四轮农用车转向系统设计【非断开式从动桥】【循环球式转向器】
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四轮农用车转向系统设计第一章 前 言1.1 四轮农用车的发展前景 中国改革开放以来,在农村实行家庭联产承包责任制的改革,使农村的经济空前的活跃。农村的货运量和人口的流动量急剧增加,加快运输机械化成为农村经济发展的迫切需要,正是这一市场的需要使具有中国特色的运输机械-农用运输车应运而生。它解决了农村运输的急需,填补了村际,乡际,城镇及城乡结合部运输网络的空白,活跃了农村经济,为农村富裕劳动力找了一条出路,从而使数以万计的农民走上了小康之路! 四轮农用运输车的竞争对手是轻型汽车。与汽车相比,四轮农用运输车有许多优点。入世后农用运输车没有受到多大冲击,因为它是中国特色的产业,符合国情,在国外几乎没人搞过。但是我们不能回避汽车与四轮农用运输车在市场的竞争,四轮农用运输车利用比较底的生产成本和微利经营的生产方式并引进先进的汽车技术,坚持“三低一高”的特色,注重产品质量,使之与在汽车行业的竞争中得以提高。随着党和国家提出的的开发西部的政策落实,也给农用运输车厂商带来了无限商机使农用运输车的开发有广阔的前景, 另一方面,我国有近13亿人口,特别是9亿以上的农村人口收入水平相对较低,需求量最大的是低档次的汽车。由于它比较适合中国国情,预计在未来的515年里,农用车在我国农村仍然具有广阔的发展前景。近年来农用车保有量增加很快,因此对柴油的需求很大。农用车制造工艺简单,价格便宜,其中三轮车价格在40007000元/辆,四轮车价格在11.5万元/辆,购车农户一般半年左右即可收回10000元投资。另外,农用车的养路费为每月每吨70元,是汽车的30%,使用成本为同吨位汽车的1/3到1/2。公路快速建设也促进了农用车的发展。旧中国,全国公路仅13104 km,而到1997年底,已达1.226106 km,目前全国98%的乡和80%的村都通了公路,使得农用车有用武之地。公安车管部门1993年制定了关于农用运输车道路交通管理的规定,在不损害管理大局的前提下,大幅度减少农用车的各种费用,免交车辆增容费。因此,在近十几年里我国农用车得到快速发展。1980年全国农用车产销量不足万辆,1992年产销量达到113万辆,首次超过当年汽车产销量(106.2万辆)。1998年农用车产销量达到270万辆,而同期汽车产销量为163万辆。我们要开发的农用运输车要采用设计理念,多进行优化设计,使产品新颖化,品种多样化以适应多种需要。首先农用运输车既然为农民服务,那么就必须立足于“农”字,需对农村市场有意的深入了解。及农村的道路,农民的使用水品和购买能力和分析研究!另外,过去研制一味的迎合用户“多拉快跑”的心理,盲目的加大强化车辆的部件是不可取的。农产品的开发研制该大则大,该小则小,不仅产品的档次要拉开,产品开发的大小两个方向也要拉开! 1.2 前桥和转向系组成和设计步骤前桥通过悬架与车架(或承载式车身)相联,两侧安装着从动午轮,用以在车架(或承载式车身)与车轮之间传递铅垂力、纵向力和横向力。从动桥还要承受和传递制动力矩。从动桥按与其匹配的悬架结构的不同,也可分为非断开式与断开式两种。从动桥按与之匹配的悬架结构不同可分为非断开式与断开式两种。由于农用车要求价廉,所以多采用非断开式前桥。非断开式的前桥主要有前梁,转向节和转向主销组成。一、从动桥结构形式1、非断开式转向从动桥2、合纵臂式后支持桥一般多采用非断开式转向从动桥。二、从动桥设计1、转向从动桥主要零件尺寸的确定,前梁,工字型断面,可采用常规设计,也可采用计算机程序可靠性优化设计。2、零件工作应力的计算(1)在制动工况下的前梁应力计算(2)在最大侧压力工况下的应力计算(3)转向节在制动和侧滑工况下的应力计算(4)主销和转向衬套在制动和侧滑工况下的应力计算(5)转向节推力轴承和止推垫片的计算三、转向系设计1、转向器方案分析2、转向器主要性能参数设计3、转向梯形的优化设计3第二章 概述2.1 前桥简介从动桥即非驱动桥,又称从动车桥。它通过悬架与车架(或承载式车身)相联,两侧安装着从动车轮,用以在车架(或承载式车身)与车轮之间传递铅垂力、纵向力和横向力。从动桥还要承受和传递制动力矩。 根据从动车轮能否转向,从动桥分为转向桥与非转向桥。一般汽车多以前桥为转向桥。为提高操纵稳定性和机动性,有些轿车采用全四轮转向。多轴汽车除前轮转向外,根据对机动性的要求,有时采用两根以上的转向桥直至全轮转向。 一般载货汽车采用前置发动机后桥驱动的布置形式,故其前桥为转向从动桥。轿车多采用前置发动机前桥驱动,越野汽车均为全轮驱动,故它们的前桥既是转向桥又是驱动桥,称为转向驱动桥。 从动桥按与其匹配的悬架结构的不同,也可分为非断开式与断开式两种。与非独立悬架相匹配的非断开式从动桥是一根支承于左、右从动车轮上的刚性整体横梁,当又是转向桥时,则其两端经转向主销与转向节相联。断开式从动桥与独立悬架相匹配。非断开式转向从动桥主要由前梁、转向节及转向主销组成。转向节利用主销与前梁铰接并经一对轮毂轴承支承着车轮的轮毂,以达到车轮转向的目的。在左转向节的上耳处安装着转向节臂,后者与转向直拉杆相连;而在转向节的下耳处则装着与转向横拉杆相连接的转向梯形臂。有的将转向节臂与梯形臂连成一体并安装在转向节的下耳处以简化结构。转向节的销孔内压入带有润滑油槽的青铜衬套以减小磨损。为使转向轻便,在转向节上耳与前梁拳部之间装有调整垫片以调整其间隙。带有螺纹的楔形锁销将主销固定在前梁拳部的孔内,使之不能转动。2.2 前桥各参数对汽车稳定性的作用与影响为了保持汽车直线行驶的稳定性、转向轻便性及汽车转向后使前轮具有自动回正的性能,转向桥的主销在汽车的纵向和横向平而内都有一定倾角。在纵向平面内,主销上部向后倾斜一个角,称为主销后倾角。在横向平面内,主销上部向内倾斜一个角,称为主销内倾角。主销后倾使主销轴线与路面的交点位于轮胎接地中心之前,该距离称为后倾拖距。当直线行驶的汽车的转向轮偶然受到外力作用而稍有偏转时,汽车就偏离直线行驶而有所转向,这时引起的离心力使路面对车轮作用着一阻碍其侧滑的侧向反力,使车轮产生绕主销旋转的回正力矩,从而保证了汽车具有较好的直线行驶稳定性。此力矩称稳定力矩。稳定力矩也不宜过大,否则在汽车转向时为了克服此稳定力矩需在方向盘上施加更大的力,导致方向盘沉重。后倾角通常在以内。现代轿车采用低压宽断面斜交轮胎,具有较大的弹性回正力矩,故主销后倾角就可以减小到接近于零,甚至为负值。但在采用子午线轮胎时,由于轮胎的拖距较小,则需选用较大的后倾角。主销内倾也是为了保证汽车直线行驶的稳定性并使转向轻便。主销内倾使主销轴线与路面的交点至车轮中心平面的距离即主销偏移距减小,从而可减小转向时需加在方向盘上的力,使转向轻便,同时也可减小转向轮传到方向盘上的冲击力。主销内倾使前轮转向时不仅有绕主销的转动,而且伴随有车轮轴及前横梁向上的移动,而当松开方向盘时,所储存的上升位能使转向轮自动回正,保证汽车作直线行驶。内倾角一般为;主销偏移距一股为3040mm。轻型客车、轻型货车及装有动力转向的汽车可选择较大的主销内倾角及后倾角,以提高其转向车轮的自动回正性能。但内倾角也不宜过大,即主销偏移距不宜过小,否则在转向过程中车轮绕主销偏转时,随着滚动将伴随着沿路面的滑动,从而增加轮胎与路面间的摩擦阻力,使转向变得很沉重。为了克服因左、右前轮制动力不等而导致汽车制动时跑偏,近年来出现主销偏移距为负值的汽车。前轮定位除上述主销后倾角、主销内倾角外,还有车轮外倾角及前束,共4项参数。车轮外倾指转向轮在安装时,其轮胎中心平面不是垂直于地面,而是向外倾斜一个角度 ,称为车轮外倾角。此角约为,一般为左右。它可以避免汽车重载时车轮产生负外倾即内倾,同时也与拱形路而相适应。由于车轮外倾使轮胎接地点向内缩,缩小了主销偏移距,从而使转向轻便并改善了制动时的方向稳定性。前束的作用是为了消除汽车在行驶中因车轮外倾导致的车轮前端向外张开的不利影响(具有外倾角的车轮在滚动时犹如滚锥,因此当汽车向前行驶时,左右两前轮的前端会向外张开),为此在车轮安装时,可使汽车两前轮的中心平面不平行,且左右轮前面轮缘间的距离A小于后面轮缘间的距离B,以使车轮在每一瞬时的滚动方向是向着正前方。前束即(B-A),一般汽车约为35mm,可通过改变转向横拉杆的长度来调整。设定前束的名义值时,应考虑转向梯形中的弹性和间隙等因素。在汽车的设计、制造、装配调整和使用中必须注意防止可能引起的转向车轮的摆振,它是指汽车行驶时转向轮绕主销不断摆动的现象,它将破坏汽车的正常行驶。转向车轮的摆振有自激振动与受迫振动两种类型。前者是由于轮胎侧向变形中的迟滞特性的影响,使系统在一个振动周期中路面作用于轮胎的力对系统作正功,即外界对系统输入能量。如果后者的值大于系统内阻尼消耗的能量,则系统将作增幅振动直至能量达到动平衡状态。这时系统将在某一振幅下持续振动,形成摆振。其振动频率大致接近系统的固有频率而与车轮转速并不一致,且会在较宽的车速范围内发生。通常在低速行驶时发生的摆振往往属于自摄振动型。当转向车轮及转向系统受到周期性扰动的激励,例如车轮失衡、端面跳动、轮胎的几何和机械特性不均匀以及运动学上的干涉等,在车轮转动下都会构成周期性的扰动。在扰动力周期性的持续作用下,便会发生受迫振动。当扰动的激励频率与系统的固有频率一致时便发生共振。其特点是转向轮摆振频率与车轮转速一致,而且一般都有明显的共振车速,共振范围较窄(35km/h)。通常在高速行驶时发生的摆振往往属于受迫振动型。转向轮摆振的发生原因及影响因素复杂,既有结构设计的原因和制造方面的因素如车轮失衡、轮胎的机械特性、系统的刚度与阻尼、转向轮的定位角以及陀螺效应的强弱等;又有装配调整方面的影响,如前桥转向系统各个环节间的间隙(影响系统的刚度)和摩擦系数(影响阻尼)等。合理地选择这些有关参数、优化它们之间的匹配,精心地制造和装配调整,就能有效地控制前轮摆振的发生。在设计中提高转向器总成与转向拉杆系统的刚度及悬架的纵向刚度,提高轮胎的侧向刚度,在转向拉杆系中设置横向减震器以增加阻尼等,都是控制前轮摆振发生的一些有效措施。 