擦亮生命安全的指示灯

福建漳州往龙岩的高速公路,有一段叫"和溪"的路段,该段高速公路因受山区地形限制,有连续14公里的长下坡,路形弯曲、复杂,路段纵坡度高达5.8%,临近长下坡坡度设计的极限。自通车以来,常有大型货车因下长坡制动失效,冲出路面,车毁人亡,因此被人     

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.     

汽车电涡流缓速器的特点及使用

行驶于山区丘岭地带经常上下坡的大中型汽车,由于车辆下坡时连续或频繁使用制动器,造成了制动鼓及摩擦片的快速磨损,情况严重的会发生制动器过热,制动鼓龟裂、制动蹄摩擦片烧蚀、轮胎受热稳定高等现象,导致制动效能下降。这样不仅降低了制动器和轮胎的使用寿命,严重时还影响行车安全。 随着汽车技术的不断进步,现在有     

电梯制动器制动响应时间抽检结果分析

本文介绍了检测电梯制动器制动响应时间的方法。该方法利用存储记录仪的两个测量通道同时检测制动器断电信号和制动器微动开关动作信号,通过比较两个信号间的时间差测得电梯制动器的制动响应时间。本文对电梯制动器制动响应时间专项抽查的结果进行了分析。发现在用电梯存在制动响应时间超标的情况,且制动器作为上行超速保护装置的部件,其制动响应时间远小于不作为上行超速保护装置部件的制动器。     

厂（场）内机动车辆液压制动系统常见故障诊断

在中华人民共和国国家标准《汽车制动系统结构、性能和实验方法》（GB12676—1999）中明确规定：“行车制动,不论车速高低、载荷多少、车辆上坡或下坡．行车制动必须能控制车辆行驶,切使车辆安全、迅速、有效地停住;行车制动必须是可控制的;必须保证驾驶员在其座位上双手无需离开方向盘就能实现制动。”但在现实生活中,机动车辆而因制动系统原因而发生的事故屡见不鲜。     

基于模糊综合评判的乘用车制动系统失效风险严重程度分析

为了准确评估乘用车制动系统失效风险严重程度,提高车辆行车安全,对我国汽车制动系统缺陷涉及的部件和失效模式进行了分析,并针对真空助力器和制动管路失效,设计、开展了实车试验。试验数据分析表明,在制动系统不同的失效状态下,平均制动减速度、制动距离和最大踏板力存在明显差异。因此将以上3个指标与制动系统失效模式结合构建事故树,确立了影响制动系统失效风险严重程度的指标体系;利用G1法和模糊综合评判法,得出了制动系统失效风险的严重程度。结果表明,制动系统真空助力器失效的严重程度等级为较高,制动管路泄漏的严重程度等级为高,与实际案例的风险严重程度评估结果一致。     

曳引电梯制动性能分析

电梯制动器是电梯重要的安全部件,因电梯制动性能不足,而造成的电梯事故屡有发生。但电梯制动器制动力并不是决定电梯制动性能的唯一因素,本文依据标准对电梯制动器制动性能的要求,通过建立简单的数学模型,对影响电梯制动性能的因素进行了分析。     

汽车防抱死制动系统性能的研究

汽车防抱死制动系统的性能直接关系到汽车的运行安全,笔者以获得汽车制动最佳效能并能自动适应路况变化为控制系统的设计目标;通过分析车轮制动的动力学原理;运用自寻最优控制理论;进行了基于路面附着系数的汽车防抱死制动系统设计。仿真实验结果表明:该控制系统能充分利用最大附着力制动、实现自动路面识别并可提高汽车制动时的操作稳定性;进而证实了基于路面附着系数的汽车防抱死制动自寻最优控制方法,相对以往的控制方法更为简单和更适合于实际应用。     

