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湘潭大學(xué)
低速載貨汽車變速器的設(shè)計(jì)
摘 要：課題來源于生產(chǎn)實(shí)際，依據(jù)《機(jī)動車安全技術(shù)條件》和《汽車機(jī)械變速器總成技術(shù)條件》，針對低速載貨汽車的運(yùn)行特點(diǎn)而設(shè)計(jì)。參與了汽車的總體設(shè)計(jì)，確定了汽車的質(zhì)量參數(shù)，選擇了合適的發(fā)動機(jī)，并且計(jì)算出汽車的最高速度。
關(guān)于變速器的設(shè)計(jì)，首先選擇標(biāo)準(zhǔn)的齒輪模數(shù)，在總檔位和一檔速比確定后，合理分配變速器各檔位的速比，接著計(jì)算出齒輪參數(shù)和中心距，并對齒輪進(jìn)行強(qiáng)度驗(yàn)算，確定了齒輪的結(jié)構(gòu)與尺寸，繪制出所有齒輪的零件圖。根據(jù)經(jīng)驗(yàn)公式初步計(jì)算出軸的尺寸，然后對每個檔位下軸的剛度和強(qiáng)度進(jìn)行驗(yàn)算，確定出軸的結(jié)構(gòu)和尺寸，繪制出各根軸的零件圖。根據(jù)結(jié)構(gòu)布置和參考同類車型的相應(yīng)軸承后，按國家標(biāo)準(zhǔn)選擇合適的軸承，然后對軸承進(jìn)行使用壽命的驗(yàn)算，最終完成了變速器的零件圖和裝配圖的繪制。
此變速器的齒輪都為標(biāo)準(zhǔn)齒輪，檔位數(shù)和傳動比與發(fā)動機(jī)參數(shù)匹配，保證了汽車具有良好的動力性和經(jīng)濟(jì)性。該變速器具有操縱簡單、方便、傳動效率高、制造容易、成本低廉、維修方便的特點(diǎn)，適合低速載貨汽車的使用。
關(guān)鍵詞：低速載貨汽車；變速器；設(shè)計(jì)
Design The Transmission of Low-speed Truck
Abstract: The topic comes from the production reality, which is based on the safety specifications for power driven vehicles operating on roads and the specifications for the automobile mechanical transmission. It designs the low-speed truck’s movement characteristic. The automobile quality parameters are determined, according to the automobile system design, choosing the appropriate engine, and calculating the maximum speed.
When design the transmission, first, we choose the standard gear modulus and determine all speed’s proportions after we choose the number of the transmission’s gears and the first gear, then calculate the gear’s parameter and the center distance, and the gear needs the intensity checking calculation. We determine gear’s structure, then complete drawing of the gears’ component. According to the empirical formula, we preliminary carry on the checking calculation to each gear’s rigidity and the intensity to determine the axis’ structure and size, and thus draw up various axis’ component drawing. After arranged structure and compared with the similar type of vehicle’s bearing, according to the national standard, we select the appropriate bearings, and then calculate the service life of the bearings. Finally drawing of the component and the assembly of the transmission are completed.
Because the transmission gear is the standard gear and the number of gears and speed’s proportions match to the engine conditions, which ensure the necessary power and economy. This transmission has many merits of simple operation, efficient, easy manufacturing, low cost, and convenient.
