【正文】 上, 這樣有助于懸架繞支點(diǎn)上下運(yùn)動(dòng)。s natural resistance to twisting quickly restores it to its original position, returning the wheel to the road.A torsion bar can store a significantly higher maximum amount of energy than either an equally stressed leaf or coil spring. The torsion offers important weight savings and it is adjustable. In addition, it requires significantly less space than a coil spring.The leaf spring is made of several layers of spring steel stacked one upon the other, Usually, there is one main leaf that uses spring eyes for locating and fastening the spring toe frame or underbody. Several other progressively shorter leaves are placed on the main leaf, and the assembly or leaf pack is held together in the middle by a center bolt and on the ends by rebound clips. Some spring packs use fiber. or plastic pads between leaves to reduce the internal leaf friction. Some vehicles use a single leaf instead of a buildup of multiple leaves. One manufacturer is using a leaf spring manufactured from a nonmetal posite. Leaf springs are usually arched so that the ends are higher than the center when viewed from the side.The leaf spring is usually mounted in three places. A bushing is installed in each of the spring eyes. A bolt through the bushing in the rear spring eye attaches the rear of the spring directly to the vehicle frame. A shackle assembly is attached to the front spring eye and bushing and is then mounted through a shackle bushing to the frame. The shackle assembly allows the leaf spring to pivot up and down. A pair of Ubolts and a tie plate are used to clamp the front or rear axle assembly to the leaf spring.The main advantage of leaf springs is their ability to control vehicle sway and lateral movement. For these reasons, leaf springs are often used on the rear suspension of rear drive vehicles.Many latemodel luxury cars use air springs. The spring is essentially a rubber bag or bladder full of air. A piston is attached to the lower control arm. Movement of the lower control arm causes the piston to move into the air bladder and press the air in the bladder. Air pressure is used to regulate how easy or hard the bladder can be pressed. The air bladder is usually connected to an air pressor, which regulates the action of the air