电梯制动器的安全与防护

电梯制动器一般由线圈、铁芯、制动推杆、制动臂、制动带、制动轮、制动弹簧、制动器底座等组成,所有参与向制动轮或盘施加制动力的制动器机械应分为两组装设,以避免一组部件失效时引起另一组失效从而引发事故。当然,制动器必须要有足够的制动力矩,以保证轿厢载有125％额定载荷并以额定速度向下时,操作制动器应能使曳引机停止运转。     

矿井制动系统中的计算机仿真应用

笔者以矿井提升机制动系统的制动器为研究对象,采用计算机仿真对其进行模拟。首先,对制动器的闸瓦位移和油压关系建立了数学模型;然后,通过计算机仿真模拟出位移-时间和油压-时间图,通过对系统的仿真可以直观地了解系统的工作性能,比如改变参数后系统的输出与实际是否相符,以使系统达到最优。仿真模拟的重点是模拟制动器的工作过程,当设定仿真参数与实际制动系统的参数相同时,检查仿真输出是否由于实际的输出一致,从而可以更有利于系统的改进和完善;同时在测试曲线中可以得到制动盘的偏摆、空动时间、闸瓦间隙等参数,这些都是影响制动器安全的重要因素,也是制动系统性能测定的重要内容。     

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。     

电梯制动器机械装置提起（或释放）验证的研究

为确保电梯制动器检测开关能够准确检测电梯制动器机械装置提起（或释放）的异常,消除异常造成的危险情况,结合电梯制动器的型式和检测开关的动作原理,对各种检测开关接线方式进行分析,针对制动器的型式提出了合理的制动器检测开关接线方式。研究结果表明:直压式制动器可用1个通断状态的检测开关对其机械装置的提起（或释放）进行验证,但应在电梯的主板上设置2个检测点;杠杆式鼓式制动器应用具备2个通断状态的检测开关对其机械装置的提起（或释放）进行验证,且应采用常开并联或常闭串联的方式检测制动器机械装置的释放,采用常闭并联和常开串联的方式检测制动器机械装置的提起。     

起重机两种制动器的比较与选用

介绍直流电磁铁式制动器和交流电力液压推杆式制动器各自的特点,并对它们的优缺点进行分析,提出了我厂对它们的选用情况。     

The effect of precrash velocity reduction on occupant response using a human body finite element model

Objective: The objective of this study is to use a validated finite element model of the human body and a certified model of an anthropomorphic test dummy (ATD) to evaluate the effect of simulated precrash braking on driver kinematics, restraint loads, body loads, and computed injury criteria in 4 commonly injured body regions.

Methods: The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant (M50-O) and the Humanetics Hybrid III 50th percentile models were gravity settled in the driver position of a generic interior equipped with an advanced 3-point belt and driver airbag. Fifteen simulations per model (30 total) were conducted, including 4 scenarios at 3 severity levels: median, severe, and the U.S. New Car Assessment Program (U.S.-NCAP) and 3 extra per model with high-intensity braking. The 4 scenarios were no precollision system (no PCS), forward collision warning (FCW), FCW with prebraking assist (FCW+PBA), and FCW and PBA with autonomous precrash braking (FCW + PBA + PB). The baseline ΔV was 17, 34, and 56.4 kph for median, severe, and U.S.-NCAP scenarios, respectively, and were based on crash reconstructions from NASS/CDS. Pulses were then developed based on the assumed precrash systems equipped. Restraint properties and the generic pulse used were based on literature.

Results: In median crash severity cases, little to no risk (<10% risk for Abbreviated injury Scale [AIS] 3+) was found for all injury measures for both models. In the severe set of cases, little to no risk for AIS 3+ injury was also found for all injury measures. In NCAP cases, highest risk was typically found with No PCS and lowest with FCW + PBA + PB. In the higher intensity braking cases (1.0–1.4 g), head injury criterion (HIC), brain injury criterion (BrIC), and chest deflection injury measures increased with increased braking intensity. All other measures for these cases tended to decrease. The ATD also predicted and trended similar to the human body models predictions for both the median, severe, and NCAP cases. Forward excursion for both models decreased across median, severe, and NCAP cases and diverged from each other in cases above 1.0 g of braking intensity.