Key words: Low-speed Truck；Transmission；Design
載重汽車變速箱
變速箱主要指的是汽車的變速箱，它分為手動、自動兩種，手動變速箱主要由齒輪和軸組成，通過不同的齒輪組合產(chǎn)生變速變矩；而自動變速箱AT是由液力變扭器、行星齒輪和液壓操縱系統(tǒng)組成，通過液力傳遞和齒輪組合的方式來達(dá)到變速變矩。功能為：一、改變傳動比；二、在發(fā)動機(jī)旋轉(zhuǎn)方向不變情況下，使汽車能倒退行駛；三、利用空擋，中斷動力傳遞，以發(fā)動機(jī)能夠起動、怠速，并便于變速器換檔或進(jìn)行動力輸出。
手動變速箱主要由齒輪和軸組成，通過不同的齒輪組合產(chǎn)生變速變矩；而自動變速箱AT是由液力變扭器、行星齒輪和液壓操縱系統(tǒng)組成，通過液力傳遞和齒輪組合的方式來達(dá)到變速變矩。
其中液力變扭器是AT最具特點(diǎn)的部件，它由泵輪、渦輪和導(dǎo)輪等構(gòu)件組成，直接輸入發(fā)動機(jī)動力傳遞扭矩和離合作用。泵輪和渦輪是一對工作組合，它們就好似相對放置的兩臺風(fēng)扇，一臺主動風(fēng)扇吹出的風(fēng)力會帶動另一臺被動風(fēng)扇的葉片旋轉(zhuǎn)，流動的空氣——風(fēng)力成了動能傳遞的媒介。如果用液體代替空氣成為傳遞動能的媒介，泵輪就會通過液體帶動渦輪旋轉(zhuǎn)，再在泵輪和渦輪之間加上導(dǎo)輪以提高液體的傳遞效率。由于液力變矩器自動變速變矩范圍不夠大且效率偏
手動變速器（MT）
手動變速器，也稱手動擋，即用手撥動變速桿才能改變變速器內(nèi)的齒輪嚙合位置，改變傳動比，從而達(dá)到變速的目的。踩下離合時(shí)，方可撥得動變速桿。如果駕駛者技術(shù)好，裝手動變速器的汽車在加速、超車時(shí)比自動變速車快，也省油。
自動變速器（AT）
自動變速器，利用行星齒輪機(jī)構(gòu)進(jìn)行變速，它能根據(jù)油門踏板程度和車速變化，自動地進(jìn)行變速。而駕駛者只需操縱加速踏板控制車速即可。
一般來講，汽車上常用的自動變速器有以下幾種類型：液力自動變速器、液壓傳動自動變速器、 電力傳動自動變速器、有級式機(jī)械自動變速器和無級式機(jī)械自動變速器等。其中，最常見的是液力自動變速器。液力自動變速器主要是由液壓控制的齒輪變速系統(tǒng)構(gòu)成，主要包含自動離合器和自動變速器兩大部分。它能夠根據(jù)油門的開度和車速的變化，自動地進(jìn)行換擋。
無級變速器（CVT）
無級變速器是由兩組變速輪盤和一條傳動帶組成的。
因此，其比傳統(tǒng)自動變速器結(jié)構(gòu)簡單，體積更小。另外，它可以自由改變傳動比，從而實(shí)現(xiàn)全程無級變速，使汽車的車速變化平穩(wěn)，沒有傳統(tǒng)變速器換擋時(shí)那種“頓”的感覺。
無級變速器屬于自動變速器的一種，但它能克服普通自動變速器“突然換擋”、油門反應(yīng)慢、油耗高等缺點(diǎn)。
變速器是法國雷諾(Renault)發(fā)明的
普通自動變速箱
優(yōu)點(diǎn)：使駕駛輕松愜意
缺點(diǎn)：不夠智能，相對費(fèi)油，不利于改裝
普通自動變速箱是自動擋車普遍使用的變速箱形式，它的簡稱AT（全稱是Auto Transmission）幾乎成為自動擋的代名詞。
和手動擋相比，普通自動變速箱在結(jié)構(gòu)和使用上有很大不同。手動波主要通過調(diào)節(jié)不同齒輪組合更換擋位，而普通自動變速箱是通過液力傳遞和齒輪組合的方式來達(dá)到變速的目的。其中液力變扭器是普通自動變速箱最具特點(diǎn)的部件，它由泵輪、渦輪和導(dǎo)輪等構(gòu)件組成，泵輪和渦輪是一對工作組合，泵輪通過液體帶動渦輪旋轉(zhuǎn)，而泵輪和渦輪之間的導(dǎo)輪通過反作用力使泵輪和渦輪之間實(shí)現(xiàn)轉(zhuǎn)速差并實(shí)現(xiàn)變速變矩功能，對駕駛者來說，您只需要以不同力度踩住踏板，變速箱就可以自動進(jìn)行擋位升降。由于液力變矩器自動變速變矩范圍不夠大，因此在渦輪后面再串聯(lián)幾排行星齒輪提高效率，液壓操縱系統(tǒng)會隨發(fā)動機(jī)工作變化自行操縱行星齒輪，從而實(shí)現(xiàn)自動變速變矩。為了滿足行駛過程中的多種需要（如泊車、倒車）等，普通自動變速箱還設(shè)有一些手動撥桿位置，像P擋（停泊）、R擋（后擋）、N擋（空檔）、D擋（前進(jìn)）等，一些在前進(jìn)檔中還設(shè)有“2”和“1”等附加擋位，用以起步或上斜坡之用。
從普通自動變速箱的發(fā)展來看，具有四前速的變速箱（就是前進(jìn)中可以在四個擋里進(jìn)行切換）已經(jīng)是比較基礎(chǔ)的配置，在中高級車市場中，五前速自動變速箱已經(jīng)成為主流，而高檔車?yán)锪八僮詣幼兯傧?、甚至七前速自動變速箱都已?jīng)屢見不鮮，可以說自動變速箱有幾個擋就標(biāo)志著車的“身價(jià)”，當(dāng)然，從性能上說自動變速箱的擋位越多，車在行駛過程中也就越平順，加速性也越好，而且更加省油。
