轿车麦佛逊式前独立悬架设计及有限元分析【含CAD图纸、PROE三维模型】
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毕 业 设 计（论 文）任 务 书 设计（论文）题目：轿车麦佛逊式前独立悬架设计及有限元分析 学生姓名： 发任务书日期：2015年12月30日 任务书填写要求 1毕业设计（论文）任务书由指导教师根据各课题的具体情况填写，经学生所在专业的负责人审查、系（院）领导签字后生效。此任务书应在毕业设计（论文）开始前一周内填好并发给学生。 2任务书内容必须用黑墨水笔工整书写，不得涂改或潦草书写；或者按教务处统一设计的电子文档标准格式（可从教务处网页上下载）打印，要求正文小4号宋体，1.5倍行距，禁止打印在其它纸上剪贴。 3任务书内填写的内容，必须和学生毕业设计（论文）完成的情况相一致，若有变更，应当经过所在专业及系（院）主管领导审批后方可重新填写。 4任务书内有关“学院”、“专业”等名称的填写，应写中文全称，不能写数字代码。学生的“学号”要写全号，不能只写最后2位或1位数字。 5任务书内“主要参考文献”的填写，应按照金陵科技学院本科毕业设计（论文）撰写规范的要求书写。 6有关年月日等日期的填写，应当按照国标GB/T 740894数据元和交换格式、信息交换、日期和时间表示法规定的要求，一律用阿拉伯数字书写。如“2002年4月2日”或“2002-04-02”。 毕 业 设 计（论 文）任 务 书 1本毕业设计（论文）课题应达到的目的： 本设计是对学生所学知识的检验，培养和提高独立分析问题和解决问题的能力；使学生受到科学研究、工程设计和撰写技术报告等方面的基本训练；提高学生对工作认真负责、一丝不苟,对事物能潜心考察、勇于开拓、勇于实践的基本素质。培养学生综合运用所学知识，结合实际独立完成课题的工作能力。对学生的知识面、掌握知识的深度、运用理论结合实际去处理问题的能力、实验能力、外语水平、计算机运用水平、书面及口头表达能力进行考核。 2本毕业设计（论文）课题任务的内容和要求（包括原始数据、技术要求、工作要求等）： 某轿车前悬所使用的是麦弗逊式独立悬架。麦弗逊式独立悬架有着结构简单、紧凑、占用空间小等众多优点，在现代轻型汽车中得到了广泛运用。 本毕业设计要求根据夏利某改型车的改型总体方案要求，对其前悬架进行设计计算。说明悬架中关键零部件如：螺旋弹簧、横向稳定杆、减振器等的设计、选型和校核。 整车性能参数 驱动形式 4 x 2前轮 轴距 2471mm 轮距前/后 1429/1422mm 整备质量 1060kg 空载时前轴分配负荷 60% 最高车速 180km/h 最大爬坡度 35% 制动距离（初速30km/h） 5.6m 最小转向直径 11m 最大功率/转速 74/5800kW/rpm 最大转矩/转速 150/4000Nm/rpm 轮胎型号 185/60R14T 变速器档位 手动5档 毕 业 设 计（论 文）任 务 书 3对本毕业设计（论文）课题成果的要求包括图表、实物等硬件要求： 1.设计说明书一份 2.图纸 悬架系统部分零件的二维零件图、装配图和三维装配图 4主要参考文献： 1林重博.夏利轿车悬架结构分析J.汽车研究与开发，1997，第5期 2林小明.汽车工程手册(第二分册)M.北京:机械工业出版社，1984. 3刘惟信.机械最优化设计M.北京:清华大学出版社，1994. 4陈立周，张英会，吴青一等.机械优化设计M.第1版.上海:上海科学技术出版社，1982. 5陈家瑞.汽车构造(下册) M.第三版.北京:人民交通出版社，1994. 6王望予.汽车设计M.第3版.北京:机械工业出版社，2000. 7余志生.汽车理论M.第2版.北京:机械工业出版社，1990. 8约森赖姆佩尔.悬架元件及底盘力学M.第1版.长春:吉林科学技术出版社，1992. 9 GP企画室.汽车车身底盘图解M.第1版，长春:吉林科学技术出版社，香港万里机构出版有限公司，1995. 10赵新红.麦弗逊悬架在车轮转向和跳动时的分析D:硕士学位论文.长沙:湖南大学,1997. 11刘子键，现代CAD设计基础M.长沙:湖南大学出版社,1999. 12蒋晓光，刘星荣 汽车独立悬架刚度计算方法质疑J 北京汽车 1999，第2 期 13马建军，徐国兴，童永 一种双横臂悬架侧倾中心的计算和分析J.合肥工业大学学报，1999，第4期第22卷 14曹立田，林颖，陈明宇.非独立悬架汽车转向轮运动分析J.机械设计与制造， 1998，第4期 15陆波.麦氏悬架系统运动分析J.汽车技术，1994，第6期 16许早龙.UG在麦克弗逊式前悬架运动分析中的运用J.计算机辅助设计与 制造，2001年，第3期 17王敏，周恒昌.微型汽车构造与维修(底盘及电器辑) M.第1版.北京:人民 交通出版社，1995年. 毕 业 设 计（论 文）任 务 书 5本毕业设计（论文）课题工作进度计划： 2015.12.05-2016.01.15确定选题，填写审题表；指导教师下发任务书，学生查阅课题相关参考文献、资料，撰写开题报告。 2016.01.16-2016.02.25提交开题报告、外文参考资料及译文、毕业设计（论文）大纲；开始毕业设计(论文)。 2016.02.26-2016.04.15具体设计或研究方案实施，提交毕业设计（论文）草稿，填写中期检查表。 2016.04.16-2016.05.05完成论文或设计说明书、图纸等材料，提交毕业设计（论文）定稿，指导老师审核。 2016.05.06-2016.05.13提交毕业设计纸质文档，学生准备答辩；评阅教师评阅学生毕业设计（论文）。 2016.05.13-2016.05.26根据学院统一安排，进行毕业设计（论文）答辩。 所在专业审查意见： 符合专业要求 负责人： 2016 年 2 月 19 日毕 业 设 计（论 文）开 题 报 告 设计（论文）题目：轿车麦佛逊式前独立悬架设计及有限元分析 2016 年 1 月 8 日 开题报告填写要求 1开题报告（含“文献综述”）作为毕业设计（论文）答辩委员会对学生答辩资格审查的依据材料之一。此报告应在指导教师指导下，由学生在毕业设计（论文）工作前期内完成，经指导教师签署意见及所在专业审查后生效； 2开题报告内容必须用黑墨水笔工整书写或按教务处统一设计的电子文档标准格式打印，禁止打印在其它纸上后剪贴，完成后应及时交给指导教师签署意见； 3“文献综述”应按论文的框架成文，并直接书写（或打印）在本开题报告第一栏目内，学生写文献综述的参考文献应不少于15篇（不包括辞典、手册）； 4有关年月日等日期的填写，应当按照国标GB/T 740894数据元和交换格式、信息交换、日期和时间表示法规定的要求，一律用阿拉伯数字书写。如“2004年4月26日”或“2004-04-26”。 5、开题报告（文献综述）字体请按宋体、小四号书写，行间距1.5倍。 