HGC1050輕型商用車轉(zhuǎn)向系統(tǒng)設(shè)計(jì)【說(shuō)明書(shū)+CAD】

HGC1050輕型商用車轉(zhuǎn)向系統(tǒng)設(shè)計(jì)【說(shuō)明書(shū)+CAD】,說(shuō)明書(shū)+CAD,HGC1050輕型商用車轉(zhuǎn)向系統(tǒng)設(shè)計(jì)【說(shuō)明書(shū)+CAD】,hgc1050,輕型,商用,轉(zhuǎn)向,系統(tǒng),設(shè)計(jì),說(shuō)明書(shū),仿單,cad 黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì)附 錄附錄ABasic Parts and Types of the Suspension and Steering SystemsSuspension System If a vehicles axles were bolted directly to its frame or body, every rough spot in the road would transmit a jarring force throughout the vehicle. Riding would be uncomfortable, and handling at freeway speeds would be impossible. The fact that the modern vehicle rides and handles well is a direct result of a suspension system.Even though the tires and wheels must follow the road contour, the body should be influenced as little as possible 1. The purpose of any suspension system is to allow the body of the vehicle to travel forward with a minimum amount of up-and-down movement. The suspension should also permit the vehicle to make turns without excessive body roll or tire skidding.Suspension System ComponentsVehicle Frame A vehicles frame or body must form a rigid structural foundation and provide solid anchorage points for the suspension system. There are two types of vehicle construction in common use today: body-over-frame construction, which uses a separate steel frame to which the body is bolted at various points and unibody construction, in which the body sections serve as structural members. Unibody construction is the most common, but body-over-frame construction is still used on pickup trucks and large cars.Springs The springs are the most obvious part of the suspension system. Every vehicle has a spring of some kind between the frame or body and the axles. There are three types of springs in general use today: leaf spring, coil spring, and torsion bar. Two different types of springs can be used on one vehicle. Air springs were once used in place of the other types of springs, but are now obsolete. Many modern vehicles have air-operated suspensions, but they are used to supplement the springs.Shock Absorbers When the vehicle is traveling forward on a level surface and the wheels strike a bump, the spring is rapidly compressed (coil springs) or twisted (leaf springs and torsion bars). The spring will attempt to return to its normal loaded length. In so doing, it will rebound, causing the body of the vehicle to be lifted. Since the spring has stored energy, it will rebound past its normal length. The upward movement of the vehicle also assists in rebounding past the springs normal length.The weight of the vehicle then pushes the spring down after the spring rebounds. The weight of the vehicle will push the spring down, but since the vehicle is traveling downward, the energy built up by the descending body will push the spring below its normal loaded height. This causes the spring to rebound again. This process, called spring oscillation, gradually diminishes until the vehicle is finally still. Spring oscillation