第三章 从动桥的结构形式3.1 总述各种车型的非断开式转向从动桥的结构型式基本相同,如图11所示。作为主要零件的前梁是用中碳钢或中碳合金钢的,其两端各有一呈拳形的加粗部分为安装主销的前梁拳部;为提高其抗弯强度,其较长的中间部分采用工字形断面并相对两端向下偏移一定距离,以降低发动机从而降低传动系的安装位置以及传动轴万向节的夹角。为提高其抗扭强度,两端与拳部相接的部分采用方形断面,而靠近两端使拳部与中间部分相联接的向下弯曲部分则采用两种断面逐渐过渡的形状。中间部分的两侧还要锻造出钢板弹簧支座的加宽文承面。有的汽车的转向从动桥的前梁采用组合式结构,即由其采用无缝钢管的中间部分与采用模锻成形的两端拳形部分组焊而成。这种组合式前梁适于批量不太大的生产并可省去大型缎造设备。转向节多用中碳合金钢模级成整体式结构。有些大型汽车的转向节,由于其尺寸过大,也有采用组焊式结构的,即其轮轴部分是经压配并焊接上去的。主销的几种结构型式如下图所示,其中比较常用的是(a),(b)两种。 (a) (b) (c) (d)图3-1主销结构形式(a)圆柱实心型 (b) 圆柱空心型 (c) 上,下端为直径不等的圆柱,中间为锥体的主销 (d)下部圆柱比上部细的主销 转向节推力轴承承受作用于汽车前梁上的重力,为减小摩擦使转向轻便可采用滚动轴承,例如推力球轴承、推力圆锥滚子轴承或圆锥波子轴承等。也有采用青铜止推垫片的。主销上、下轴承承受较大的径向力,多采用滑动轴承,也有采用滚针轴承的结构。后者的效率高,转向阻力小,且可延长使用寿命。3.2 农用车从动桥本设计为农用自卸车的转向前桥,因此应该本着耐用经济的思想进行方案的选择,为了降低生产成本,又在结构上满足要求的情况下应尽量简单。转向前桥有断开式和非断开式两种。断开式前桥与独立悬架相配合,结构比较复杂但性能比较好,多用于轿车等以载人为主的高级车辆。非断开式又称整体式,它与非独立悬架配合。它的结构简单,承载能力大,这种形式再现在汽车上得到广泛应用。因此本次设计就采用了非断开式从动桥。转向从动桥的主要零件有前梁,转向节,主销,注销上下轴承及转向节衬套,转向节推力轴承。前梁采用中间部分为无缝钢管与两端拳部组焊的形式。主销采用结构简单的实心的圆柱形如上图a所示。另外为了保证汽车转弯行驶时所有车轮能绕一个转向瞬时转向中心,在不同的圆周上作无滑动的纯滚动,本次设计有进行了转向梯形的优化设计。本方案转向梯形布置在前轴之后,进行梯形的最佳参数和强度计算。第四章 转向系的结构形式4.1 概述 汽车在行驶过程中,经常需要改变方向。就轮式汽车而言,改变行驶方向的方法是,驾驶员通过一套专设的机构,使汽车的转向桥上的车轮相对于汽车纵轴线偏转一定角度。此时路面作用于转向轮上的向后的反力就有了垂直与车轮的分量并成为汽车作曲线运动的向心力。在汽车直线行驶时,往往转向轮也会受到路面侧向干扰力的作用,自动偏转而干扰行驶方向。此时,驾驶员也可以利用这一套机构使转向轮向相反的方向偏转,从而使汽车恢复原来的行驶方向。这一套用来改变或恢复汽车行驶方向的专设机构即称作汽车的转向系。 转向系可按转向能源的不同分为机械转向系和动力转向系两大类。在现代汽车结构中,常用机械式转向系。机械式转向系依靠驾驶员的手力转动方向盘,经过转向器和转向传动机构使转向轮偏转。有些汽车装有防伤机构和转向减振装置。还有一些汽车的专门装有动力转向机构,并借助此机构来减轻驾驶员的手力,以降低驾驶员的劳累程度。对转向系的主要要求有:一、操纵轻便。转向时加在方向盘上的力对轿车不超过200N,对中型货车不超过360N,对中型货车不超过450N,方向盘的回转圈数要少。二、工作安全可靠。三、在转向后,方向盘有自动回正能力,能保持汽车有稳定的直线行驶能力。四、在前轮受到冲击时,转向系传递反向冲击到方向盘上要小。五、应尽量减小转向系统连接处的间隙,间隙应能自动补偿即调整,除了设计应正确的选择导向轮的定位角外,转向盘在中间式的自由行程应当保证直线行驶的稳定性和转向盘相对导向轮偏转角的灵敏度。4.2转向器结构形式及选择一、类型 根据转向器所用传动副的不同,转向器有多种。常见的有循环球式球面蜗杆蜗轮式、蜗杆曲柄销式和齿轮齿条式等。转向器的结构形式,决定了其效率特性以及对角传动比变化特性的要求。选用那种效率特性的转向器应有汽车用途来决定,并和转向系方案有关。经常行驶在好路面上的轿车和市内用客车,可以采用正效率较高的、可逆程度大的转向器。二、特点效率高、工作可靠、平稳,蜗杆和螺母上的螺旋槽在淬火后经过磨削加工,所以耐磨且寿命较长。齿扇和齿条啮合间隙的调整工作容易进行。和其它形式转向器比较,其结构复杂,对主要零件加工精度要求较高。 蜗杆曲柄销式转向器角传动比的变化特性和啮合间隙特性变化受限制,不能完全满足设计者的意图。 齿轮齿条式转向器的结构简单,因此制造容易,成本低,正、逆效率都高。为了防止和缓和反向冲击传给方向盘,必须选择较大的传动比,或装有吸振装置的减振器。4.3 循环球式转向器结构及工作原理 循环球式转向器中一般有两级传动副。第一级是螺杆螺母传动副,第二级是齿条齿扇传动副。 转向螺杆的轴颈支撑在两个圆锥滚子轴承上。轴承紧度可用调整垫片调整。转向螺母的下平面上加工成齿条,与齿扇轴内的齿扇部分相啮合。通过转向盘转动转向螺杆时,转向螺母不转动,只能轴向移动,并驱使齿扇轴转动。为了减小转向螺杆和转向螺母之间的摩擦,其间装有小钢球以实现滚动摩擦。二者的螺旋槽能配合形成近似圆形断面轮廓的螺旋管状通道。转向螺母外有两根导管,两端分别插入螺母的一对通孔。导管内装满了钢球。两根导管和螺母内的螺旋管状通道组合成两条各自独立的封闭的钢球流道。转向器工作是两列钢球只是在各自封闭的流道内循环,而不脱出。转向螺母上的齿条式倾斜的,因此与之啮合的齿应当是分度圆上的齿厚沿齿扇轴线按线性关系变化的变厚齿扇。因为循环球转向器的正传动效率很高,操作轻便,使用寿命长。经常用于各种汽车。综上最后本次设计选定循环球式转向器。第五章 转向桥的设计计算5.1 从动桥主要零件工作应力的计算主要是计算前梁、转向节、主销、主销上下轴承(即转向节衬套)、转向节推力轴承或止推垫片等在制动和侧滑两种工况下的工作应力。绘制计算用简图时可忽略车轮的定位角,即认为主销内倾角、主销后倾角,车轮外倾角均为零,而左右转向节轴线重合且与主销轴线位于同一侧向垂直平面内。如下所示:图 51转向从动桥在制动和侧滑工况下的受力分析简图1-制动工况下的弯矩图 2-侧滑工况下的弯矩图制动工况下的前梁应力计算:制动时前轮承受的制动力和垂直力传给前梁,使前梁承受弯矩和转矩。考虑到制动时汽车质量向前,转向桥转移,则前轮所承受的地面垂直反力为: (5-1) 式中:汽车满载静止于水平路面时前桥给地面的载荷,N;汽车制动时对前桥的质量转移系数,对轿车和载货汽车的前桥可取1.5;质量分配给前桥35%;=0.3588551.5=6641.25前轮所承受的制动力 式中:轮胎与路面的附着系数取为0.6;=6641.250.6=3984.75 N由于和对前梁引起的垂向弯矩和水平方向的弯矩在两钢板弹簧座之间达最大值,分别为: Nmm (5-2) Nmm (5-3)式中:见图31,取=285 mm车轮(包括轮毅、制动器等)所受的重力,N;取=980N;B前轮轮距取B=1320 mm;S前梁上两钢板弹簧座中心间的距离取为550 mm则 =2179581.25 Nmm=1534128.75 Nmm制动力还使前梁在主销孔至钢板弹簧座之间承受转矩T:T= Nmm式中:轮胎的滚动半径取为373.425 mm则有 T=3984.75373.425=1488005.269 Nmm前梁在钢板弹簧座附近危险断面处的弯曲应力和扭转应(单位均为MPa)分别为: (5-4) (5-5)式中: W 前轴弯曲截面系数,W=。前梁应力的许用值为=300500 MPa,当取D=68 mm ,d=58 mm时,W=11714.2=2643533.9 Nmm =225.67=300MPa故D=68 mm ,d=58 mm满足使用条件。5.2 在最大侧向力(侧滑)工况下的前梁应力计算当汽车承受最大侧向力时无纵向力作用,左、右前轮承受的地面垂向反力和 与侧向反力,各不相等,前轮的地面反力(单位都为N)分别为: 式中:汽车质心高度取为840 mm;车轮与地面附着系数取为0.3;此时,向右作用。则有: 侧滑时左、右钢板弹簧对前梁的垂直作用力为: 式中: 满载时车厢分配给前桥的垂向总载荷 板簧座上表面离地高度 取400mm=12399.8=12142.2N; 则有 5.3 转向节在制动和侧滑工况下的应力如图42所示,转向节的危险断面在轴径为的轮轴根部即III-III剖面处。 图52 转向节,主销及转向节衬套的计算用图一、在制动工况下IIIIII剖面处的轴径仅受垂向弯矩和水平方向的弯矩而不受转矩,因制动力矩不经转向节的轮轴传递而直接由制动底板传给在转向节上的安装平面。这时的,及IIIIII剖面处的合成弯矩应力(MPa)为: (5-6) (5-7) = (5-8)式中:转向节的轮轴根部轴径取为45mm,=30 mm,=550 MPa,则 =22.7Mpa550Mpa转向节采用30Cr,40Cr等中碳合金钢制造,心部硬度HRC241285,高频淬火后表面硬度HRC5765,硬化层深1.52.0mm。轮轴根部的圆角液压处理。二、在侧滑工况下在侧滑时左、右转向节在危险断面IIIIII处的弯矩是不等的,可分别按下式求得: 因此左右转向节都符合要求。5.4 主销与转向节衬套在制动和侧滑工况下的应力计算在制动和侧滑工况下,在转向节上、下衬套的中心,即与轮轴中心线相距分别为c,d的两点处,在侧向平面(图52(c)和纵向平面(图52(d)内,对主销作用有垂直其轴线方向的力。一、在制动工况下 地面对前轮的垂向支承反力所引起的力矩,由位于通过主销轴线的侧向平面内并在转向节上下衬套中点处垂直地作用于主销的力所形成的力偶矩(c+d)所平衡(见图52(b),故有 N 式中取95,c取57,d取62 mm;制动力矩由位于纵向平面内并作用于主销的力所形成的力偶(c+d)所平衡(见图52(c)。