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The Track Vehicle Changes Direction Research Present Condition and DevelopmentTrends of The Organization1 change direction the research present condition of the organizationDifferent classification in basis method, the track vehicle changes direction organization can according to vehicle is in change direction process the power flows of deliver the way is divided into the single power flows to change direction the organization to flow to change direction the organization with a power, and also can according to in change direction process two the sport of side trackses have no the contact but is divided into the independent type change direction the organization with bad soon the type changes direction the organization.1.1 single powers establish a certain changing direction the organization after flowing change direction the single power in organization flow to change direction the general structure in organization method is at became soon the organization, is the most simple method to constitute track vehicle change direction to spread to move.The single power flows to change direction the organization to change direction the organization most in brief, among them most in common usely change direction the clutch, single bad soon the machine, double is bad soon the machine, planet changes direction organization etc.Change direction the clutch1,2 is all a friction that several types rub the clutch, depending the friction surface to deliver to turn the , being the separation some on changing direction the clutch laterally, can reduce or cut off that side drive a round delivers of turn the make vehicle changed direction.Change direction the size of the radius from drive a decrease for spreads to turn the measures namely the degree that clutch separate decides.Change direction the clutch is simple because of the construction, manufacturing convenience, got the extensive application on the small scaled track in inside in earlier period type tractor, bulldozer.But because its manipulate the sex bad, produce the efficiency low, can consume bigger, enlarge continuously along with the track vehicle power, change direction the application of the clutch will suffer certainly of restrict.SingleBad soon the machine changes direction the organization2,3 can make vehicle several why the speed of the center position still keeps in change direction process the original driving the car straightly is soon, being a When the complete system in side move, change direction the radius over small, but another side track speed over high, change direction the Cape speed over big, for this reason a power for needing changing direction power very bigly, would outrunning generally launching machine restrict, if the pilot keep on changing direction, have a little bit the immodesty and then will make launch the machine fire, as a result can depend to slip to whet, using than the greater half path changes direction, or pole is not fair and softly break to change direction continuously with the lesser half path.Therefore this kind of is single bad soon the machine change direction the organization to no longer adopt almost now.The speed that a speed for differing soon machine changing direction organization3,4 can making track vehicle at changing direction slowly soon side track lowering is equal to the fast side track the increment, the for this reason vehicle changes direction of average speed and straightly the speed that drive same alike.But because a variety for badly soon machine cant completely system moving first side track, vehicle cant originally changing direction, and changing direction radius scope has no usage to change direction the clutch big, changing direction the going smoothly worse.While changing direction, the fast side track accelerates, therefore launching the affixture of the machine carry the ratio adoption change direction the clutch big.The double is bad soon the machine be constituted by wheel gear of change direction the organization, with change direction the clutch compare the spare parts number little, bear to whet the sex good, the life span is longer.The planet changes direction the organization4,5 moves with the system from a planet a department the machine constitutes.The operation planet the system on the organization moves the machine can change two sides drives the round drives the dint size make vehicle changed direction.It is that type of to change direction the organization opposite in change direction the clutch change direction the organization can deliver the bigger changing direction the dint , can realize an athletic and fixed stalk wheel gear organization fall through of two free a planet for of flat-out decomposition with synthesizing, planet organization a three dollar as have the bad relating to soon; change direction the organization to much order to deliver the motive, and the internal path in organization faces the dint