毕 业 设 计（论文） 开 题 报 告 1结合毕业设计（论文）课题情况，根据所查阅的文献资料，每人撰写不少于1000字左右的文献综述： 1 悬架概述 1.1 悬架的定义及功用 悬架是汽车的车架(或承载式车身)与车桥(或车轮)之间的一切传力联接装置的总称。它有如下功用： 1) 联接车桥和车架 2) 缓冲不平路面对汽车产生的冲击力，衰减振动 3) 对车轮相对车身的跳动起导向作用。 1.2 悬架的组成 汽车悬架主要由弹性元件、减振装置和导向机构组成，此外，还辅设有横向稳定器和缓冲块。 1.2.1 弹性元件 汽车悬架中的弹性元件多指弹簧，用来实现车身与车轮之间的弹性联接，缓和路面冲击。主要有钢板弹簧、螺旋弹簧、扭杆弹簧、气体弹簧和橡胶弹簧等结构形式。现代轿车悬架多采用螺旋弹簧和扭杆弹簧，个别高级轿车则使用空气弹簧。 1.2.2 减振装置 减振器是产生阻尼力的主要元件，其作用是迅速衰减汽车的振动，改善汽车的行驶平顺性，增强车轮和地面的附着力。减振器上端与车身（或车架）相连，下端与车桥相连。目前汽车上使用最多的减振器主要是双向作用筒式减振器。 1.2.3 导向机构 导向机构是指上下摆臂等叉形钢架、转向节等元件，用来传递纵向力、侧向力和力矩，同时起导向作用,保证车轮相对于车架有确定的相对运动规律。 1.3 悬架设计的基本要求 对悬架提出的设计要求有： 1）保证汽车有良好的行驶平顺性。 2）具有合适的衰减振动的能力。 3）保证汽车具有良好的操纵稳定性。 4）汽车制动或加速时，保证车身稳定，减少车身纵倾，转弯时车身侧倾角要合适。 5）有良好的隔声能力。 6）结构紧凑，占用空间尺寸要小。 7）可靠的传递车身与车轮之间的各种力和力矩，在满足零部件质量要小的同时，还要保证有足够的强度和寿命。 2 悬架的结构分类 悬架按结构分大体可分为独立式悬架和非独立式悬架。 2.1 非独立悬架 非独立悬架的结构特点是：左、右车轮用一根整体轴连接，再经过悬架与车架(或车身)连接。非独立悬架系统具有结构简单、工作可靠、成本低廉、强度高、保养容易、行车中前轮定位变化小的优点，但由于其舒适性及操纵稳定性都较差，在现代轿车中基本上已不再使用，多用在货车和大客车上。 根据非独立悬架所用弹性元件不同，分为钢板弹簧、螺旋弹簧、空气弹簧、油气弹簧非独立悬架。 2.2 独立悬架 独立悬架的结构特点是：两侧是车轮各自独立地与车架或车身弹性联接，可独立跳动。其优点是：质量轻，减少了车身受到的冲击，并提高了车轮的地面附着力；可用刚度小的较软弹簧，改善汽车的舒适性；可使发动机位置降低，汽车重心也得到降低，从而改善汽车的行驶稳定性；左右车轮单独跳动，互不相干，能减小车身的倾斜和振动。但是独立悬架也存在着结构复杂、制造成本高、维修不便等缺点。现代轿车大都采用独立式悬架。 按其结构形式不同，独立悬架系统可分为横臂式、纵臂式、斜臂式、烛式及麦弗逊式独立悬架等。 3 麦弗逊式独立悬架 麦弗逊独立悬架是目前常见的一种独立悬架形式，大多应用在汽车前轮。 3.1 麦弗逊独立悬架的构造 麦弗逊式独立悬架主要由螺旋弹簧、减振器、横摆臂组成，绝大部分车型还会加上横向稳定杆。麦弗逊式独立悬架的物理结构为支柱式减振器兼作主销，承受来自于车身抖动和地面冲击的上下预应力，转向节则沿着主销转动；此外，其主销可摆动，特点是主销位置和前轮定位角随车轮的上下跳动而变化，且前轮定位变化小，拥有良好的行驶稳定性。在麦弗逊式独立悬架中，支柱式减振器除具备减振效果外，还要担负起支撑车身的作用，所以它的结构必须紧凑且刚度足够，并且套上螺旋弹簧后还要能减振，而螺旋弹簧弹簧与减振器一起，构成了一个可以上下运动的滑动立柱。横摆臂的作用是为车轮提供横向支撑力，并能承受来自前后方向的预应力。车辆在运动过程中，车轮所承受的所有方向的冲击力量就要靠支柱减振器和横摆臂这两个部件承担。 3.2 麦弗逊式独立悬架的优缺点 麦弗逊式独立悬架的优点是增大了两前轮内侧的空间，便于发动机及其一些部件的布置，且结构简洁，非簧载质量小，行驶平顺性较好。 其缺点是滑动立柱摩擦和磨损较大，且由于对侧向力没有足够的支撑力度，使得车辆在转向的时候车身有比较明显的侧倾，并且在刹车的时候有比较明显的点头现象。 3.3 麦弗逊式独立悬架在车型上的应用 麦弗逊式独立悬架是非常常见的悬架类型，在全球汽车市场都有非常广泛的应用。在国内市场，麦弗逊式独立悬架也是众多车型的首选悬架，其中最新应用麦弗逊前悬架的车型有上海通用别克新君威、新君越、北京现代IX35、一汽大众高尔夫6、比亚迪F0等车型，从这可以看出麦弗逊式独立悬架应用的广泛。 微型车、紧凑型车、中级车以及SUV车型上，也都能见到麦弗逊式独立悬架的身影，德国跑车的代表保时捷911全系也同样采用麦弗逊式独立悬架，这足以表现出麦弗逊式独立悬架应用之广。 毕 业 设 计（论文） 开 题 报 告 2本课题要研究或解决的问题和拟采用的研究手段（途径）： 1.课题研究的内容 1.针对汽车悬架系统的发展现状、主要类型及车辆应用情况等做详细综述，重点介绍麦弗逊式独立悬架的基本概况、主要特点和应用情况； 2.针对任务书中所给出的车型的原始参数，对这款车型的前悬架系统进行整体设计； 3.完成这款车型的麦弗逊式前独立悬架系统的零件设计，并对系统及其零部件进行设计方案的校核论证； 4.利用AutoCAD软件完成总装图中所有零件的二维设计图，及这款车型麦弗逊式前独立悬架的总装图。 5.利用Pro软件完成系统中三个关键零件的三维设计图； 6.利用ANSYS软件对其中至少一个关键零件（螺旋弹簧、减振器、横摆臂或横向稳定杆），进行简单的力学性能的有限元分析。 2.课题研究的手段 1.通过查阅相关资料了解麦弗逊式独立悬架的结构； 2.根据所给车型的原始参数，设计悬架零件； 3.运用Proe软件建立零件的三维模型； 4.利用ANSYS软件对其中至少一个关键零件，进行有限元分析 5.利用AutoCAD软件画出麦弗逊式独立悬架的总装图。 毕 业 设 计（论文） 开 题 报 告 指导教师意见： 1对“文献综述”的评语： 基本了解课题的研究及技术现状，明确主要研究内容及方法 2对本课题的深度、广度及工作量的意见和对设计（论文）结果的预测： 课题深度广度适中，工作量饱满，预计可以完成设计任务 3.