故有而作用于主销的制动力,则由在转向节上下衬套中点处作用于主销的力,平衡(见图52(c),且有:N由转向桥的俯视图(图52(d)的下图)可知,制动时转向横拉杆的作用力N为:N=力N位于侧向平面内且与轮轴中心线的垂直距离为(取为80 mm)如将N的着力点移至主销中心线与轮铀中心线的交点处则需对主销作用一侧向力矩N (见图42(b)。力矩N由位于侧向平面内并作用于主销的力偶矩所平(c+d)衡,故有而力N则内存整向节上下衬套中点处作用于主销的力,所平衡,且有:=由图52(b)可知,在转向节上衬套的中点作用于主销的合力和下衬套的中心作用于主销的合力分别为: (5-9) = =11912.88N (5-10)=16878.59N由上两式可见,在汽车制动时,主销的最大载荷发生在转向节下衬套的中点处,其值为=16878.59N二、在侧滑工况下 仅有在侧向平面内起作用的力和力矩,且作用于左右转向节主销的力是不相等的,它们可分别按下式求得: 取中最大的作为主销的计算载荷N,计算主销在前梁拳部下端面应力和剪切应力: MPa ; (5-11) MPa; (5-12)式中:主销直径取为25 mm; h 转向节下衬套中点至前梁拳部下端面的距离,见图52(a),取h=28mm; ; 50mm 故不发生干涉。4.运动干涉校核和纵拉杆长度的确定(参看图6-5) 已知钢板长度L=900mm钢板板簧拱高h=100mm吊耳中径e=39mm吊耳中心到相邻U型螺栓之距Le=404.5mm(两U型螺栓中心距91mm)通过做图求得B1A=510mm 图6-5 转向纵拉杆尺寸确定图6.2转向系的设计及参数确定转向系的效率功率: 从转向轴输入,经转向摇臂轴输出所求得的效率称为正效率,用符号表示,=(-)/;反之称为逆效率,用表示:=(其中 从转向轴输入功率 转向器中的摩擦功率作用在转向摇臂轴上的功率本车设计转向器为循环球式,其传动副之间用滚动摩擦代替滑动摩擦,如果忽略轴承和其它地方的摩擦损失,只考虑啮合副的摩擦损失,则:= (6-2)= (6-3)螺杆的螺线导程角 P摩擦角 f摩擦系数设计时取=,f=0.03,p=代入得: =82.1=78.3上两式表明:增加导程角正逆效率均增大.受增大的影响不宜过大,一般=,本车选用。6.3转向系计算载荷的确定转向系全部零件的强度,是根据作用在转向系零、部件上的力进行确定的。影响这个力的因素很多,如前轴负荷和路面阻力的变化等。驾驶员转向轮所需要克服的阻力,主要是车轮转动阻力、车轮稳定阻力和转向系中特别是在转向器和转向节中的摩擦阻力等所组成。通过将转向系中的滑动摩擦转变为滚动摩擦,可以使转向器和转向节内摩擦阻力减少到较小的程度。汽车在沥青或者混凝土路面上原地转向阻力矩:M= (6-4)M=402.9N.m式中 f轮胎和路面的滑动摩擦系数取0.7 G 前轴负荷 (8855N) p轮胎气压 0.21 MPa 作用在方向盘上的力为= (6-5)=167.4N200N ,满足设计要求。式中 转向摇臂长 参考同类车型为130mm 转向节臂长(110mm) 方向盘半径(200mm) 转向器的角传动比= 17.2 转向器的效率 i=* / 设方向盘在内车轮达到时的转角是则有/= i=* /,=36.4*110*17.2/130=529.76 /360=1.5圈d/2=6.350/2=3.175B=P-d=9.525-6.350=3.1752.5mm( 合格)图6-7 滚道结构形式导管内径d=d+e=6.350+0.65=7mm 导管壁厚取为1mm。四、接触角,以使轴向力和径向力分配均匀。五、齿条齿扇传动副设计设计参数参照是下表,一般将1-1中间剖面规定为基准剖面, 1-1剖面向右时,变位系数为正,向右时由正变零,再变为负。此时计算0-0剖面:表6-2齿扇参数表(0-0截面)分度圆直径D=mz=452mm齿顶高=m4mm齿根高=(5mm全齿h9mm齿顶圆直径60mm齿根圆直径42mm图6-8 齿扇剖面图齿扇轮在从轴线自左向右看是又窄又低的形状,变位系数逐渐增大,设0-0面与中间面1-1面的间距= 5mm,11截面: 由公式:=5=26-(1.0+0.25-0.14)=26+(1.0+0.25+0.14)4=31.56mm22截面:=(14+5)mm=26-(1.0+0.25-0.541)=26+(1.0+0.541)4=32.16mm33截面:=(-14+4.6)mm=26-(1.0+0.25+0.26)=26+(1.0-0.267)4=28.96mm分度圆处的齿厚:大端齿厚 =(+0.541)2=6.7mm小端齿厚 =(-0.26*tan22.5)*2=6.06mm齿条在与齿扇配合时,因齿扇为变厚齿扇,则满足啮合间隙特性,齿条变厚方向应与齿扇相反,齿条的齿扇与齿扇的齿槽宽相等。二者啮合为等移距变为齿轮啮合传动。六、循环球式转向器零件强度的计算为了进行强度计算,首先要确定其计算载荷,可利用汽车在干燥硬路面上作原地转向时转向轮的转向阻力矩,利用它可求的转向摇臂上得力矩和在转向盘上的切向力。他们均可作为转向系的最大载荷。钢球与滚道间的接触应力 =k (6-8)=1.615 =2334.49Mpa =2500MPa式中系数k由下式确定07 (6-9)查汽车设计表7-3取k=1.615r钢球半径滚道截面半径螺杆外半径E材料弹性模为2.1钢球与螺杆间正压力,可用下式计算=/ncoscos (6-10)=12418.72/(38*cos8*cos45)式中 接触角取螺杆螺线导程角取n参与工作的钢球数38作用在螺杆上的轴向力由以上可知接触应力可以满足要求。七、齿的弯曲应力:=540Mpa式中:F作用在齿扇上的圆周力F= M/=3662.73Nh齿扇的齿高b齿扇的齿宽 基圆齿厚=S /r-2r(inv-inv)=2*24.02/26-2*24.02*(0.02151448-0)=4.771mm(基圆齿厚的计算公式见机械原理课本)由上可知弯曲应力完全满足。螺杆与螺母用20CrMnTi刚材料制造,表面渗碳,深度为0.8-1.2mm,表面硬度为HRC58-63。第七章 转向梯形的优化设计 转向梯形机构用来保证汽车转弯行驶时所有车轮能绕一个瞬时转向中心,在不同的圆周上做无滑动的纯滚动。设计转向梯形的主要任务之一是确定转向梯型的最佳参数和进行强度计算。转向梯形有整体式和断开式两种。一般转向梯形机构布置在前轴之后,但当发动机位置很低或前轴驱动时,也有位于前轴之前的。 两轴汽车转向时,若忽略轮胎侧偏影响,两转向前轴的延长线应交于后轴延长线。设,分别是外内转向车轮转角,k为两主销中心线延长线到地面交点之间的距离,则梯形机构应保证内外转向车轮的转角有如下关系:ctg,若自变角为则因变角的期望值为:,现有转向梯形机构仅能满足上式要求。如下图所示,在图上作辅助虚线,利用余弦定理可推得转向梯形所绘出的实际因变角为:其中 m梯形臂长 梯形底角图7-1 汽车瞬时转向图应使设计的转向梯形所绘出的实际因变角尽可能接近理论上的期望值。其偏差最常使用的中间位置附近小转角范围应尽可能小,以减小高速行驶时轮胎的磨损。而在不经常使用且车速较慢的最大转角时可适当放宽要求,因此在加入加权因子构成评价优略的目标函数f(x)为: f(x)=将上式代得:f(x)=其中 x设计变量 x= 外转向轮最大转角,又上图可得:=其中 汽车最小转弯半径为5.5m, a主销偏移距为55mm, K=1320mm L=2600mm = 考虑到此时使用工况下转角小于,且100以内的小转角使用的更加频繁,因此取:当 建立约束条件时应考虑到:设计变量m及过小时,会使横拉杆上的转向力过大;当m过大时,将使梯形布置困难,故对m的上、下限及对的下限应设置约束条件。因越大,梯形越接近矩形f(x)值就越大,而优化过程是求f(x)的极小值,故可不必对的上限加以限制。综上所述,各设计变量的取值范围构成的约束条件为:m- 梯形臂长度m设计时常取在0.11K,0.15K梯形底角此外,由机械原理得知,四连杆机构的传动角不宜过小,通常取。如上图所示,转向梯形机构在汽车向右转弯至极限位置时达到最小值,故只考虑右转弯时即可。利用该图所作的辅助虚线及余弦定理,可推出最小传动角约束条件为 ,式中,为最小传动角。由上述数学模型可知,转向梯形机构的优化设计问题是一个小型的约束非线性规划问题,可用复合形法来求解。根据上述思路,可用C语言编程进行优化设计(原程序见附录)。优化的结果如下:转向梯形臂长m=160mm转向梯形底角 = 第八章 结 论 本设计参考汽车的转向从动桥和转向器多种结构形式而确定农用运输车转向从动桥及转向器的方案:主销采用实心圆柱形,前轴为中间是圆管的组焊形式,转向器采用循环球式。 并对其内部参数进行设计计算和对转向器零件强度进行计算,并最终设计出一个经济耐用的转向器。 车辆在制动和侧滑情况下,出现重量前移的现象,此时转向从动桥受力最大。因此本次设计在制动和侧滑两中工况下对前轴,转向节主销,转向节衬套,转向推力轴承进行应力校核。 前轴校核:前两钢板弹簧座附近断面处的应力最大,在此处校核其弯曲应力和扭转应力的大小。主销:在汽车制动时它的最大载荷发生在下转向节衬套的中点,对其进行校核。转向节衬套进行挤压应力校核。推力轴承进行最大当量载荷校核。转向梯形的优化设计保证了汽车转弯行驶时所有车轮能绕一个瞬时转向中心,车轮在圆周上作无滑动的纯滚动.然后编程对其优化设计。参考文献1 刘惟信.汽车设计.北京:清华大学出版社,20002 王望予.汽车设计(第三版). 北京:机械工业出版社,2000 3 陈家瑞.汽车构造(下册). 北京:机械工业出版社,20054 余志生.汽车理论(第三版) 北京:机械工业出版社,2000 5 张洪欣.汽车设计(第二版). 北京:机械工业出版社,1996 6 吴宗泽.机械设计实用手册. 北京:化学工业出版社,1999 7 自动车技术协会日.小林明.汽车工程手册. 北京:机械工业出版社,1996 8 刘鸿文.材料力学. 北京:高等教育出版社,19919 祖业发.工程制图.重庆:重庆大学出版社,2001 10 浙江交通学校.