mutually equilibrium.But is complicated because of its construction, only industry in big power tractor, bulldozer and other heavy type vehicle last application.Single weakness that power change direction is obvious, vehicle only contain several fix of change direction the radius, press to rule not of change direction When the radius change direction, want to is slipped by friction a piece to whet to realize, and is hard to get the stability change direction the radius accurately; the next in order in change direction process rub a dollar piece of violent slip to whet to will bring to have fever with wear away, make spread to move the efficiency lower, especially in the big power change direction work appearance next, would exsit the bigger power lose, with the result that often need to be declined to change direction soon; moreover, the violent friction also make easy damage in organization, cause the work dependable bad, the life span lower.1.2 pairs of powerses flow to change direction the organization after launching machine, will launch the machine power be divided in to become soon with change direction two roads be juxtaposed to deliver, ising a double of powers to flow to change direction the organization.A power flows to change direction the organization will used for keeping the pushes forward of become soon the organization is different from result in leftly, the right side track speed differs of change direction the organization to be juxtaposed in spread move department, change direction the organization when the vehicle keeps the did not result in twoth the speed of side trackses are bad, while changing direction, became to flow each file of offering soon to drive the speed straightly with change direction the organization results in of two the speed of side trackses differ to remit to flow, realizing the vehicle change direction.(1)the machine type a power flow to change direction the organization to flow the foundation top that change direction the organization to appear at the earliest stage in the single power of was a machine to kept the with changed direction two powers flowed all from machinery to realized type a power to flowed to change direction the organization3.It is this kind to change direction the organization main from two become soon box( a lord become soon the box, a cent moves a box of), the planet wheel gear organization, clutch moves with the planet organization system the machine constitutes, the single power flows to change direction in changing direction function the organization has the very big increasing, but it still change direction the radius is to have the class.The file is more low, getting of change direction the radius more small; the file is more high, getting of change direction the radius more big.Cant still adapt to the vehicle road in all different curvatures on the tactful track that change direction to drive with the demand, also cant expel parts of coalescences rub a piece proceeds to slip to whet to change direction and from slip to whet an a series of problem for bringing.(2)the machine liquid press type a power flows to change direction the organization machineThe type of changes direction the organization changes direction the function easily under the influence of the pilots drivers technique, physical strength term moving the machine to wear away with the clutch, system, and bring the pilot the fatigue easily.Give or get an electric shock along with the machine the liquid press and technical development in engineering in machine in person, the machine type change direction the organization to will be eliminated on the big power tractor, bulldozer.etc. engineering vehicle necessarily.Press in the last additional liquid in system in machine the liquid of that pump the motor presses the machine liquid drives to press to change direction the system will get the application gradually.The machine liquid press type a power flows to change direction the organization5,6 from launch the machine and change the deal pump, control valve, fixed amount motor, many files become soon box and empress bridges change direction to differ to move the organization constitutes.It will spread to flow from the machine that launch the machine power in many files became soon the importation stalk of the box last cent flow, all the way flow through was pressed by liquid pump- liquid press motor constitute of change direction adjust soon system; another all the way flow through many files became soon box, finally experienced star row top confluence, then was lined up by planet of some a the parts( such as planet) spread to the vehicle to spread to move the stalk top eventually.Because the liquid presses to pump to press with the liquid the motor can have no the class controls, therefore using the this type of changing direction the organization since can acquire the carAn a lot of weakness for twoth lateral speeds differing realizing having no class controling, again