是否同意开题： 同意 不同意 指导教师： 2016 年 03 月 04 日 所在专业审查意见： 符合专业要求 负责人： 2016 年 03 月 04 日 Advances in Automobile Engineering: Brake Assisted Differential Locking SystemAbstract“It takes 8,460 bolts to assemble an automobile, andone nut to scatter it all over the road.”Some of the biggest advances in the field of automotive technology in the past 10 years have come in the area of safety.Spurred by the improvements in the microprocessor speed,miniaturization, and software development, the automobile continues to evolve.In this new approach proposed, I am going to have an electronic and a pneumatic circuit to automatically control the traction of the vehicle.During ordinary conditions, when the vehicle is driven down a straight road, or if the difference between speeds of the two(rear) wheels is below a specified limit, no signal will be generated by the electronic circuit. This helps the vehicle negotiate the turns with better traction control as differential action is unaltered. But if the difference between speeds is beyond a specified limit, the signal will be generated by the electronic circuit which will actuate the pneumatic circuit. This causes gradual braking on the faster wheel until it gains traction.Hence, the wheels will never lose traction.This system ensures a reduction of more than 50% in the capital investment as compared to the already existing systems can tilt the scales in the favour of the manufacturing company and eventually the cost conscious consumer.Key words: Differential locking, traction control, Limited slip differential, pneumatic braking.I. INTRODUCTIONAre you really comfortable manoeuvring your vehicle through a muddy patch?In dry conditions, when there is plenty of traction, the amount of torque applied to the wheels is limited by the engine and gearing; in a low traction situation, such as when driving on ice, the amount of torque is limited to the greatest amount that will not cause a wheel to slip under those conditions. So, even though a car may be able to produce more torque, there needs to be enough traction to transmit that torque to the ground .As long as the tyre grips the road,providing a resistance to turning, the drive train forces the vehicle forward.Driveline torque is evenly distributed between the two rear drive axle shafts by the differential. When one tyre encounters a slippery spot on the road, it looses traction, resistance to rotation drops, and the wheel begins to spin. Because the resistance has dropped, the torque delivered to both the wheels changes. The wheel with good traction is no longer driven. If the vehicle is stationary in this condition, only the wheel over the slippery spot rotates. Hence the vehicle does not move. This situation places stress on differential gears. As the traction fewer wheels rotates at a very high speed, amount of heat generated increases rapidly, lube film breaks down, metal to metal contact occurs, and the parts are damaged. Now if the spinning wheel suddenly has traction, then the shock of the sudden traction can cause severe damage to the drive axle assembly.So presently how do we overcome these