can affect handling and ride quality and must be controlled.Air Shock AbsorbersSome suspension systems incorporate two adjustable air shock absorbers that are attached to the rear suspension and connected to an air valve with flexible tubing.Air operated shock absorbers have hydraulic dampening systems which operate in the same manner as those on conventional shocks. In addition, they contain a sealed air chamber, which is acted on by pressure from a height control sensor. Varying the pressure to the air chamber causes the air shock to increase or decrease its length or operating range.Air pressure is delivered to the air shocks through plastic tubing. The tubing connects the shocks to an air valve. Air pressure for raising the shocks is generally obtained from an outside source, such as a service station compressor, and is admitted through the air valve. To deplete the shocks of unwanted air (lower vehicle curb height), the air valve core is depressed, allowing air to escape.Control ArmsAll vehicles have either control arms or struts to keep the wheel assembly in the proper position. The control arms and struts allow the wheel to move up and down while preventing it from moving in any other direction. The wheel will tend to move in undesirable directions whenever the vehicle is accelerated, braked, or turned. Vehicle suspensions may have control arms only or a combination of control arms and struts. Types of the Suspension Front Suspension SystemsAlmost all modern front suspension systems are independent. With an independent suspension, each front wheel is free to move up and down with a minimum effect on the other wheel. In an independent suspension system, there is also far less twisting motion imposed on the frame than in a system with a solid axle. Nevertheless, a few off-road, four wheel drive vehicles and large trucks continue to use a solid axle front suspension. The two major types of independent front suspension are the conventional front suspension and the MacPherson strut front suspension.Conventional Front Suspension In the conventional front suspension system, one or two control arms are used at each wheel. In most systems, the coil springs are mounted between the vehicles frame and the lower control arm. In older systems, coil springs are mounted between the upper control arm and vehicle body. In a torsion bar front suspension system, the lower arm moves upward, it twists the torsion bar. Coil Spring Front Suspension Fig.11-1 shows a typical independent front suspension that uses rubber bushing control arm pivots. The top of the coil spring rests in a cup-like spot against the frame (unshown). The bottom of the coil spring is supported by a pad on the lower control arm. The top of each shock absorber is fastened to the frame; the bottom is attached to the lower control arm.Torsion Bar Front Suspension A torsion bar is located on each side of the frame in the front of the vehicle. The lower control arm is attached to the free end of the torsion bar. When the wheel is driven upward, the lower