除了提供輕松愜意的駕駛感受，普通自動變速箱也有無法克服的缺陷。普通自動變速箱的動力響應(yīng)不夠直接，這使它在“駕駛樂趣”方面稍顯不足。此外，由于采用液力傳動，這使普通自動擋變速箱傳遞的動力有所損失，也就更費(fèi)油一些（比同型號手動擋車油耗要高10%左右）。在山道行駛中，普通自動變速箱對于高高低低的起伏路面顯得不夠“智能”，容易在不同擋位里無謂切換，如果您的愛車沒有爬坡?lián)醯脑捑椭荒芤换I莫展了。對那些改裝玩家而言，裝備普通自動變速箱的車需要慎重選擇，因?yàn)檫@類變速箱可以承受的扭矩范圍比較有限，而變速箱油溫過高的話又會直接影響車子的動力表現(xiàn)。
手自一體
優(yōu)點(diǎn)：提供更好的駕駛樂趣
缺點(diǎn)：價(jià)格太高
顧名思義，“手自一體”變速箱就是把手動換擋和自動換擋兩種模式結(jié)合在一起的變速形式，在這類變速箱上，都有顯著的+/－標(biāo)志，你可以切入這個位置手動切換擋位。
對普通變速箱而言，駕駛樂趣不足一直是它的弊病，您在入彎前踩剎車減速，普通自動變速箱只會跳到空擋或維持原擋位不動，它不會隨著速度下降而降低一擋；到了出彎當(dāng)你加油時(shí)變速箱又會來一個kickdown（向下跳一擋），然后才獲得足夠力量加速。這不但比手動變速多了時(shí)間，而且在彎中擋位跳動也會破壞車身平衡。手自一體變速箱最大用處就是提高擋位的“隨心所欲”程度，換句話說，就是“如果它不夠聰明，至少我可以自己來”。有了手動選擋模式，您在彎前就可以手動降至適當(dāng)?shù)膿跷?，在彎中又可以保持需要的轉(zhuǎn)速，出彎時(shí)便有足夠的動力。功能上看手自一體變速箱和手動變速箱沒有分別，但一臺好的手自一體變速箱其手動模式有足夠快的加、減擋反應(yīng)，否則就顯得有些華而不實(shí)。
結(jié)構(gòu)上看，手自一體變速箱還是一臺自動變速箱，因此配置普通自動變速箱的車型油耗相對較高、不利改裝等缺陷在它身上依然可以看到。此外，由于這類變速箱仍需進(jìn)口，成本就比一般變速箱要高不少，因此整車價(jià)格也就不便宜。但對一個家庭來說，如果男主人傾向駕駛樂趣，女主人偏愛輕松愜意的駕駛感受，配置手自一體變速箱的車型還是不錯的選擇。
CVT無級變速箱
優(yōu)點(diǎn)：省油，有很好的平順感，動力響應(yīng)直接
缺點(diǎn)：應(yīng)用車型少，配件價(jià)格高
CVT無級變速箱的全稱是Continuosuly Variable Transmission，功能上看它也是自動變速箱的一種，但和其他自動變速箱采用液力藕合的傳動方式不同，CVT無級變速箱采用傳動鋼帶和工作直徑可變的主、從動輪相配合來傳遞動力，從而實(shí)現(xiàn)傳動比的連續(xù)改變。坐在裝有CVT變速箱的車?yán)锬憬^感受不到換擋沖擊（因?yàn)樗揪蜎]有擋），這就使車速變化更為平穩(wěn)，不會出現(xiàn)傳統(tǒng)自動變速器換擋時(shí)那種頓挫感。此外，CVT還有重量輕、體積小、零件少的特點(diǎn)，加上這種傳動形式功率損耗小，這樣就為車帶來省油的好處。經(jīng)驗(yàn)證明，配置CVT無級變速箱的車型甚至比同排量手動擋車型油耗還低。
隨著CVT技術(shù)越來越成熟，及國內(nèi)汽車產(chǎn)業(yè)的快速發(fā)展，國內(nèi)市場上裝備CVT汽車越來越多，奧迪、豐田、本田、菲亞特等各大公司都先后推出自己的CVT汽車產(chǎn)品。
CVT（Continuously Variable Transmission），直接翻譯就是連續(xù)可變傳動，也就是我們常說的無級變速箱，顧名思義就是沒有明確具體的檔位，操作上類似自動變速箱，但是速比的變化卻不同于自動變速箱的跳擋過程，而是連續(xù)的，因此動力傳輸持續(xù)而順暢。
CVT傳動系統(tǒng)里，傳統(tǒng)的齒輪被一對滑輪和一只鋼制皮帶所取代，每個滑輪其實(shí)是由兩個椎形盤組成的V形結(jié)構(gòu)，引擎軸連接小滑輪，透過鋼制皮帶帶動大滑輪。玄機(jī)就出在這特殊的滑輪上：CVT的傳動滑輪構(gòu)造比較奇怪，分成活動的左右兩半，可以相對接近或分離。錐型盤可在液壓的推力作用下收緊或張開，擠壓鋼片鏈條以此來調(diào)節(jié)V型槽的寬度。當(dāng)錐型盤向內(nèi)側(cè)移動收緊時(shí)，鋼片鏈條在錐盤的擠壓下向圓心以外的方向（離心方向）運(yùn)動，相反會向圓心以內(nèi)運(yùn)動。這樣，鋼片鏈條帶動的圓盤直徑增大，傳動比也就發(fā)生了變化。CVT變速箱有哪些優(yōu)點(diǎn)？1、由于沒有了一般自動擋變速箱的傳動齒輪，也就沒有了自動擋變速箱的換擋過程，由此帶來的換檔頓挫感也隨之消失，因此CVT變速箱的動力輸出是線性的，在實(shí)際駕駛中非常平順。2、CVT的傳動系統(tǒng)理論上擋位可以無限多，擋位設(shè)定更為自由，傳統(tǒng)傳動系統(tǒng)中的齒輪比、速比以及性能、耗油、廢氣排放的平衡，都更容易達(dá)到。3、CVT傳動的機(jī)械效率、省油性大大優(yōu)于普通的自動擋變速箱，僅次于手動擋變速箱，燃油經(jīng)濟(jì)性要比好很多。奧迪A6L的CVT變速箱解剖圖奧迪A6L的CVT變速箱鋼帶既然有這么多優(yōu)點(diǎn)，為什么不讓所有的汽車都采用CVT變速箱呢？有兩方面因素：1、相比傳統(tǒng)自動擋變速箱而言，它的成本要略高；而且操作不當(dāng)?shù)脑?，出問題的概率更高。2、CVT變速箱本身還有它的缺點(diǎn)，就是傳動的鋼制皮帶能夠承受的力量有限，一般而言超過2.8L排量或者280N·M以上的動力是它的上限，不過我們也看到有越來越多的車型，諸如奧迪或者日產(chǎn)，都已經(jīng)打破了這個上限，相信鋼帶的問題會逐步得到解決。