difficulties?To overcome these problems, differential manufacturers have developed the Limited Slip Differential. In automotive applications, a limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity. The main advantage of a limited slip differential is found by considering the case of a standard (or open) differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate at twice its intended velocity the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels. The clutch type LSD responds to drive shaft torque. The more drive shaft input torque present, the harder the clutches are pressed together and thus the more closely the drive wheels are coupled to each other.Limitations of the Limited Slip Differentiala) Heat dissipation leads to lube film breakage, metalto-metal contact occurs.b) If the friction lining of the energized clutch is damaged, the whole assembly has to be dissembled.c) High quality lubrication required.d) Due to presence of large number of mechanical components, reliability is less.e) As the speed increases, noise of vehicle also increases.f) Complicated and costly.II. PROPOSED INNOVATION-BRAKE ASSISTED DIFFERENTIAL LOCKINGSYSTEM (BADLS)In this new approach, there is an electronic and a pneumatic circuit to automatically control the traction of the vehicle. During the ordinary conditions, when the vehicle is driven down the straight road, or if the difference between the speeds of the two (rear) wheels is below a specified limit, no signal will be generated by the electronic circuit. This helps the vehicle negotiate the turns with better traction control, as the differential action is unaltered. But if the difference between the speeds is beyond a specified limit, the signal will be generated by the electronic circuit, which will actuate the pneumatic circuit. This causes gradual braking on the faster wheel until it gains traction. Hence, the wheels will never lose traction. The BADLS control module senses that a wheel is about to slip based on the input sensor data and in turn pulses the normally open inlet solenoid valve closed for that circuit.This allows fluid to enter the circuit. At the same time, the control module opens the normally closed solenoid valve for that circuit. This leads to the application of pneumatic pressure on the brake pads, leading to the artificial braking. Once the affected wheel returns to the same speed as the other wheel the control module returns both the valves to their respective normal positions releasing any residual pressure in the pneumatic circuit of the affected brake.Fig. 1 SCHEMATIC CIRCIUT OF BADLSWORKING:Normal Braking System Artificial Braking System(BADLS)When Slipping Take PlaceNormal Braking Condition When Speed Sensors Detect The Slipping ConditionBrake Control Valve ActuatedMicrocontroller Actuates Normally Opened Solenoid Valve2Microcontroller Actuates Normally Closed Solenoid Valve1 And Normally Opened Solenoid Valve2Solenoid Valve1 Remains InDefault Normally Closed StateArtificial Braking Is Applied To The Required Wheel By Flowing In The Auxiliary CircutAir Flows From Maste Cylinder Through The Main Circuit By Passing The Auxiliary Circut空气经主电路从主汽缸流出绕过辅助电路Fig. 