control arm moves upward, twisting the long spring steel bar.Macpherson Strut Front Suspension Most modern vehicles, especially those with front-wheel drive, use the MacPherson strut front suspension systems, Fig.11-2. Note that the MacPherson strut contains a coil spring, which is mounted on top of the heavy strut-and-pedestal assembly. The entire MacPherson strut assembly is attached to the steering knuckle at the lower part of the pedestal. The bottom of the MacPherson strut assembly is attached to the single control arm through a ball joint.The entire strut assembly turns when the wheel is turned. A bearing or thrust plate at the top of the strut assembly allows relative movement between the assembly and the vehicle body. The ball joint allows the strut assembly to turn in relation to the control arm. The strut contains a damper, which operates in the same manner as a conventional shock absorber. Most damper assemblies have a protective cover that keeps dirt and water away from the damper piston rod.The advantage of the MacPherson strut is its compact design, which allows more room for service on small car bodies. Solid Axle Front Suspension The use of the solid axle front suspension (or dependent suspension) is generally confined to trucks and off-road vehicles. This system uses a solid steel dead. Rear Suspension SystemsRear suspensions on vehicles with a solid rear axle housing generally utilize coil springs or leaf springs. When the vehicle has an independent rear suspension system, coil springs, MacPherson struts, a single transverse leaf spring, or even torsion bars can be used.Steering SystemThe steering system is designed to allow the driver to move the front wheels to the right or left with a minimum of effort and without excessive movement of the steering wheel. Although the driver can move the wheels easily, road shocks are not transmitted to the driver. This absence of road shock transfer is referred to as the nonreversible feature of steering systems.The basic steering system can be divided into three main assemblies:The spindle and steering arm assemblies.The linkage assembly connecting the steering arms and steering gear.The steering wheel, steering shaft, and steering gear assembly.Steering Gear The steering gear is designed to multiply the drivers turning torque so the front wheels may be turned easily. When the parallelogram linkage is used, the torque developed by the driver is multiplied through gears and is then transmitted to the wheel spindle assemblies through the linkage. On the rack-and-pinion steering system, the steering shaft is connected directly to the pinion shaft. Turning the pinion moves the rack section, witch moves the linkage. Late-model vehicles use either manual steering gears or power steering gears. There are three types of the steering gears in use: recirculating ball steering gear, worm-and-roller steering gear and rack-and-pinion steering gear.Power SteeringPower steering is designed to reduce the effort needed to turn the steering wheel by utilizing hydraulic pressure to