汽车构造教学图册.人民交通出版社,198611 徐灏.机械设计手册(3、4卷)北京:机械工业出版社,1991 12 陈军.汽车拖拉机转向梯形优化设计.西北农业大学学报,2000年,第7期,N0.1813 陈思忠.拖拉机与农用运输车, 2000年,第8期,N0.3214 安徽飞彩有限公司.农用运输车的发展趋势,2001年第3期,N0.1215 张武农.我国汽车工业创新的策略研究,2001年,第6期,N0.916 钱振为.汽车工业研究,2001年,第4期,N0.1717 阎荫棠.几何量精度设计与检测.北京:机械工业出版社,1996 致 谢本设计得到xxx等老师的亲切指导,在我的设计中,他们给我提出了许多不可或缺的指导,给了我莫大的启迪和自信!在此我对他们表示最崇高的敬意。 本设计组中的同学们给与我多方面的帮助,对此我对他们表示由衷的谢意。另外,我还对关心,支持该设计的老师同学深表谢意!恳请答辩尊师批评指正,不胜感激。 34附 录转向梯形优化设计源程序如下:#includemath.h#define HUDU 3.1415926/180main() float calculate(); floatm,k,L,fx,gm,gmmax,det,ctmax,resault3=0,0,150,h; int i; printf(enter L: ); scanf(%f,&L); printf(enter k: ); scanf(%f,&k); printf(enter gmmax: ); scanf(%f,&gmmax); printf(enter ctmax: ); scanf(%f,&ctmax); printf(enter det: ); scanf(%f,&det); for(i=0;i=1000;i+) m=(float)(rand()%(int)(15*k-11*k)/100+0.11*k; gm=(float)(rand()%(int)(10*gmmax-700)/10+70.000;h=(cos(det*HUDU)-2*cos(gm*HUDU)+cos(gm*HUDU+ctmax*HUDU)/(cos(det*HUDU)-cos(gm*HUDU)/cos(gm*HUDU)-2*m/k; if(h0) continue; fx=calculate(m,gm,k,L,ctmax); if(fxresault2) resault0=m; resault1=gm; resault2=fx; printf(the result is:nm=%f,fx%f,resault0,resault1,resault2); float calculate(m,gm,k,L,ctmax) float m,gm,k,L,ctmax; float a=0,b=0,c=0,d=0,fx=0,ct=1,sum=0; for(ct=1;ct0&ct=10&ct=20&ctctmax) sum=0.5*sum; fx+=sum; return(fx); System Overview Of Automobile Electric Power Steering Electric Power Steering system, EPS (Electric Power Steering, abbreviation) is a kind of rely on motor directly provide auxiliary torque of the Power Steering system, with the traditional HPS Hydraulic Power Steering system (Hydraulic Power Steering) compared to, EPS system has many advantages. EPS is mainly composed of torque sensor, speed sensor, motor, deceleration body and electronic control unit (ECU), etc. Development history of the development process of the car, the steering system has experienced four stages of development:From the initial mechanical Steering system (Manual Steering, MS) for the development of Hydraulic Power Steering system (Hydraulic Power Steering, referred to as HPS), then the electronically controlled Hydraulic Power Steering system (company Hydraulic Power Steering, the EHPS) and Electric Power Steering system (Electric Power Steering, hereinafter referred to as EPS).Mechanical steering system of automobile assembly, in the car parking and driving at low speed when the drivers steering load is too heavy, in order to solve this problem, the United States GM company pioneered in the 1950 s adopted the hydraulic power steering system on the car. However, hydraulic power steering system is unable to take into account the vehicle at low speed when the steering portability and high-speed stability, so in 1983, Japan Koyo company launched have speed induction function of electronically controlled hydraulic power steering system. This new type of steering system can provide decreased gradually with the increase of speed, steering, but complex, high cost, and cannot be overcome hydraulic system itself has many shortcomings, is a kind of between the hydraulic power steering and the transition between the electric power steering. In 1988, Japan Suzuki company first in the small car Cervo equipped with Koyo company research and development of steering power type electric power steering system; In 1990, the Japanese Honda company also adopted the independent research and development on the NSX sports cars of the rack power type electric power steering system, from then on, unveiled on auto electric power steering applications history. Type and advantages and disadvantages of our common power steering are mechanical hydraulic booster, electronic hydraulic power and electric power.The mechanical hydraulic boosterMechanical and hydraulic power is our one of the most common dynamical method, it was born in 1902, by the British Frederick w. Lanchester invention, and the earliest application is delayed for half a century later, the commercialization of the Chrysler 1951 mature hydraulic steering system is applied in the Imperial line disappears. Because the technology is mature and reliable, and low cost, has been widely spread.Mechanical hydraulic booster system main component of hydraulic pump, tubing, pressure fluid control