2 WORKING OF THE BADLS CIRCUITFlowchart to explain working of the circuit shown in Fig 1 is given above in Fig 2. First flowchart shows working of normal breaking circuit and the latter shows the working when the badls circuit is working. During normal breaking condition solenoid valve 1 is in closed condition so air from master cylinder flows in main braking circuit bypassing the auxiliary circuit through solenoid valve 1 and thus normal breaking action is achieved. .In slipping condition microcontroller actuates normally closed solenoid valve and normally open solenoid valve 2 and thus artificial braking is applied to the required wheel.A. The BADLS Control moduleThe system is provided a control system, at least two driven wheels, a differential for transmitting power from the engine to the driven wheels and permitting relative velocity between the driven wheels. The control system includes two wheel velocity sensor, a comparator circuit and a control circuit. The wheel velocity sensor is configured to detect the angular velocity of the two driven wheels and to generate a signal. The comparator circuit is coupled to the wheel velocity sensor and is configured to compare the signals of the sensors and to generate a slip signal representative of the degree of slip of the driven wheels. The control circuit is coupled to the comparator circuit and to the brake assisted differential locking mechanism and is configured to generate control signals when a predetermined degree of slip occurs and to apply the control signals to the differential locking mechanism to limit relative velocity between the driven wheels.III. PROPOSED ARCHITECTURE FORBRAKE ASSISTED DIFFERENTIAL LOCKING SYSTEMThe control circuit shown below in Fig.3 is configured to receive signals representative of vehicle operating parameters (condition of slipping of wheels) and to generate control signals corresponding to the desired state of the brake assisted differential locking mechanism for limiting relative velocity between two driven wheels. Sensors are associated with the rear wheels. Control logic executed by the control circuit in a continuously cycled routine determines the desired state of the differential locking mechanism based upon the operating parameters.Fig. 3 PROPOSED ARCHITECTURE OF SYSTEMThe control circuit applies an appropriate control signal to the differential locking mechanism causing engagement or disengagement in accordance with the desired state. Wheel velocity sensor are configured to detect the velocity of the two rear wheels and to generate