bolster (strengthen) the normal torque developed by the steering gear. Power steering systems should ease steering wheel manipulation and, at the same time, offer enough resistance so that the driver can retain some road feel. Power steering is used with both conventional and rack-and-pinion systems (Fig.11-3).The self-contained steering gear contains the control valve mechanism, the power piston, and the gears. Pressure developed by the unit is applied to the pitman shaftThe power rack-and-pinion steering system also uses a rotary control valve that directs the hydraulic fluid from the pump to either side of the rack piston. An overall view of this setup is shown in Figure 11-3. Steering wheel motion is transferred to the pinion. From there, it is sent through the pinion teeth, which are in mesh with the rack teeth. The integral rack piston, which is connected to the rack, changes hydraulic pressure to a linear force (back and forth movement in a straight line). This, in turn, moves the rack in a right or left direction. The force is transmitted by the inner and outer tie rods to the steering knuckles, which, in turn, move the wheels.附錄B懸架與轉(zhuǎn)向系統(tǒng)懸架與轉(zhuǎn)向系統(tǒng)的基本組成與類型 1.懸架系統(tǒng)如果將一輛汽車的車橋直接固定到車架或車身上，道路上的每個(gè)凹凸不平的點(diǎn)都會(huì)將一個(gè)沖擊力傳遞給車輛。乘客會(huì)覺(jué)得不舒適，高速操縱極為困難?，F(xiàn)代汽車乘坐舒適、操控性好就是懸架系統(tǒng)的直接作用結(jié)果。盡管輪胎和車輪必須隨著道路的凹凸不平而上、下跳動(dòng)，但對(duì)車身的影響應(yīng)盡可能小。采用任何一種懸架系統(tǒng)的目的都是允許車身向前移動(dòng)，而將上、下運(yùn)動(dòng)減到最小程度。懸架還應(yīng)允許汽車轉(zhuǎn)彎，但不能有過(guò)大的車身橫搖或輪胎側(cè)滑。2.懸架系統(tǒng)的組成1）車架汽車的車架或車身應(yīng)為懸架系統(tǒng)形成一個(gè)剛性結(jié)構(gòu)基礎(chǔ)，并未該系統(tǒng)提供堅(jiān)固的錨固點(diǎn)。今天常見(jiàn)的車身結(jié)構(gòu)有兩種：車身在車架上的結(jié)構(gòu)（非承載式車身）和整體式結(jié)構(gòu)（承載式車身）。前者采用了單獨(dú)的鋼車架，車身的各個(gè)點(diǎn)通過(guò)連接螺栓固定到車架上；后者的車身各部分均用作結(jié)構(gòu)件。承載式車身結(jié)構(gòu)最常見(jiàn)，而非承載式仍然用在皮卡及大型轎車上。2）彈簧彈簧是懸架系統(tǒng)的最明顯的部分。每輛汽車在其車架或車身與車橋之間都有某種彈簧。今天，使用的彈簧有三種：鋼板彈簧、螺旋彈簧和扭桿彈簧。一輛汽車可以使用兩種不同的彈簧?？諝鈴椈梢欢扔脕?lái)替代其他的彈簧，但現(xiàn)在已經(jīng)過(guò)時(shí)。許多現(xiàn)代汽車都采用空氣懸架，但它們只是用于對(duì)彈簧的補(bǔ)充。3）減振器當(dāng)汽車在一水平路面上向前行駛，并且車輪碾壓到道路上的凸起時(shí)，懸架系統(tǒng)的彈簧就會(huì)快速壓縮（螺旋彈簧）或者扭轉(zhuǎn)（鋼板彈簧和扭桿彈簧）。彈簧試圖返回到原來(lái)的正常安裝位置。因此，彈簧回彈，使車身抬高。由于彈簧已經(jīng)存儲(chǔ)了能量，所以彈簧的回彈會(huì)超過(guò)其正常長(zhǎng)度范圍。汽車的向上跳躍運(yùn)動(dòng)也將有助于彈簧的回彈超過(guò)彈簧的正常長(zhǎng)度范圍。彈簧回彈之后，汽車的重量將使彈簧壓縮。由于汽車向下運(yùn)動(dòng)，下行的車身所積累的能量將推動(dòng)壓縮彈簧，使其高度低于正常的安裝高度。這就導(dǎo)致了彈簧的再次回彈。這個(gè)過(guò)程（叫做彈簧震蕩）逐漸減弱，直至汽車最后靜止為止。彈簧的震蕩會(huì)影響操縱性和乘坐舒適性，因而必須加以控制。4）空氣減振器有些懸架系統(tǒng)采用兩個(gè)可調(diào)的空氣減振器，這兩個(gè)減振器安裝在后懸架上，并且用軟管連接到空氣閥上。空氣減振器采用液壓減振系統(tǒng)，其工作方式與普通減振器相同。此外，空氣減振器內(nèi)還有密閉的空氣室，空氣室的氣壓與來(lái)自高度控制傳感器的壓力相互作用。改變到空氣室的壓力就會(huì)引起減振器長(zhǎng)度即工作范圍的增、減。通過(guò)塑料管將壓縮空氣輸送到空氣減振器。此管將減振器與空氣閥相連。用于升高減振器的壓縮空氣一般取自外部氣源（如維修站壓縮機(jī)），并通過(guò)空氣閥進(jìn)入。為了將不需要的空氣從減振器放掉（降低汽車高度），要壓下空氣閥芯，使空氣放出。5）懸架擺臂所有的汽車都有或擺臂或滑柱，以便保持車輪總成處于正確的位置。擺臂與滑柱可讓車輪上、下移動(dòng)，同時(shí)阻止其他方向的運(yùn)動(dòng)。在汽車加速、制動(dòng)或轉(zhuǎn)彎時(shí)，車輪往往會(huì)產(chǎn)生不希望有的運(yùn)動(dòng)。汽車懸架可以只有擺臂，或者將擺臂與滑柱結(jié)合使用。3.懸架的類型1）前懸架系統(tǒng)幾乎所有的前懸架系統(tǒng)都是獨(dú)立懸架。采用獨(dú)立懸架，每個(gè)前輪都能自由地上、下運(yùn)動(dòng)，對(duì)其他的車輪影響最小。