valve, V belt, storage tanks, etc. This power is part of the engine power output into hydraulic pump pressure, auxiliary force on steering system, so that the tires.The electronic hydraulic pressure boostDue to mechanical hydraulic power consumption need sharp engine power, so people on the basis of mechanical hydraulic booster was improved, developed a more save energy consumption of electronic hydraulic power steering system. The system of the steering pump is no longer directly driven by the engine, but by the motor to drive, and on the basis of before equipped with the electric control system, make to the size of the auxiliary power is not only related to the steering Angle, also related to the speed. Mechanical structure increased hydraulic reaction equipment and flow distributing valve, the new electronic control system including the speed sensor, electromagnetic valve, steering ECU, etc.Electric powerEPS is the abbreviation of English for Electric Power Steering, Electric Power Steering system. Electric power steering system is the development direction of automobile steering system. The system provided by the electric power machine direct steering, eliminating the hydraulic power steering system required for the power steering pumps, hoses, hydraulic oil, conveyor belt and pulley mounted on the engine, save energy, and protect the environment. In addition, also has the easy, flexible assembly and under various conditions can provide steering characteristics. It is with these advantages, electric power steering system as a new steering technology, will challenge the everyone is very familiar with, have the hydraulic steering system with more than 50 years history.Driver in manipulation of the steering wheel steering, steering and steering wheel torque sensor detects the size of the torque, the voltage signal to the electronic control unit, the electronic control unit according to detect torque of the torque sensor voltage signals, the rotation direction and speed, etc., to the motor controller issued a directive, the motor output corresponding size and direction of the steering torque, thus generating auxiliary power. Cars dont turn, the electronic control unit is not issuing commands to the motor controller, motor does not work. Advantage advantages compared with traditional hydraulic power steering system, electric power steering system has the following advantages:1, only when the steering motor to provide power, can significantly reduce fuel consumptionTraditional hydraulic power steering system with the engine drives the steering pump, no matter to or not to consume power engine parts. And electric power steering system is powered by a motor in the steering, not to not waste energy. Therefore, the electric power steering system can reduce fuel consumption of the vehicle.Compared with hydraulic power steering system test shows that, when not to electric power steering can reduce fuel consumption by 2.5%; In turn, can be reduced by 5.5%.2, steering size can be adjusted by the software, to be able to take into account the steering portability and low speed when high speed steering stability, back is good performance.The traditional hydraulic power steering system provided by the steering size can change with the increase of speed. Although this makes the vehicle at low speed have good steering portability, but in high speed steering wheel is too light, have turned to FaPiao phenomenon, the driver without significant sense of road, reduce the stability of vehicle at high speed and the drivers sense of security.Electric power steering system provides convenient adjustment of size by software. At low speeds, the electric power steering system can provide larger steering, provide the vehicles steering portability; As speed increases, the electric power steering system to provide the steering can be gradually decreases, and turn to when the driver required to provide force will gradually increase, so the driver can feel obvious sense of road, enhances the stability of the vehicle.Electric power steering system can also exert certain additional back to positive torque and damping torque, making low speed when the steering wheel back to the middle position