Automobile transmission
Transmission mainly refers to the automobile gearbox, it divided into two kinds of manual, automatic, manual transmission is mainly composed of gear and shaft, by different gear combinations to produce variable torque; And automatic transmission AT consists of hydraulic torque converter, planet gear and the hydraulic control system, hydraulic transmission and gear combination ways to achieve variable speed torque. Function as follows: first, change the transmission ratio; Second, under the condition of constant motor rotation direction, make the car can drive back; Three, use neutral, interrupt power transmission to the engine starting, idling, and facilitate the transmission shift or power output.
Manual transmission is mainly composed of gear and shaft, by different gear combinations to produce variable torque; And automatic transmission AT consists of hydraulic torque converter, planet gear and the hydraulic control system, hydraulic transmission and gear combination ways to achieve variable speed torque.
Of hydraulic torque converter is parts AT the most characteristics, it is composed of pump wheel, wheel and turbine components, direct input engine torque and power transfer to the clutch. Pump wheel and turbine is a pair of work, as if they are relatively placed two fan, a fan blowing the wind will drive the other passive fan blades spin, the flow of air, wind power into the kinetic energy transfer medium. If replace air as medium of transfer of kinetic energy, by liquid pump wheel will be through the liquid turns the turbine, then between turbine and pump wheel and wheel in order to improve the transfer efficiency of the liquid. Because of the hydraulic torque converter efficiency of automatic transmission torque range is not big enough and partial
Manual transmission (MT)