spring based on road conditions.All suspension systems use a shock absorber at each wheel. When the coil, torsion bar, leaf spring, or air spring is deflected, it can oscillate (bounce up and down) uncontrollably, possibly causing the tires to lose contact with the road. This could cause the car to bounce up and down without any control. To prevent this from happening, shock absorbers are used, not to absorb shocks, but to control spring rate and dampen spring shock absorber is a hydraulic device. One end of the shock absorber is attached to a wheel assembly and the other end is attached to the vehicle frame. Shock absorber movement is limited by forcing fluid inside the shock absorber through 附 錄 Ⅱ：中文翻譯汽車懸架系統(tǒng)概述在影響汽車性能的眾多方面中，懸架起著十分重要的作用。感謝所有的同學(xué)，在緊張的學(xué)習(xí)和工作中，與各位同學(xué)的交流，使我得到了許多有益的幫助和啟示。單老師的言傳身教使我受益匪淺。利用MATLAB軟件進(jìn)行計(jì)算，根據(jù)所列微分方程得到車身加速度功率譜、相對(duì)動(dòng)載Fd/G對(duì)q的幅頻特性和懸架動(dòng)撓度f(wàn)d對(duì)q的幅頻特性，利用MATLAB軟件作出曲線圖。主簧主片長(zhǎng)度1530mm，用作圖法確定出其余各片的長(zhǎng)度。在前懸架系統(tǒng)設(shè)計(jì)中，對(duì)鋼板彈簧的參數(shù)進(jìn)行了確定，確定鋼板彈簧的片數(shù)為10片等厚，厚度為8mm，寬75mm，主簧的長(zhǎng)度為1280mm，用作圖法確定出每一片的長(zhǎng)度。根據(jù)車身加速度、懸架彈簧動(dòng)撓度和車輪相對(duì)動(dòng)載的幅頻特性曲線，可以得出本次設(shè)計(jì)的懸架滿足平順性要求，在相應(yīng)的工況下能保證人員的舒適與貨物的完好。方程的解是由振動(dòng)齊次方程的解與非齊次方程特解之和組成。圖41 汽車振動(dòng)系統(tǒng)模型根據(jù)力學(xué)定理，可列出圖41所示系統(tǒng)的振動(dòng)微分方程： （41）式中，為簧載質(zhì)量；為非簧載質(zhì)量； 為左右兩側(cè)懸架的合成剛度；為左右兩側(cè)懸架的合成當(dāng)量阻尼系數(shù)；為左右兩側(cè)懸架的合成輪胎剛度；為簧載質(zhì)量的垂直位移；為簧載質(zhì)量的垂直位移；為路面不平度賦值函數(shù)，即路面不平度對(duì)汽車的實(shí)際激勵(lì)。但是，汽車振動(dòng)是一個(gè)極為復(fù)雜的空間多自由度振動(dòng)系統(tǒng)。三個(gè)界限只是振動(dòng)加速度容許值不同。疲勞－工效降低界限與保持工作效率有關(guān)。我國(guó)參照ISO2631制定了國(guó)家標(biāo)準(zhǔn)《汽車平順性隨機(jī)輸入行駛試驗(yàn)方法》和《客車平順性評(píng)價(jià)指標(biāo)及極限》。如果車身加速度達(dá)到1g，未經(jīng)固定的貨物就有可能離開車廂底板。目前，常用汽車車身振動(dòng)的固有頻率和振動(dòng)加速度評(píng)價(jià)汽車的行駛平順性。在同一路面上以相同車速行駛的不同汽車，由于隔振和減振性能不同，引起的振動(dòng)劇烈程度會(huì)不同。用20鋼或20Cr鋼經(jīng)滲碳處理或用45鋼經(jīng)高頻淬火后，其[]≤7—9 N/mm。許用應(yīng)力[σ]取為350MPa。驗(yàn)算汽車在不平路面上鋼板彈簧的強(qiáng)度。當(dāng)貨車牽引驅(qū)動(dòng)時(shí)，貨車的后鋼板彈簧承受的載荷最大，在它的前半段出現(xiàn)的最大應(yīng)力用下式計(jì)算 =+ 式中，為作用在后輪上的垂直靜載荷，為制動(dòng)時(shí)后軸負(fù)荷轉(zhuǎn)移系數(shù)；轎車：=~；貨車：=~；為道路附著系數(shù)；b為鋼板彈簧片寬；為鋼板彈簧主片厚度。如果相差太多，可重新選擇各片預(yù)應(yīng)力再行核算。4 鋼板彈簧總成在自由狀態(tài)下的弧高及曲率半徑計(jì)算（1）鋼板彈簧總成在自由狀態(tài)下的弧高鋼板彈簧總成在自由狀態(tài)下的弧高，用下式計(jì)算： 式中，為靜撓度；為滿載弧高；為鋼板彈簧總成用U型螺栓夾緊后引起的弧高變化，；S為U型螺栓的中心距。