accurately, and can inhibit the high-speed rotating is steering wheel oscillation and overshoot in the process, both the return-to-center performance at high and low speed vehicles.3, compact structure, light quality, good production line assembly, easy to maintenanceCancelled the electric power steering system hydraulic steering oil pump, oil cylinder, hydraulic pipeline and oil tank, and the motor and deceleration institutions can make a whole, and the steering column and steering makes the entire steering system structure is compact, light quality, good on the production line of assembling, save time, easy to maintenance.4, through the program setup, easy to match with different models, electric power steering system can shorten the cycle of production and development.Because the electric power steering system has many advantages above, thus obtained is more and more widely used in recent years.Electric power steering system is on the basis of the mechanical steering system, install the motor and deceleration mechanism, torque Angle sensor, speed sensor and the electronic control unit (ECU) for ECU. Edit this section the characteristics of hydraulic power steering system has been developed for more than half a century, the technology has been quite mature. But with the development of the auto microelectronics technology, constantly improve to automobile energy saving and environmental protection requirement, the system of energy consumption and pollution to the environment may cause the inherent shortage is more and more obvious, cant completely meet the requirements of times development.Electric power steering system will be the latest power electronic technology and high performance motor control technology applied in automobile steering system, can significantly improve vehicle dynamic performance and static performance, enhance the drivers driving comfort and safety, reduce environmental pollution, etc. Once the system is put forward, therefore, is brought to the attention of many big car companies, and carry on research and development, the future of the steering system of electric power steering steering system will become mainstream, compared with the other steering system, the system highlights the advantage embodies in:A, reduce the fuel consumption.Engine to drive the hydraulic pump hydraulic power steering system, make the hydraulic oil flow ceaselessly, wasted energy. Instead of electric power steering system (EPS) only need to operation need motor provides energy, this energy can come from battery, also can come from the engine. Moreover, energy consumption is associated with the steering and the current speed of steering wheel. When the steering wheel does not turn, the motor doesnt work, need to start work under the influence of the motor in the control module and output the corresponding size and direction of the torque to produce power-assist steering torque, and the system output maximum steering torque, when the car spin with the change of the vehicle speed, output torque is also follow changes. The system realize the on-demand power, is the real on-demand power type (on demand) system. Car when starting a cold winter, the traditional hydraulic system response is slow, until after the hydraulic oil preheating can work normally. Because the electric power steering system design is not dependent on the engine and there is no hydraulic oil tube, is not sensitive to cold weather, the system can work even when to 40 , so provides quick cold start. Because the system does not start at the time of preheat, save the energy. Hydraulic pump is not used, to avoid the engine of parasitic energy loss, improve the fuel economy, and is equipped with electric power steering system of the vehicle and is equipped with hydraulic power steering system of vehicle contrast experiment shows that under the condition of not to, is equipped with electric power steering system of vehicle fuel consumption by 2.5%, in use to case, the fuel consumption was reduced by 5.5%.Second, strengthened to follow.In the electric power steering system, electric power machine attached directly to the steering mechanism can make the energy directly to the turning of the wheel. The