Manual transmission, also called the manual gear box hand toggle lever to change gear within the transmission meshing position, change the transmission ratio, so as to achieve the purpose of speed change. On the clutch, can dial need to move the shift lever. If the driver technology is good, with a manual transmission vehicle during acceleration, overtaking is faster than a car automatic transmission, and fuel efficiency.
Automatic transmission (AT)
Automatic transmission, the use of planetary gear mechanism for variable speed, it can according to the degree of the accelerator pedal and the speed change, speed automatically. While the driver need to manipulate the accelerator pedal to control the speed.
Commonly used in general, the car automatic transmission has the following several types: hydraulic automatic transmission, hydraulic transmission, automatic transmission, power transmission, automatic transmission, the step type machinery automatic transmission and stepless automatic transmission, etc. Among them, the most common is hydraulic automatic transmission. Hydraulic automatic transmission is mainly composed of the hydraulic control system of gear, and mainly consists of automatic clutch and automatic transmission of two parts. It can according to the throttle opening and the speed of change, to shift automatically.
Stepless transmissions (CVT)
Stepless transmission is composed of two sets of variable speed wheel and a transmission belt.
Its than a conventional automatic transmission, therefore, simple structure, smaller volume. In addition, it is free to change the gear ratio, so as to realize infinitely variable speed all the way, the car's speed changes smoothly, no traditional transmission shift ", "sort of feeling.
Stepless transmission belongs to a kind of automatic transmission, it can overcome the common automatic transmission "suddenly shift", throttle response is slow and high fuel consumption shortcomings.
The transmission was invented by the French Renault (Renault)
Common automatic transmission
Advantage: make the ease of driving
Disadvantages: smart enough, relative to oil, which is unfavorable for modification
Common automatic Transmission is widely used for automatic stop block Transmission form, it is short for ats (full name is the Auto Transmission) almost become the pronoun of automatic.
