【正文】 距，；y為齒形系數(shù)，可按當(dāng)量齒數(shù)在圖51中查得；為重合度影響系數(shù)，=。一擋齒輪接觸應(yīng)力δ= =五擋齒輪接觸應(yīng)力δ= = 校核都在范圍之內(nèi)，符合要求將作用在變速器第一軸上的載荷作為計(jì)算載荷時(shí)，變速器齒輪的許用接觸應(yīng)力見表51。齒輪在熱處理之后進(jìn)行磨齒，能消除齒輪熱處理的變形；磨齒齒輪精度高于熱處理前剃齒和擠齒齒輪精度，使得傳動(dòng)平穩(wěn)、效率提高；在同樣負(fù)荷的條件下，磨齒的彎曲疲勞壽命比剃齒的要高。變速器的軸應(yīng)有足夠的剛度和強(qiáng)度。前者使齒輪中心距發(fā)生變化，破壞了齒輪的正確嚙合；后者使齒輪相互歪斜，如圖52所示，致使沿齒長(zhǎng)方向的壓力分布不均勻。驗(yàn)算時(shí)將軸看做鉸接支承的梁。第一軸常嚙合齒輪副，因距離支承點(diǎn)近、負(fù)荷又小，通常撓度不大，故可以不必計(jì)算。校核都在范圍內(nèi)，符合要求。軸在轉(zhuǎn)矩和彎矩同時(shí)作用下，其應(yīng)力為 (59) ==式中，；d為軸的直徑，花鍵處取內(nèi)徑；W為抗彎截面系數(shù)。慣性式同步器中有鎖銷式、鎖環(huán)式、滑塊式、多片式、和多錐式幾種。彈性元件是位于滑動(dòng)齒套1圓盤部分徑向孔中的彈簧7。第一階段，同步器離開中間位置，作軸向移動(dòng)并靠在摩擦面上。由于和不等，在上述表面產(chǎn)生摩擦力。第三階段，=0，摩擦力矩消失，而軸向力F仍作用在鎖止元件上，使之解除鎖止?fàn)顟B(tài)，此時(shí)滑動(dòng)齒套和鎖削上的斜面相對(duì)移動(dòng)，從而使滑動(dòng)齒套占據(jù)了換擋位置。 鎖環(huán)式同步器 鎖環(huán)式同步器結(jié)構(gòu)如圖62所示，鎖環(huán)式同步器的結(jié)構(gòu)特點(diǎn)是同步器的摩擦元件位于鎖環(huán)1或4和齒輪5或8凸肩部分的錐形斜面上。在不換擋的中間位置，滑塊凸起部分嵌入嚙合套中部的內(nèi)環(huán)槽中，使同步器用來?yè)Q檔的零件保持在中立位置上。接下來，嚙合套的齒端與鎖環(huán)齒端的鎖止面接觸（圖63a）,使嚙合套的移動(dòng)受阻，同步器處在鎖止?fàn)顟B(tài)，換擋的第一階段工作至此已完成。鎖環(huán)式同步器有工作可靠，零件耐用等優(yōu)點(diǎn)，但因結(jié)構(gòu)布置上的限制，轉(zhuǎn)矩容量不大，而且由于鎖止面在鎖環(huán)的接合齒上，會(huì)因齒端磨損而失效，因而主要用于乘用車和總質(zhì)量不大的貨車變速器中。尺寸a應(yīng)等于1/4接合齒齒距。 圖65 滑塊轉(zhuǎn)動(dòng)距離1—嚙合套 2—鎖環(huán) 3—滑塊 4—鎖環(huán)缺口（4）滑塊端隙 滑塊端隙系指滑塊端面與鎖環(huán)缺口端面之間的間隙，如圖66所示，同時(shí)，嚙合套端面與鎖環(huán)端面的間隙為，要求。預(yù)留后備行程的原因是鎖環(huán)的摩擦面會(huì)因摩擦而磨損，并在接下來的換擋時(shí)，鎖環(huán)要向齒輪方向增加少量移動(dòng)。在空擋位置，～。在設(shè)計(jì)中采用了五檔手動(dòng)變速器，通過較大的變速器傳動(dòng)比變化范圍，可以滿足汽車在不同的工況下的要求，從而達(dá)到其經(jīng)濟(jì)性和動(dòng)力性的要求；變速器掛檔時(shí)用結(jié)合套，雖然增加了成本，但是使汽車變速器操縱舒適度增加，齒輪傳動(dòng)更平穩(wěn)。畢業(yè)設(shè)計(jì)不僅使我學(xué)習(xí)和鞏固了專業(yè)課知識(shí)而且了解了不少相關(guān)專業(yè)的知識(shí)，個(gè)人能力得到很大提高。這種造型方法提供給用戶們的是一種無限的，柔順的，沒有固定控制的曲面，從而取代了那種固定的網(wǎng)狀控制點(diǎn)。我們解決導(dǎo)致強(qiáng)迫變形的最優(yōu)化問題的方法停留在一個(gè)允許不一致的B型活動(dòng)曲線規(guī)曲面細(xì)分曲面描寫上。一般來說，這個(gè)目標(biāo)的追尋已經(jīng)由一種尋找“正確”的曲面描述所構(gòu)成，對(duì)于用戶來說，他們的自由程度是足以控制指揮操作的。舉例來說，盡管幾乎任何用控制嚙合面方法的人都有試著去做一個(gè)概念化的簡(jiǎn)單變化的失敗經(jīng)驗(yàn)，但是最后他們強(qiáng)迫去精確地復(fù)位許多甚至是全部圖形，通過控制點(diǎn)去實(shí)現(xiàn)所希望的外形。附錄 外文文獻(xiàn)Variational Surface modelingWe present a new approach to interactive modeling of freefrom surfaces. Instead of a fixed mesh of control points, the model presented to the user is that of an infinitely malleable surface, with no fixed controls. The user is free to apply control points and curves which are then available as handles for direct manipulation. The plexity of the surface’s shape may be increased by adding more control points and curves, without apparent limit. Within the constraints imposed by the controls, the shape of the surface is fully determined by one or more simple criteria, such as smoothness. Our method for solving the resulting constrained variational optimization problem rests on surface representation scheme allowing nonuniform subdivision of Bspline surfaces. Automatic subdivision is used to ensure that constraints are met, and to enforce error bounds. Efficient numerical solutions are obtained by exploiting linearities in the problem formulation and the representation. The most basic goal for interactive freeform surface design is to make it easy for the user to control the shape of the surface. Traditionally, the pursuit of this goal has taken the form of a search for the “right” surface representation, one whose degrees of freedom suffice as controls for direct manipulation by the user. The dominant approach to surface modeling, using a control mesh to manipulate a Bspline or other tensor product surface, clearly reflects this outlook.The control mesh approach is appealing in large measure because the surface’s response to control point displacements is intuitive: pulling or pushing a control point makes a local bump or dent whose shape is quite easily controlled by fine interactive positioning. Unfortunately, local bumps and dents are not the only features one wants to create. For example, almost anyone who has used a control mesh interface has had the frustrating experience of trying to make a conceptually simple change, but being forced in the end to precisely reposition many—even all—the control points to achieve the desired effect.The work we will describe in this paper represents an effort to escape this kind of inflexibility by severing the tie between the controls and the representation. The model we envision presenting to the user is that of an infinitely malleable piecewise smooth surface, with no fixed controls or structure of its own, and with no prior limit on its plexity or ability to resolve detail. To this surface, the user may freely attach a variety of features, such as points and flexible curves, which then serve as handles for direct interactive manipulation of th