system USES inertial shock absorber effect, make the reversal of the wheel and steering wheel shimmy water reducing greatly. So steering systems ability to resist disturbance greatly enhanced compared with the hydraulic power steering system, rotating torque generated by motor, without turning hysteresis effect of hydraulic power system, enhance the follow performance of steering wheel to the steering wheel.3, improve the steering characteristics are back.Until today, the development of the power steering system performance has reached the limit, the return-to-center characteristics of a electric power steering system has changed all that. When the driver to rotate the steering wheel Angle to loosen, the system can automatically adjust back to the middle of the wheel. The system also can let the engineers use software within the maximum adjustment to get the best design parameters are features. From low speed to high speed, and can get a bunch of return-to-center performance curve. Through flexible software programming and easy to get motor in various speed and torque under different shape features, the torque characteristics makes the system can significantly improve the steering ability, provides the steering is back to match the vehicle dynamic performance camera features. In the traditional hydraulic control system, to improve the features to be transformed mechanical structure of the chassis, it is difficult to implement.Fourth, improve the steering stability.Through to the car at high speed oversteering method to test stability characteristics of car. By using this method, high speed (100 km/h) of a cars on the corner of the excessive force it roll, in a short time since the return is in the process, the adoption of microcomputer control, makes the motor has higher stability and the driver feel more comfortable.5, provide flexible steering.Electric power steering system of the steering force from the motor. Through the software programming and hardware control, available to cover the entire speed variable steering force. Variable power shift depending on the size of the steering torque and speed. Whether parking, low speed or high speed, it can provide reliable, controllable good sense, and easier to yard operation.For traditional hydraulic system, variable steering torque is very difficult to achieve and the cost is very high, in order to get the variable steering torque, must add an additional controller and other hardware. But in the electric power steering system, variable steering torque are usually written to the control module, can be obtained through the rewrite of the software, and the required fee is very small.Six, adopting green energy, to meet the requirements of modern cars.Electric power steering system application of the cleanest power as an energy source, completely banned the hydraulic equipment, there is no leakage of liquid oil in the hydraulic power steering system problems, can say the system is complied with the era of green trend. The system because it has no hydraulic oil, no hoses, pumps and seals, avoid the pollution. Tubing and hydraulic steering system use polymer recycling, not easy to damage to the environment.Seven, system structure is simple, takes up the space is little, convenient layout, superior performance.Because the system has a good modular design, so dont need to redesign a different system, testing, processing, etc., not only save the cost, also for the design of different system offers great flexibility, and easier to assembly production line. Because there is no oil pump, tubing, and the pulley on the engine, allows engineers to design the system have more leeway, and the system control module, can design together and gear rack or separate design, very high space utilization ratio of engine parts. Saves the system installed on the engine belt pulley and the oil pump, set aside the space can be used to install other parts. Many consumers when buying a car is very concerned about the maintenance of vehicles. Cars with electric power steering system without oil pump, no hose connection, can reduce many worries. In fact, the traditional hydraulic steering system, hydraulic pressure oil pump and hose accidents