a wheel velocity signal given as an input to the micro controller. A comparator circuit of the micro controller is coupled to the wheel velocity sensors generate a slip signal representative of the degree of slip of the driven wheel. A control circuit is coupled to the comparator circuit and to the differentia locking mechanism and configured to generate control signals when a predetermined degree of slip occurs and to apply the control signals to the differential locking mechanism to limit relative velocity between the driven wheels by applying artificial braking by actuating the solenoid valves. The control circuit is further configured to disengage the differential locking mechanism when the degree of slip decreases to a level below a predetermined threshold. Wheel velocity sensor is provided for each of the driven wheels, each of the wheel velocity sensors being configured to generate wheel velocity signals and to apply the wheel velocity signals to the comparator circuit, and wherein the control circuit is configured to generate control signals for limiting relative velocity between the driven wheels when slip of any driven wheel exceeds a predetermined threshold value.IV. SPECIFICATIONS FOR ELECTRONIC COMPONENTS MICRO CONTROLLER ANALOG TO DIGITAL CONVERTER SIGNAL CONDITIONER1. Transistor2. DiodeA.MICROCONTROLLERUSE IN BADLS: The microcontroller input is the speed of the two wheel speed sensors. The microcontroller obtains the difference in between the two speed sensor outputs and compares it with the maximum allowable variation. If the variation is beyond the stipulated value, it activates the solenoid valves, thus enabling the auxiliary circuit, avoiding any slipping of the wheels.B.SOLENOID VALVEUSE IN BADLS: They act as ON/OFF switches and control flow of pressurized air into the Auxiliary Circuit. TYPE: Spool TypeC.ANALOG TO DIGITAL CONVERTERUSE IN BADLS: the analog speed signal from the wheel speed sensors is converted into the digital format by the ADC which is supplied as the input to the microcontrollerD. AIR BRAKING SYSTEMIn the air brakes simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected to a brake shoe, which can rub on the wheel, using the resulting friction to slow the train. The pressurized air comes from an air compressor and is circulated by a pneumatic line made up of pipes and hoses. In order to apply the braking force to the brake shoes, compressed air is used. An air brake system in general includes a compressor unit, air-reservoir tank, brake chamber and wheel mechanism.For maintaining adequate braking force at all times even whenthe engine is not running and air-reservoir tank is also necessary. To maintain air pressure, which is small air pump,is used.The compressor takes air from the atmosphere through the filter and the compressor air is sent to the reservoir through the unloader