【正文】 式中K為經(jīng)驗(yàn)系數(shù)，K=~，為發(fā)動(dòng)機(jī)最大轉(zhuǎn)矩（）第二軸和中間軸中部直徑 D===36mm 齒輪參數(shù) 模數(shù)的選取遵循的一般原則：為了減少噪聲應(yīng)合理減少模數(shù)，增加尺寬；為使質(zhì)量小，增加數(shù)，同時(shí)減少尺寬；從工藝方面考慮，各擋齒輪應(yīng)選用同一種模數(shù)，而從強(qiáng)度方面考慮，各擋齒數(shù)應(yīng)有不同的模數(shù)。初選齒輪模數(shù) = 齒輪法向模數(shù) = 壓力角壓力角較小時(shí)，重合度大，傳動(dòng)平穩(wěn)，噪聲低；較大時(shí)可提高輪齒的抗彎強(qiáng)度和表面接觸強(qiáng)度。因此，從提高低擋齒輪的抗彎強(qiáng)度出發(fā)，并不希望用過(guò)大的螺旋角，以15～25為宜；而從提高高擋齒輪的接觸強(qiáng)度和增加重合度著眼，應(yīng)選用較大螺旋角。通常根據(jù)齒輪模數(shù)m的大小來(lái)選定齒寬。因?yàn)?=15 輸出軸上一擋齒輪==5715=42 對(duì)中心距進(jìn)行修正因?yàn)橛?jì)算齒數(shù)和后，經(jīng)過(guò)取整數(shù)使中心距有了變化，所以應(yīng)根據(jù)和齒輪變位系數(shù)新計(jì)算中心距，在以修正后的中心距作為各擋齒輪齒數(shù)分配的依據(jù)[13]。因?yàn)辇X輪節(jié)圓直徑d=，z為齒數(shù)，帶入式（51）得 （52）一擋從動(dòng)齒輪 一擋主動(dòng)齒輪 倒擋直齒輪作用彎曲應(yīng)力在400~850N/mm故直齒輪彎曲應(yīng)力均符合要求2） 斜齒輪彎曲應(yīng)力 （53）式中，為圓周力，；為計(jì)算載荷；d為節(jié)圓直徑， ，為法向模數(shù)；z為齒數(shù)；為斜齒輪螺旋角；為應(yīng)力集中系數(shù)，=；b為齒面寬；t為法向齒距，；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)，=。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。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。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。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)。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。由于和不等，在上述表面產(chǎn)生摩擦力。 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。接下來(lái)，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。尺寸a應(yīng)等于1/4接合齒齒距。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(lái)的換擋時(shí)，鎖環(huán)要向齒輪方向增加少量移動(dòng)。在設(shè)計(jì)中采用了五檔手動(dòng)變速器，通過(guò)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)。這種造型方法提供給用戶們的是一種無(wú)限的，柔順的，沒(méi)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)。一般來(lái)說(shuō)，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(lái)說(shuō)，他們的自由程度是足以控制指揮操作的。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