accounted for 53% of the entire system failure, such as hose leakage and oil pump oil leak.Eight, assembly production line.Hydraulic system of electric power steering system has no need of pump, tubing, flow control valves, storage tanks and other components, the number of parts is greatly reduced, reducing the workload of assembly, save the assembly time, improve the assembly efficiency.Electric power steering system since the mid - 1980 - s since the early put forward, as the development direction of automobile steering system, will replace the existing mechanical steering system, hydraulic power steering system and electric control hydraulic steering system. Working principle of electric power steering system are as follows: first, the torque sensor to measure the pilot control torque on the steering wheel, the speed sensor to measure the current driving speed of vehicles, the then pass these two signal to ECU; ECU according to the built-in control strategy, calculates the ideal goal of steering torque, instruction for motor into current; Then, motor power torque by the retarding mechanism of amplification effect on the mechanical steering system, and the drivers manipulation of the moment overcomes the steering resistance moment together, realize the steering of the vehicle.Edit this section of the key technologies of electric power steering system key technology mainly includes two aspects of hardware and software.Mainly related to sensor, motor and ECU hardware technology. Sensor is the source of the whole system, and its accuracy and reliability is very important. Motor is the actuator of the system, its performance is good or bad determines the performance of the system. ECU is the operation center of the whole system, so the performance and reliability of the ECU is crucial.Software technology mainly includes the control strategy and fault diagnosis and protection of two parts. Motor control strategy is used to determine the current goals and track the current, make the motor output corresponding torque. Fault diagnosis and protection procedures used for the operation of the monitoring system, and alarm when necessary and some protection measures for its implementation. The working process of the electric power steering system (EPS) as a substitute for traditional hydraulic system products has entered into automobile manufacturing field. In contrast to the previous forecast, EPS is not only suitable for small cars, and some medium-sized cars are suitable for 12 v electric system installation. EPS system contains the following components: the torque sensor, the detection of steering wheel movement and the movement of vehicle; Electronic control unit, according to the torque sensor for signal of the size of the computing power; Electronic control unit (ECU) for motors, according to the torque output values formation; Produced by a reduction gear, and improve the motor power, and transmits it to the steering gear.Other vehicle system control algorithm input information is provided by the car CAN bus (for example, the steering Angle and vehicle speed, etc.). Motor driver also need other information, such as motor rotor position sensor (motor) and current (current sensor. Motor is controlled by four mosfets. Large with micro controller is not direct driving MOSFET gate capacitance, so need to using interfaces in the form of driver IC. For security reasons, the complete machine control system monitoring must be carried out. The motor control system integration on the PCB, usually contains a relay, the relay can be used as the main switch, in the case of a detected fault, disconnect the electrical and electronic control unit.Micro control unit (mu C) must be EPS control system with dc motor. Micro control unit according to the steering wheel torque sensor with the required torque information, forming a current control loop. In order to improve the safety level of system, the micro control unit shall have a board oscillator, so even in the case of external oscillator failure, can guarantee that the performance of the micro control unit, at the same time should also have on watchdog. Of infineon XC886 integrat
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