valve, which gets lifted at a predetermined reservoir pressure and relieves the compressor load. From the reservoir the air goes to the various accessories and also to the brake chambers also called the diaphragm units at each wheel, through the brake valve. The control of brake valve is with the driver who can control the intensity of breaking according to the requirements. The unloader valve in the air breaking system serves to regulate the line pressure.V.TESTING AND EVALUATION PARAMETERSThe system has been tested on a SAE BAJA test vehicle at the Automotive Research Association of India (ARAI), pune. This was done keeping in mind that this application would be really helpful for SAE BAJA teams who encounter conditions like slipping of wheels very often. Since vehicle slip is usually about 12-15% while turning, this microcontroller of the system has been designed to active at about 20% slip conditions and deactivates at about 5% slip. The system was tested successfully and the next step would be practical implementation in automobiles after some minor modification.The vehicle was jacked up on one wheel with the other wheel resting on ground surface .This was done to simulate the condition of maximum slipping. This condition will be present in actual conditions when vehicle is negotiating rocky terrain. The engine was started and accelerated. Due to one wheel being in air, the vehicle did not move forward and the jacked wheel rotated excessively. Now the solenoid was activated for the slipping wheel and artificial braking was provided. As a result the torque transmitting capacity of the wheels increases and consequently, the vehicle pulls over the rocks and gravel on the basis of the torque from the individual wheel.VI.COST COMPARISION TABLEAs can be seen from the above table that this system ensures a reduction of more than 50% in the capital investment as compared to the already existing systems.Table I. COMPARISON OF BADLS SYSTEM WITH EXISTING LSD SYSTEM IN THE MARKETEXISTING SYSTEMLIMITED SLIP DIFFERENTIAL(LSD)l TRD LSD Rs.60000l QUAIFE LSD Rs.70000TOTAL-RS 65000 or $1625PROPOSED SYSTEM1. OPEN DIFFERENTIAL ：Rs.200002. ELECTRONIC CIRCUIT ：Rs.10003. SPEED SENSORS ：Rs.75004. CHECK VALVE ：Rs.10005. SOLENOID VALVE ：Rs.1000TOTAL-RS 31000 or $750VII.ADVANTAGESa) Can be easily implemented in vehicles having pneumatic braking systems with slight modification.b) As electronic circuitry is used, response time, control and reliability are better than the existing systems.c) Low grade lubricants can be used as heat loss is reduced.d) Last but not the least; the system is economical and simple.VIII.LIMITATIONSThe overall efficiency depends on the combined efficiency of both the electronic as well as the pneumatic system.IX.APPLICATIONSThe system can be successfully incorporated in vehicles having pneumatic/hydraulic braking system, with a view