overcoming machine type changing direction organization.If the liquid presses the motor do not work, only coming from central spread the dynamic power flow, the vehicle makes the straight line drives; if only have the liquid that come from the power press the motor flows, the vehicle can realize to change direction radius as the zero changing direction originally; if input at the same time two road powers flow, because the liquid presses the motor can realize to have no the class controls, for this reason vehicle two side tracks drive the rotation to have soon and will barely do much more endless, can get the much more endless changes direction the radius, can immediately realize to have no the class changes direction, pilot as long as manipulate to change direction the dish turns to move the liquid presses the device, can make vehicle driven along the certain arc stablely.This kind of changes direction the organization not only have the construction good, have no the friction a piece, life span is long, the efficiency is high and work dependable, arrange simple, maintain the adjustment little and lower to can consume to wait the characteristics the outside, but also it is not a motive to pass the part or cut off all a side track in working function to the system move a the side drives a the round realizes to change direction of, but two side tracks deliver the motive always, can realizes nicely like this the motive change direction, basic ascend a safety for slippery phenomenon, being applicable to proceeding being partial to carrying pushing soil with cutting off root homework; at sloping fields changing direction cant appearing conversing direction phenomenon, increases vehicle that dissolves the track; because of changing direction do not cut off the motive, the average car of the for this reason vehicle does not lower soon; the track do not stop driving, breaking to the soil little, in loosenning soft soil of pass the sex good; change direction the size of the radius can control arbitrarily, increasing the flexibility of the track vehicle, change direction steady; change direction vehicle can develop with drive the high work in same function straightly; realizes easily a the root manipulates the pole to control in to back with change direction.2 change direction the pure liquid in trend (1)in development in organization press to have no the class changes direction the organization wants to realize the track vehicle changes direction the radius can control and continue to have no the class changes of change direction the function, the adoption capacity type liquid presses to pump to press with the liquid motor etc. has no the class become soon a piece is a more realistic viable method.The pure liquid presses to change direction the organization7 9 of ss pass to pump of positive and negative two directions have no the class changes the deal regulates, realizing to launch the mobile dint was spread by double to move to change direction the road arrives to remit the popular star row has no the class changes of spreading and moving ratio, end realize the vehicle face or so two change direction laterally radius can continue to have no the class the variety keeps the , pass the liquid press to pump with the liquid press the motor shuts the lock( change the row that deal pump measureses for zero) to realize to change direction the zero to shut the lock axially, from but keeps to keep the stablely.Under the situation of becoming soon the organization hangs the blank on schedule to change direction, launch machine a power for sending out all to press from the liquid that change direction the road a piece deliver, can realize the vehicle change direction originally.The current liquid presses the industry level returns the hard getting the power enough and big and the good liquid in function presses a dollar an efficiency for, and the liquid presses the system low, this is the biggest obstacle that pure liquid press to have no the class change direction the technique develops.(2)the compound changes direction organization as to overcome the pure liquid presses the above blemish that change direction the organization, appearing now the small liquid in power in various adoptions press the liquid of a dollar piece presses the compound changes direction the project7.A pump a motor project: this project is to solves the liquid press the direct and the most simple project in shortage in a power in a dollar, its function press with pure liquid to change direction same, but two sets of liquids press a piece merge to make the organizations physical volume weight bigger, the efficiency is still lower.The machine liquid presses to reunite the project: that project is adopting a double of flowing the liquid press to change direction of at the same time, reserve a set of machines change direction the organization.Make use of the power not very of the liquid presses a dollar the piece realizes the greater half path