式中，a為經(jīng)驗(yàn)修正系數(shù)，～，E為材料彈性模量； 為主片和第（k+1）片的一般長(zhǎng)度。如果存在與主片等長(zhǎng)的重疊片，就從B點(diǎn)到最后一個(gè)重疊片的上側(cè)邊斷點(diǎn)連一直線，此直線與各片上側(cè)邊的交點(diǎn)即為各片長(zhǎng)度。用變截面少片彈簧時(shí)，片數(shù)在1～4選取。（3）鋼板斷截面形狀的選擇：本設(shè)計(jì)選取矩形截面。==L=1530mm k= S=110mm =550 N/.將上面數(shù)據(jù)代入公式，得：=再計(jì)算主簧平均厚度：= 圓整到15mm有了以后，再選鋼板彈簧的片寬b。 ——為撓度增大系數(shù)。轎車L=(～)軸距；貨車前懸架：L=(～)軸距，后懸架：L=(～)軸距。 2 鋼板彈簧主要參數(shù)的確定 已知滿載靜止時(shí)負(fù)荷=69090N。副簧，主簧的剛度之比為： ， 式中，為副簧的剛度，為主簧的剛度。這兩項(xiàng)要求不能同時(shí)滿足。這樣可以使汽車在不同載荷下，保證鋼板彈簧既有適當(dāng)?shù)膹椥杂钟凶銐虻膹?qiáng)度。后鋼板彈簧由主副兩副鋼板彈簧組成。設(shè)計(jì)減振器時(shí)應(yīng)當(dāng)滿足的基本要求是，在使用期間保證汽車的行駛平順性的性能穩(wěn)定；有足夠的使用壽命。雖然搖臂式減振器能在比較大的工作壓力（1020MPa）條件下工作，但由于它的工作特性受活塞磨損和工作溫度變化的影響大而遭淘汰。汽車車身和車輪振動(dòng)時(shí)，減振器內(nèi)的液體在流經(jīng)阻尼孔時(shí)的摩擦和液體的粘性摩擦形成了減振阻力，將振動(dòng)能量轉(zhuǎn)變?yōu)闊崮?，并散發(fā)到周圍的空氣中去，達(dá)到迅速衰減振動(dòng)的目的。假定同一截面上各片曲率變化值相同，各片所承受的彎矩正比于其慣性矩，同時(shí)該截面上各片的彎矩和等于外力所引起的彎矩。該圖中實(shí)線所示的葉片長(zhǎng)度是經(jīng)過圓整后的尺寸。用作圖法確定各片長(zhǎng)度的方法是基于實(shí)際鋼板彈簧各葉片的展開圖接近梯形梁形狀這一原則來(lái)作圖的,先將各葉片厚度的立方值按同一比例尺沿縱坐標(biāo)繪出，再沿橫坐標(biāo)繪出主片長(zhǎng)度之半(即L／2)和u形螺拴中心距之半(即s／2)，得A、B兩點(diǎn)。貨車前懸架L=（）軸距，后懸架L=（）軸距。fa用來(lái)保證汽車具有給定的高度。鋼板彈簧中部在車軸（橋）上的固定中心至鋼板彈簧兩端卷耳中心之間的距離若相等，則為對(duì)稱式鋼板彈簧；若不相等，則稱為不對(duì)稱式鋼板彈簧。鋼板彈簧在汽車上可以縱置或者橫置。并且各片的彎度是不等的，鋼片越長(zhǎng)彎度越小，這樣裝配后在工作時(shí)可以減小主片所受負(fù)荷，使各片負(fù)荷均勻接近。彈簧兩端的卷耳孔中壓入襯套。而前、后懸架側(cè)傾角剛度的分配會(huì)影響前、后輪的側(cè)偏角大小，從而影響轉(zhuǎn)向特性，設(shè)計(jì)還要考慮懸架側(cè)傾角剛度在前、后軸上的分配。它對(duì)簧上質(zhì)量的側(cè)傾角有影響。（如圖21） 圖21 懸架彈性特性曲線、副簧剛度的分配CA1091載貨汽車后懸架采用主、副簧結(jié)構(gòu)的鋼板彈簧。懸架受到的垂直外力F與由此所引起的車輪中心相對(duì)于車身位移f（即懸架的變形）的關(guān)系曲線，稱為懸架的彈性特性。懸架的彈性特性為線性變化時(shí)，前、后懸架的靜撓度可用下式表示fc1=m1g/c1；fc2=m2g/c2式中，g為重力加速度,g=981cm/s2 。此外，前后懸架的固有頻率接近可以避免產(chǎn)生較大的車身角振動(dòng)，n1n2的汽車高速通過單個(gè)路障時(shí)引起的車身角振動(dòng)小于n1n2的汽車。在滿足零部件質(zhì)量小的同時(shí)，還要保證有足夠的強(qiáng)度和壽命。（3）保證汽車具有良好的操縱穩(wěn)定性。同時(shí)獨(dú)立懸架非簧載質(zhì)量小，可提高汽車車輪的附著性。（5）側(cè)傾中心位置較高，有利于減小轉(zhuǎn)向時(shí)車身的側(cè)傾角。 其主要特點(diǎn)是： （1）組成懸架的構(gòu)件少，結(jié)構(gòu)簡(jiǎn)單，便于維修，經(jīng)濟(jì)性好。非獨(dú)立懸架特點(diǎn)是兩側(cè)車輪安裝于一整體式車橋上，當(dāng)一側(cè)車輪受沖擊力時(shí)會(huì)直接影響到另一側(cè)車輪上，當(dāng)車輪上下跳動(dòng)時(shí)定位參數(shù)變化小。(3) 支承車橋上的車身，并使車身與車輪之間保持適當(dāng)?shù)膸缀侮P(guān)系。范圍內(nèi)，汽車有一定不足轉(zhuǎn)向特性，前懸架側(cè)傾角剛度應(yīng)大于后懸架側(cè)傾角剛度。為充分發(fā)揮彈簧在壓縮行程中作用，常把壓縮行程的阻尼比設(shè)計(jì)得比伸張小。車輪、非獨(dú)立懸架的車軸等屬于簧下質(zhì)量，也叫非