在獨(dú)立懸架系統(tǒng)中，加給車架的扭轉(zhuǎn)作用要遠(yuǎn)遠(yuǎn)小于采用整體式車橋的懸架系統(tǒng)。然而，一些非道路四輪驅(qū)動(dòng)車輛和大型貨車仍然采用整體式車橋前懸架。兩種主要的獨(dú)立前懸架是傳統(tǒng)式獨(dú)立前懸架麥弗遜滑柱式獨(dú)立前懸架。（1）傳統(tǒng)式獨(dú)立前懸架在傳統(tǒng)式獨(dú)立前懸架中，每個(gè)車輪采用一個(gè)或兩個(gè)擺臂。在大多數(shù)系統(tǒng)中，螺旋彈簧安裝在車架與下擺臂之間。而在老式懸架系統(tǒng)中，螺旋彈簧安裝在上擺臂與車身之間。在扭桿彈簧前懸架中，下擺臂上移，從而使扭桿彈簧發(fā)生扭轉(zhuǎn)變形。（2）螺旋彈簧獨(dú)立前懸架一種采用橡膠軸套擺臂支軸的典型的獨(dú)立前懸架。螺旋彈簧的頂部置入一個(gè)杯形件中，并且頂靠在車架上。螺旋彈簧的底部支撐在下擺臂上的彈簧襯墊上。每個(gè)減振器的頂部都固定到車架上，底部都固定到下擺臂上。當(dāng)車輪碰到道路上的凸起部位時(shí)，車輪就會(huì)被向上頂起。這就使擺臂繞支軸向上轉(zhuǎn)動(dòng)，從而使彈簧和減振器被壓縮。橡膠緩沖墊限制擺臂的最大行程，并在到達(dá)極限位置時(shí)，對(duì)擺臂的運(yùn)動(dòng)起到緩沖作用。對(duì)于轉(zhuǎn)向系統(tǒng)而言，前輪轉(zhuǎn)向節(jié)繞球形接頭轉(zhuǎn)動(dòng)。（3）扭桿彈簧獨(dú)立前懸架扭桿彈簧位于汽車前部車架兩側(cè)。下擺臂與扭桿的自由端相連。當(dāng)車輪向上彈起時(shí)，下擺臂向上運(yùn)動(dòng)，從而使長(zhǎng)長(zhǎng)的鋼質(zhì)彈簧桿受到扭轉(zhuǎn)作用。（4）麥弗遜滑柱式獨(dú)立前懸架大多數(shù)現(xiàn)代汽車（特別是前輪驅(qū)動(dòng)汽車）采用了麥弗遜滑柱式獨(dú)立前懸架，麥弗遜滑柱內(nèi)含有一個(gè)螺旋彈簧，該彈簧裝在大打得滑柱-底座組件的頂部上。螺旋彈簧頂部和底部的橡膠襯墊減輕了沖擊。整個(gè)麥弗遜滑柱總成在底座的底部與轉(zhuǎn)向節(jié)相連。麥弗遜滑柱組件的底部通過(guò)球形接頭與單件的擺臂相連。車輪轉(zhuǎn)動(dòng)時(shí)，整個(gè)滑柱總成轉(zhuǎn)動(dòng)。裝在滑柱總成頂部的一個(gè)軸承即推力墊圈使滑柱總成與車身之間可以相對(duì)運(yùn)動(dòng)。球節(jié)使滑柱總成能相對(duì)于擺臂發(fā)生轉(zhuǎn)動(dòng)。滑柱內(nèi)含有減振器，此減振器的工作方式與普通減振器相同。大多數(shù)減振器總成都裝有保護(hù)蓋，以防塵土和水粘到減振器的活塞桿上。麥弗遜滑柱的優(yōu)點(diǎn)是設(shè)計(jì)緊湊，從而對(duì)小汽車車身可以有更大的空間，方便維修。（5）整體式車橋前懸架一般說(shuō)來(lái)，整體式車橋前懸架（即非獨(dú)立懸架）的應(yīng)用僅局限于貨車和非道路車輛。這種懸架系統(tǒng)采用整體式鋼質(zhì)從動(dòng)橋（前軸不隨車輪轉(zhuǎn)動(dòng)），兩側(cè)均采用鋼板彈簧。前軸與輪軸之間的樞軸布置使車輪能在每一端擺動(dòng)。由于兩側(cè)前輪共用一根車軸，因此它們的上、下運(yùn)動(dòng)會(huì)引起自身的垂直傾斜。2）后懸架系統(tǒng)在采用整體時(shí)后橋殼的車輛上，后懸架采用了螺旋彈簧或鋼板彈簧。當(dāng)車輛采用非獨(dú)立后懸架系統(tǒng)時(shí)，可以采用螺旋彈簧、麥弗遜滑柱、單個(gè)橫置鋼板彈簧或者扭桿彈簧。4.轉(zhuǎn)向系統(tǒng)轉(zhuǎn)向系統(tǒng)的設(shè)計(jì)目的是讓駕駛員用最小的力，并且在不過(guò)度轉(zhuǎn)動(dòng)轉(zhuǎn)向盤的情況下，能使前輪向左或向右擺動(dòng)。雖然駕駛員能輕而易舉地使車輪擺動(dòng)，但是不能讓道路的沖擊傳遞給駕駛員。這種無(wú)道路沖擊傳遞的特征被稱為轉(zhuǎn)向系統(tǒng)的不可逆性?；镜霓D(zhuǎn)向系統(tǒng)可以被分為三個(gè)主要的部分：轉(zhuǎn)向節(jié)和轉(zhuǎn)向臂組件；連接轉(zhuǎn)向臂與轉(zhuǎn)向器的轉(zhuǎn)向傳動(dòng)機(jī)構(gòu)；轉(zhuǎn)向盤、轉(zhuǎn)向軸和轉(zhuǎn)向器組件。5.轉(zhuǎn)向器轉(zhuǎn)向器的設(shè)計(jì)目的是放大駕駛員的轉(zhuǎn)向力矩，使前輪擺動(dòng)容易。當(dāng)采用平行四邊形傳動(dòng)桿系時(shí)，駕駛員所加的力矩通過(guò)轉(zhuǎn)向器進(jìn)行放大，然后通過(guò)轉(zhuǎn)向傳動(dòng)機(jī)構(gòu)傳遞給轉(zhuǎn)向節(jié)。對(duì)于齒輪齒條式轉(zhuǎn)向系統(tǒng)，轉(zhuǎn)向軸直接與轉(zhuǎn)向齒輪軸相連。轉(zhuǎn)動(dòng)轉(zhuǎn)向齒輪即可使齒條移動(dòng)，從而帶動(dòng)傳動(dòng)桿件運(yùn)動(dòng)。新型車輛或者采用人力轉(zhuǎn)向器或者采用動(dòng)力轉(zhuǎn)向器。目前使用的轉(zhuǎn)向器有三種：循環(huán)球式轉(zhuǎn)向器、蝸桿滾輪式轉(zhuǎn)向器和齒輪齒條式轉(zhuǎn)向器。6.動(dòng)力轉(zhuǎn)向動(dòng)力轉(zhuǎn)向的設(shè)計(jì)目的是利用液壓力來(lái)加大轉(zhuǎn)向器輸出的正常力矩，從而減小轉(zhuǎn)動(dòng)轉(zhuǎn)向盤所需的作用力。動(dòng)力轉(zhuǎn)向系統(tǒng)應(yīng)能減小轉(zhuǎn)向盤的操縱力，同時(shí)提供足夠的轉(zhuǎn)動(dòng)阻力，以便保持有一定的路感。動(dòng)力轉(zhuǎn)向系統(tǒng)可以與普通的轉(zhuǎn)向系統(tǒng)器或者齒輪齒條轉(zhuǎn)向系統(tǒng)器配合使用。整體式動(dòng)力轉(zhuǎn)向器總成內(nèi)含有控制閥機(jī)構(gòu)、動(dòng)力活塞和齒輪。該轉(zhuǎn)向器輸出的力加給轉(zhuǎn)向搖臂軸。齒輪齒條動(dòng)力轉(zhuǎn)向機(jī)構(gòu)還采用了一個(gè)旋轉(zhuǎn)控制閥，從而可將轉(zhuǎn)向液從動(dòng)力轉(zhuǎn)向泵送給齒條式活塞的一側(cè)。轉(zhuǎn)向盤的運(yùn)動(dòng)被傳遞給轉(zhuǎn)向齒輪。轉(zhuǎn)向齒輪與齒條嚙合。與齒條相連的一體式齒條式活塞將油壓轉(zhuǎn)變成直線作用力，從而將齒條向右或向左推動(dòng)。通過(guò)內(nèi)、外橫拉桿，再將這個(gè)力傳給轉(zhuǎn)向節(jié)，轉(zhuǎn)向節(jié)再帶動(dòng)車輪擺動(dòng)。12