crash risk were found by averaging data from the five states Texas, Missouri, North Carolina, Pennsylvania and Indiana (the errors are one standard error): a (10 ± 3)% relative lower crash risk on wet roads compared to the corresponding comparison on dry roads; a (22 ± 11)% lower risk of a pedestrian crash compared to the risk of a non-pedestrian crash; a (39 ± 16)% increase in rollover crash risk compared to the risk of a non-rollover crash. Data from the same Ave states were used to examine two-vehicle rear-end collisions. Using the assumption that side-impact crashes estimate exposure, it was found that for wet roads ABS reduces the risk of crashing into a lead vehicle by (32 ± 8)%, but increases the risk of being struck in the rear by (30 ± 14)%. The results from this study and from all available reported studies are summarized in tabular form.     

永磁磁轨制动技术在轨道交通中的应用

介绍国外永磁制动技术在轨道交通中的应用情况;阐述旋转型永磁制动器和直线型永磁制动器的结构和工作原理;对永磁磁轨制动安装方式、控制方法、联合制动模式进行探讨。介绍了直线型永磁制动器的3种磁化形式:Halbach磁化、水平磁化和垂直磁化;运用准静态磁场分析方法,得出了各部分的磁场分布控制方程,矢量磁势A、磁感应强度B和涡流损耗的分布;从而得出了制动力的计算方法。实践证明永磁磁轨制动技术在轨道交通有着广阔的应用前景。     

矿井提升机盘闸制动系统工作状态监控与安全

运用故障树分析(FTA)方法分析矿井提升机盘式制动系统故障原因,包括机械故障、摩擦系数故障、液压故障等,提出矿井提升机盘闸制动系统的故障树,并给出了系统状态计算机测控系统方案。采用现代检测与计算机技术,对盘闸制动系统的主要故障进行综合检测;对摩擦系数进行间接检测;研究成果,为故障报警与控制提供了保障,报警与控制结合,提高了提升机盘闸制动系统的安全性。     

Does the improved stability offered by motorcycle antilock brakes (ABS) make sliding crashes less common? In-depth analysis of fatal crashes involving motorcycles fitted with ABS

Objective: This research investigated the following issue. Though several tests indicate that motorcycle ABS may increase motorcycle stability, thus reducing the risk of a sliding crash involving braking (i.e., the rider is separated from the motorcycle and slides along the road surface prior to collision), there is limited research showing to what extent sliding crashes are reduced by ABS in real-life conditions.

Methods: The Swedish Transport Administration (STA) and the Norwegian Public Roads Administration (NPRA) carry out in-depth studies for all road fatalities. A total of 38 in-depth studies with ABS motorcycles were included: 22 in Sweden and 16 in Norway (2005–2014). These were compared with 98 cases in Sweden and 32 in Norway involving motorcycles of the same types but without ABS. The data sets were analyzed separately and also merged together. The difference between the proportions of sliding crashes regardless braking was analyzed; selective recruitment was handled with a sensitivity analysis. Induced exposure was used to calculate the reduction of all crashes and those involving braking.

Results: Four ABS cases (11%) involved falling off the motorcycle prior to collision, and 35% of the non-ABS crashes were sliding (P =.004). The sensitivity analysis showed that the results were stable, with a relative difference of sliding crashes ranging between 65 and 78%.

None of the 4 sliding crashes with ABS occurred during braking; that is, all ABS riders who braked prior to collision crashed in an upright position. In the 4 sliding cases with ABS, the riders lost control of their motorcycles: 2 while accelerating on asphalt with very poor friction, 1 while negotiating a curve with an excessive lean angle, and 1 by abruptly releasing the throttle in the middle of a curve.

Although based on a limited number of cases, the distributions of sliding and upright collisions among crashes without braking were similar, thus suggesting that the crash posture would not be affected by ABS if no braking occurred. The calculations with induced exposure showed that upright crashes with braking were also reduced by ABS; all fatal crashes, regardless of braking, were reduced by 52%.

Conclusions: Though this research was based on a limited material, it confirmed that sliding fatal crashes are significantly decreased by ABS. Considering that ABS will soon be mandatory in the European Union on all new motorcycles with engine displacement over 125cc, these findings should be taken into account in the future design and testing of motorcycle-friendly road barriers and integrated protection systems.     

Autonomous emergency braking systems adapted to snowy road conditions improve drivers' perceived safety and trust

Objective: This study investigated drivers' evaluation of a conventional autonomous emergency braking (AEB) system on high and reduced tire–road friction and compared these results to those of an AEB system adaptive to the reduced tire–road friction by earlier braking. Current automated systems such as the AEB do not adapt the vehicle control strategy to the road friction; for example, on snowy roads. Because winter precipitation is associated with a 19% increase in traffic crashes and a 13% increase in injuries compared to dry conditions, the potential of conventional AEB to prevent collisions could be significantly improved by including friction in the control algorithm. Whereas adaption is not legally required for a conventional AEB system, higher automated functions will have to adapt to the current tire–road friction because human drivers will not be required to monitor the driving environment at all times. For automated driving functions to be used, high levels of perceived safety and trust of occupants have to be reached with new systems. The application case of an AEB is used to investigate drivers' evaluation depending on the road condition in order to gain knowledge for the design of future driving functions.

Methods: In a driving simulator, the conventional, nonadaptive AEB was evaluated on dry roads with high friction (μ = 1) and on snowy roads with reduced friction (μ = 0.3). In addition, an AEB system adapted to road friction was designed for this study and compared with the conventional AEB on snowy roads with reduced friction. Ninety-six drivers (48 males, 48 females) assigned to 5 age groups (20–29, 30–39, 40–49, 50–59, and 60–75 years) drove with AEB in the simulator. The drivers observed and evaluated the AEB's braking actions in response to an imminent rear-end collision at an intersection.

Results: The results show that drivers' safety and trust in the conventional AEB were significantly lower on snowy roads, and the nonadaptive autonomous braking strategy was considered less appropriate on snowy roads compared to dry roads. As expected, the adaptive AEB braking strategy was considered more appropriate for snowy roads than the nonadaptive strategy. In conditions of reduced friction, drivers' subjective safety and trust were significantly improved when driving with the adaptive AEB compared to the conventional AEB. Women felt less safe than men when AEB was braking. Differences between age groups were not of statistical significance.

Conclusions: Drivers notice the adaptation of the autonomous braking strategy on snowy roads with reduced friction. On snowy roads, they feel safer and trust the adaptive system more than the nonadaptive automation.     

滚筒式制动试验台检验能力的比对试验及评价

制动性能是机动车安全技术性能检验工作中的重要项目,多采用滚筒反力式制动试验台.该种台试检验方法的评价指标较多,重复性不好,且影响检测结果的因素各异,因此其检验能力的比对试验及评价困难.通过比对试验的实施,讨论确定了进行比对的检测参量,分析了车辆技术状况变化对比对的影响.然后,分别采用经典统计法和稳健统计Z比分数方法对滚筒台式制动性能比对试验数据进行处理,对计算结果进行了分析讨论,并就结果的评价问题进行了进一步的探讨.本研究有助于促进和提升机动车安全技术检验机构的检验工作,对于保障道路交通安全具有积极地意义.