changes direction of have no the class variety continuously; make use of the organization that machine change direction lesser half path realizes the class changes direction.This kind of change direction the organization falls through whole radius scope has no the class variety.A radius liquid presses to change direction the project: that project adoption contain two kinds of exportations soon the liquid that compare presses the motor, when the good road ascends to change direction adoption the higher exportation turns soon, native out of fix the hour then change to output with the low speed to overcome bigger changing direction the resistance.The liquid presses the liquid dint compound changes direction the project: that project presses with the liquid of the limited power a piece proceeds to have no the class changes direction, the help matches the machine accidentally at change direction the liquid press the motor dint not enough hour on time provide the help .That project although reduce the liquid press a piece efficiencies would be much lower.In fine, adopt the liquid press a dollar a point for having no class becoming soon characteristic to realizing track vehicle having no class changing direction is good choice, solving liquid pressing a dollar a power shortage then is low with the efficiency that direction is investigative.(3)the machine liquid presses the consecution has no the class changes direction the organization machine liquid presses the consecution has no the class changes direction the organization10 21 of ss are in simple liquid pressing cent in machine spreading the foundation that move the principle, adopting the different machine organization parameter combine, and press with liquid a dollar the piece matches with of a kind of latest model changes direction the organization.It can guarantee at continue to have no the class output the next applied small liquid in premise that turn to press the total power in an exportation for significantly increasing vehicle in a dollar soon, and its spread to move the efficiency far far ahead pure the liquid presses to change direction the organization spreads to move the efficiency.It represents the development direction that track vehicle change direction organization.The research develops the good machine in function liquid presses the consecution has no the class changes direction the organization, excellent turn to match the that type of turning. Construction parameter that face organization is the point lesson of the current vehicle engineering realm. 履带车辆转向机构的研究现状及发展趋势1、转向机构的研究现状依据不同的分类方法,履带车辆转向机构可根据车辆在转向过程中功率流的传递方式分为单功率流转向机构和双功率流转向机构,也可根据在转向过程中两侧履带的运动有无联系而分为独立式转向机构和差速式转向机构。1.1单功率流转向机构单功率流转向机构一般构造方法是在变速机构后串联某种转向机构,是构成履带车辆转向传动的最为简单的方法。单功率流转向机构是最简单的转向机构,其中最常用的有转向离合器、单差速器、双差速器、行星转向机构等。转向离合器都是多片式摩擦离合器,靠摩擦表面的摩擦力传递转矩,当分离某一侧的转向离合器时,就可以减少或切断该侧驱动轮所传递的转矩使车辆转向。转向半径的大小由驱动轮所传转矩的减少量即离合器分离的程度所决定。转向离合器由于结构简单、制造方便,在早期的中小型履带式拖拉机、推土机上得到了广泛运用。但由于其操纵性差、生产效率低、能耗较大,随着履带车辆功率的不断增大,转向离合器的应用将会受到一定的限制。单差速器转向机构可使车辆几何中心位置的速度在转向过程中仍保持原直线行驶车速,当一侧完全制动时,转向半径过小,而另一侧履带速度过高、转向角速度过大,因此所需转向功率很大,会超出一般发动机的功率限制,驾驶员若持续转向,稍有不慎就会使发动机熄火,因而只能靠滑磨,用较大半径转向,或极不平稳地以小半径断续转向。因此这种单差速器转向机构现在几乎不再采用。双差速器转向机构可使履带车辆在转向时慢速侧履带降低的速度等于快速侧履带增加的速度,因此车辆转向时的平均速度与直线行驶的速度相同。但由于双差速器不能完全制动一侧履带,车辆不能原地转向,且转向半径的变化范围没有使用转向离合器的大,转向平顺性较差。转向时快速侧履带加速,因此发动机的附加载荷比采用转向离合器的大。双差速器是由齿轮组成的转向机构,与转向离合器相比零件数目少、耐磨性好、寿命较长。行星转向机构由一组行星轮系和制动器组成。操作行星机构上的制动器可以改变两侧驱动轮驱动力矩大小使车辆转向。该类转向机构相对于转向离合器转向机构能传递较大的转向力矩,能够实现单自由度运动的固定轴齿轮机构所不能实现的二自由度的速度分解与合成,行星机构的行星架、太阳轮、齿圈三元件之间具有差速关系;转向机构多点传递动力,并且机构内部径向力相互平衡。但由于其结构复杂,仅在大功率的工业拖拉机、推土机及其它重型车辆上应用。单功率转向的缺点是明显的,车辆仅有几个固定的转向半径,按非规定的转向半径转向时,要靠摩擦元件的滑磨来实现,难以得到稳定准确的转向半径;其次是在转向过程中摩擦元件的剧烈滑磨会带来发热和磨损,使传动效率降低,特别是在较大功率的转向工作状态下,会存在较大的功率损失,以致常需降速转向;另外,剧烈的摩擦也使机构容易损坏,导致工作可靠性差,寿命降低。1.2双功率流转向机构在发动机后,将发动机功率分成变速和转向两路并列传递,就是双功率流转向机构。双功率流转向机构将用于直驶推进的变速机构与造成左、右侧履带速度差的转向机构在传动系中并列,转向机构在车辆直驶时不造成两侧履带的速度差,在转向时,变速流提供各档不同的直线行驶速度与转向机构造成的两侧履带的速度差汇流,实现车辆的转向。(1)机械式双功率流转向机构在单功率流转向机构的基础上最早出现的是直驶和转向两功率流均由机械装置来实现的机械式双功率流转向机构。此种转向机构主要由两个变速箱(一个主变速箱、一个分动箱)、行星齿轮机构、离合器和行星机构制动器组成,在转向性能上较单功率流转向机构有很大提高,但是它的转向半径仍然是有级的。档位越低,得到的转向半径越小;档位越高,得到的转向半径越大。仍然不能适应车辆在所有不同曲率的道路上用圆滑轨迹转向行驶的需要,也不能排除部分接合摩擦元件进行滑磨转向及由滑磨所带来的一系列问题。(2)机械液压式双功率流转向机构机械式转向机构的转向性能容易受到驾驶员的驾驶技术、体力条件和离合器、制动器磨损的影响,并且容易给驾驶员带来疲劳。随着机电液压及人机工程技术的发展,机械式转向机构必将会在大功率拖拉机、推土机等工程车辆上遭到淘汰。在机械系统上附加液压泵液压马达驱动的机械液压转向系统将逐渐得到应用。机械液压式双功率流转向机构由发动机、变量泵、控制阀、定量马达、多档变速箱以及后桥转向差动机构组成。它将由发动机传来的机械功率流在多档变速箱的输入轴上分流,一路流经由液压泵-液压马达组成的转向调速系统;另一路流经多档变速箱,最后在行星排上合流,然后经行星排中的某一部件(如行星架)传到车辆的终传动轴上。由于液压泵和液压马达可以无级控制,因此使用这类转向机构既可获得车辆两侧的速度差实现无级控制,又克服了机械式转向机构的许多缺点。若液压马达不工作,只有来自中央传动的功率流,车辆作直线行驶;若只有来自液压马达的功率流,车辆可实现转向半径为零的原地转向;若同时输入两路功率流,由于液压马达可实现无级控制,因此车辆两侧履带驱动轮转速差可以有无穷多个,可得到无穷多个转向半径,即可实现无级转向,驾驶员只要操纵转向盘转动液压装置,就可使车辆稳定地沿一定的圆弧行驶。这种转向机构不但具有结构性好、没有摩擦元件、寿命长、效率高、工作可靠、布置简便、维修调整少及降低能耗等特点外,而且在工作性能上它不是通过部分或全部切断一侧履带的动力来制动一侧驱动轮实现转向的,而是两侧履带始终传递动力,这样可很好地实现动力转向,基本上消除了履带的打滑现象,适用于进行偏载推土和切除树根作业;在坡地转向时不会出现“逆转向”现象,提高了车辆的安全性;由于转向时不切断动力,因此车辆的平均车速不降低;履带不停驶,对土壤破坏少,在松软土壤上的通过性好;转向半径的大小可任意控制,提高了履带车辆的机动性,转向平稳;转向时车辆能发挥
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