Conclusions: The addition of precrash systems simulated through reduced precrash speeds caused reductions in some injury criteria, whereas others (chest deflection, HIC, and BrIC) increased due to a modified occupant position. The human model and ATD models trended similarly in nearly all cases with greater risk indicated in the human model. These results suggest the need for integrated safety systems that have restraints that optimize the occupant's position during precrash braking and prior to impact.     

Heavy Mining Vehicle Controls and Skidding Accidents

This paper examines various control locations in heavy mining vehicles. Three trucks have been tested on a skid pad in both clockwise and anticlockwise directions. The skid lengths were measured after each trial. The primary focus of the study was the positioning of various controls and their relevance to various skid lengths. Some additional measures such as NASA-TLX scales were also used to make subjective evaluations. The results are presented in this paper. The findings clearly indicate the relevance of control locations to actual skid lengths. The poorly located controls resulted in greater skid lengths. This is an important finding as skid lengths are related to greater reaction times in a skidding situation and hence greater risk of accidents on relevant trucks. Such accidents can incur large repair bills for damaged equipment whereas more importantly, jeopardizing the life and safety of heavy mining vehicle drivers.     

Assessment of Integrated Pedestrian Protection Systems with Autonomous Emergency Braking (AEB) and Passive Safety Components

Objective: Autonomous emergency braking (AEB) systems fitted to cars for pedestrians have been predicted to offer substantial benefit. On this basis, consumer rating programs—for example, the European New Car Assessment Programme (Euro NCAP)—are developing rating schemes to encourage fitment of these systems. One of the questions that needs to be answered to do this fully is how the assessment of the speed reduction offered by the AEB is integrated with the current assessment of the passive safety for mitigation of pedestrian injury. Ideally, this should be done on a benefit-related basis.

The objective of this research was to develop a benefit-based methodology for assessment of integrated pedestrian protection systems with AEB and passive safety components. The method should include weighting procedures to ensure that it represents injury patterns from accident data and replicates an independently estimated benefit of AEB.

Methods: A methodology has been developed to calculate the expected societal cost of pedestrian injuries, assuming that all pedestrians in the target population (i.e., pedestrians impacted by the front of a passenger car) are impacted by the car being assessed, taking into account the impact speed reduction offered by the car's AEB (if fitted) and the passive safety protection offered by the car's frontal structure. For rating purposes, the cost for the assessed car is normalized by comparing it to the cost calculated for a reference car.

The speed reductions measured in AEB tests are used to determine the speed at which each pedestrian in the target population will be impacted. Injury probabilities for each impact are then calculated using the results from Euro NCAP pedestrian impactor tests and injury risk curves. These injury probabilities are converted into cost using “harm”-type costs for the body regions tested. These costs are weighted and summed. Weighting factors were determined using accident data from Germany and Great Britain and an independently estimated AEB benefit. German and Great Britain versions of the methodology are available. The methodology was used to assess cars with good, average, and poor Euro NCAP pedestrian ratings, in combination with a current AEB system. The fitment of a hypothetical A-pillar airbag was also investigated.

Results: It was found that the decrease in casualty injury cost achieved by fitting an AEB system was approximately equivalent to that achieved by increasing the passive safety rating from poor to average. Because the assessment was influenced strongly by the level of head protection offered in the scuttle and windscreen area, a hypothetical A-pillar airbag showed high potential to reduce overall casualty cost.

Conclusions: A benefit-based methodology for assessment of integrated pedestrian protection systems with AEB has been developed and tested. It uses input from AEB tests and Euro NCAP passive safety tests to give an integrated assessment of the system performance, which includes consideration of effects such as the change in head impact location caused by the impact speed reduction given by the AEB.     