to provide improves traction. It can be put to use in especially All Terrain Vehicles (ATV) and vehicles operating in high altitude areas (vehicles for military application) where snow causes excessive loss of traction. This system ensures a reduction of more than 50% in the capital investment as compared to the already existing systems which ensures the cost effectiveness of the endeavour.ACKNOWLEDGMENTSThe author is grateful to Prof. R.B.Patil, Head of Department,Army Institute of technology, India and Dr KC Vora at the Automotive Research Association of India, (ARAI) for their guidance and support.REFERENCES1 Jack Erjavec, Automotive Technology- A systems approach (Delmar Thomson Learning, 2000)2 T.K. Garrett, K.Newton, W.Steeds, the Motor Vehicle (Butterworth Heinmann, 2001)汽车工程的进步：微分锁刹车辅助系统摘要“要组装一辆汽车需要8460个螺栓，要把它全部撒在路上只需要一个螺母。”在过去十年里，汽车技术领域的一些最大进步已经发展安全。由于微处理器速度的提高、小型化和软件开发的刺激，汽车能够继续发展。在提出的这种新方法中，我将用一个电子电路和一个气压回路来自动控制车辆的牵引。在正常情况下，当车辆沿着直线道路行驶，或者两个(后)车轮的转速差低于限制值时，电子电路将不产生信号。这有助于车辆以更好的牵引力控制系统判定转向，因为微分动作是恒定的。但是，如果速度差超过指定限制时,电子电路将产生信号驱动气压回路，使渐进制动发生在速度更快的车轮上，直到它获得牵引力。因此，车轮将永远不会失去牵引力。和已经存在的系统相比，这个系统能确保减少超过50%的资本投资，可以使效益天平倾向于制造公司，并最终倾向于具有成本意识的消费者。关键词：微分锁；牵引力控制；防滑差速器；气压制动1 介绍当你操纵你的车通过一块泥泞的土地时，你真的感到舒适吗？在干燥条件下，当有足够的牵引力时，车轮的扭矩量被发动机和传动装置所限制；在低牵引力的情况下，例如在冰上开车时，扭矩量小于或等于最大值，不会导致车轮在这些情况下打滑。所以，即使一辆车可以产生更多的扭矩，仍然需要有足够的牵引力将扭矩传递到地面。只要轮胎抓住路面，提供一个转动阻力,传动系就能驱动车辆前进。动力传输线上的扭矩由微分装置均匀分配到两个后轮传动轴之间。当一个轮胎在路上遇到滑移点时，它会失去牵引力，旋转阻力下降，同时车轮开始旋转。因为阻力已经下降，传递给两车轮的扭矩就会改变。有足够牵引力的车轮将不再被驱动。如果在这种情况下车辆是静止的，那么只有在滑移点上的车轮能旋转。因此，车辆不能移动。这种情况强调了差速齿轮的重要性。随着牵引力变少，车轮以一个非常高的速度旋转，热量迅速增加，润滑油膜分解，金属与金属表面直接接触，造成接触部分损坏。现在，如果旋转的车轮突然获得牵引力，那么这种牵引力带来的冲击会在组成上对传动轴造成严重损坏。所以，目前我们如何克服这些困难呢？为了克服这些问题，差速器制造商开发了防滑差速器。在汽车应用中,防滑差速器(LSD)是差速齿轮装置的一种调整或派生类型，它允许输出轴存在转速差，但不允许速度差值增加并超出预设量。在一辆汽车中,这样的防滑差速器有时被用来代替标准差速器，他们能以更大的复杂性为代价，传达特定的动态优势。通过考虑在一个车轮完全没有接触地面的标准（或者“开放”)微分的情况下，防滑差速器的主要优势就被发现了。在这种情况下，接触的车轮保持静止，不接触的车轮以两倍预期的速度旋转。在两个车轮上传递的扭矩相等，但不会超过移动车辆所需的阈值扭矩，因此，车辆将保持静止。在典型道路上的日常使用中，这种情况并不太可能发生，因此正常的微分就足够了。但是，对于更高要求的使用，例如驾驶越野，或者高性能车辆，这种情况是不可取的，但是LSD可以解决这个问题。通过限制一对驱动轮的速度差，只需在至少一个车轮上获得些许摩擦，就可以传递有效的扭矩。离合器类型的LSD对驱动轴扭矩作出反应，驱动轴输入扭矩越多，离合器压合越困难，驱动轮被相互连接地更紧密。防滑差速器的劣势a)散热导致润滑油膜破损，金属和金属间的接触发生。b)如果离合器的摩擦片被损坏，整个组成必须被分解。c)要求高质量的润滑。d)由于存在大量的机械部件，可靠性变得更少。e)随着速度的增加，汽车的噪音也会增加。f)复杂并且昂贵。2 提出创新微分锁刹车辅助系统(BADLS)在这种新方法中，有一个电子电路和一个气压回路来自动控制车辆的牵引。在正常情况下，当车辆沿着直线道路行驶，或者两个(后)车轮的转速差低于指定值时，电子电路将不产生信号。这有助于车辆以更好的牵引力控制系统判定转向，因为微分动作是恒定的。但是，如果速度差超过指定限制时,电子电路将产生信号驱动气压回路，使渐进制动发生在速度更快的车轮上，直到它获得牵引力。因此，车轮将永远不会失去牵引力。微分锁刹车辅助系统(BADLS)的控制模块在输入传感器的数据基础之上，捕捉到车轮将要发生滑移的信号，反过来脉冲给该电路的常开进气电磁阀使其关闭，这允许液体进入回路。与此同时，控制模块打开回路的常闭电磁阀，使气压压力作用于刹车片，引起手动制动。一旦受影响的车轮速度和其他车轮速度相同，控制模块就让两个阀门回到他们各自的正常位置，在气压回路中释放剩余压力。Brake Pedal制动踏板Check Valve检测阀门Master Cylinder主缸Brake Wheel制 动 轮图1.BADLS电路示意图工作过程：正常制动系统 手动制动过程（BADLS）当滑移发生正常刹车情况当车速传感器检测到滑移状态驱动制动控制阀微控制器驱动常开电磁阀2微控制器启动常闭电磁阀1和常开电磁阀2电磁阀1保持默认的常闭状态手动制动经空气流入被应用于需要的车轮空气经主电路从主汽缸流出绕过辅助电路上面给出了解释
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