磁路形状对电磁制动器制动安全性的研究

电磁制动器是一种新开发的新型车用制动器,保证制动性能并对该制动器的关键部件电磁体进行优化设计十分重要。通过分析车辆制动过程中电磁制动器的工作机理,得到电磁体的受力与磨损状况,提出并设计了非轴对称准椭圆形电磁体磁路,采用Ansoft3D电磁场软件计算电磁力和磁密,选取合理磁密制作了样品。由仿真计算和试验表明,制动时工作平稳,磨损均匀,满足了特定制动器制动力及制动安全的要求,为开发不同型号的新型电磁制动器打下了基础。     

轨道门式起重机大车制动优化设计

针对门式起重机大车制动松弛,制动磨损严重、出轨翻车的问题,以某工厂轨道门式起重机为载体,设计了一种带大车匀减速防撞功能的门式起重机,介绍了基本结构和工作原理,通过在大车轨道两端设置一段安全刹车保护区域,压力传感器感应大车是否进入了安全保护区域而发车提醒信号,进而PLC控制单元整合处理采集到的压力信号和速度信号后控制制动器,制动器自动采取刹车减速措施,提高了门机的作业安全等级。当大车未进入安全保护区域时,大车制动器采用单独供电的方式,设置延时继电器,使大车断电运行一段距离后刹车制动,减少频繁调紧刹车,增强制动效果,提高门机吊装的稳定性和生产效率。     

制动器用电磁体的另一种非对称磁路设计

为了获得更好地制动安全性及延长制动器寿命,针对相关文献中制动器用电磁体磁路的非对称设计方案的不足之处,提出了新的磁路形状设计,即采用开槽的方法来获得要求的非对称磁路,并对此作了理论分析。由于磁路形状复杂,采用Ansoft软件中Maxwell-3D对设计的电磁体进行磁场及其吸力的仿真计算。对仿真结果和理论分析作了对比。以此制作的样品试验结果表明,电磁体工作姿态平稳,未发现因卡死而出现摩擦力的大幅度波动。且磨损均匀,满足了工作寿命的相关要求,为电磁制动器安全制动、延长工作寿命提供了保证。     

Effect of alcohol use on accelerating and braking behaviors of drivers

Objective: The present study examines the accelerating and braking behaviors of drivers at different blood alcohol concentrations (BACs) in heterogeneous driving conditions using driving simulator experiments.

Methods: Eighty-two licensed drivers performed simulated driving in a rural road environment designed in the driving simulator at 4 BAC levels: 0.00, 0.03, 0.05, and 0.08%. Driving performance was analyzed using vehicle control variables such as mean acceleration and mean brake pedal force. Generalized linear mixed models were developed to quantify the effect of different alcohol levels and explanatory variables such as driver’s age, gender, and other factors on the driving performance indicators.

Results: Alcohol use was reported as a significant factor affecting the accelerating and braking performance of drivers. The acceleration model results indicated that drivers’ mean acceleration increased by 0.013, 0.026, and 0.027 m/s² for BAC levels of 0.03, 0.05, and 0.08%, respectively. Results of the brake pedal force model showed that drivers’ mean brake pedal force increased by 1.09, 1.32, and 1.44 N for BAC levels of 0.03, 0.05, and 0.08%, respectively. Age was a significant factor in both the models where a 1-year increase in driver age resulted in a 0.2% reduction in mean acceleration and a 19% reduction in mean brake pedal force. Driving experience could compensate for the negative effects of alcohol to some extent while driving.

Conclusions: The findings of the present study revealed that drivers tend to be more aggressive and impulsive under the influence of alcohol, which deteriorates their driving performance. Impairment in accelerating and braking behaviors of drivers under the influence of alcohol leads to increased crash probabilities. The conclusions may provide reference in making countermeasures against drinking and driving and contribute to traffic safety.