Compared with manual, common automatic transmission are quite different in the structure and application. Manual wave mainly by adjusting the different gear combination of change gear, while the common automatic transmission is by means of hydraulic transmission and gear combination to achieve the purpose of speed change. With hydraulic torque converter is the most common automatic transmission characteristics of components, it is composed of pump wheel, wheel and turbine components, pump wheel and turbine are a work portfolio, pump wheel through the liquid turns the turbine, and between the turbine and pump wheel roller by reaction between the pump wheel and turbine speed difference and realize variable speed torque function, for the driver, you only need to with different strength on the pedals, transmission can automatically block a lift. Due to hydraulic torque converter automatic transmission torque range is not big enough, so rows behind the turbine again series planetary gear efficiency, hydraulic control system will change with the engine work to manipulation of the planetary gear, so as to realize automatic transmission torque. In the process of driving in order to meet the multiple needs (such as parking and reversing), common automatic transmission also has some manually dial the stem position, like a P block (berth), R (back), N (gap), D block (forward), etc., some in the forward also has additional tests such as "2" and "1", to start or on slopes.
From the perspective of the development of common automatic transmission, it has four QianSu gearbox (that is, in advance can switch) in the four block based configuration are compared, in the senior car market, five QianSu automatic transmission has become the mainstream, and high-grade car six QianSu seven QianSu automatic transmission, and even have become common automatic transmission, automatic transmission, so to speak a few marks the "worth" of a car, of course, on the performance of automatic transmission gears, the car will be smooth in the process of driving, the acceleration is the better, and more fuel efficient.
In addition to the ease of driving experience, common automatic transmission have insurmountable shortcomings. Common automatic transmission of dynamic response is not directly, which makes it slightly shortage in terms of "fun to drive". In addition, due to adopt hydraulic transmission, which makes ordinary automatic gearbox transmission power loss, also some more oil than is the manual (buffer consumption is higher than 10%). Driving in the road, low common automatic transmission for the ups and downs road is "smart" enough, easy to switch in different tests are meaningless, if your car without climbing gear can only be helpless. For those modification player equipment common automatic transmission car need to choose carefully, because this kind of gearbox can withstand the torque range is more limited, and the transmission oil temperature is too high and will directly affect the dynamic performance of the car.
Since the one hand
Advantages: provide better fun to drive
Weakness: the price is too high
As the name implies, "hand from a body gear box is the manual shift and automatic shift change form two patterns together, in this kind of gearbox, have significant + / - sign, you can cut the position switch gears manually.
For ordinary gearbox, lack of driving pleasure has always been its ills, the brakes to slow down before you into the corner, common automatic transmission will only jump to neutral or keep the original block, it will not be reduced with the decline in the block; At the gearbox will come again when you come on a kickdown (jump down a block), and then get enough power to accelerate. This not only more than the manual transmission time, and in turn gear beating also can destroy the body balance. Hand since the gearbox biggest use is to raise the tests of "free", in other words, is "if it's not smart enough, at least I can help myself". With manually selected block mode, you can manually before bending down to the appropriate gear, in turn, can keep the need to speed, the exit when it have enough power. Function on hand no distinction from the gearbox and manual transmission, but a good hand since the gearbox of the manual mode is fast enough plus and minus reaction, otherwise it appears some eye candy.
Hand structure point of view, the gearbox is an automatic transmission, so the allocation of common automatic transmission vehicle fuel consumption is relatively high, defects such as unfavorable modification can still be seen on it. In addition, due to still need to import this kind of gearbox, the cost is higher than the average transmission, so the vehicle price is not cheap. But for a family, if the host fun to drive, the hostess prefer the ease of driving experience, configuration hand since the gearbox model is a good choice.
The CVT transmission gearbox
Advantages: fuel efficient, have very good feeling, smooth dynamic response directly
Disadvantages: less application models, accessories price is high
CVT stepless gearbox Continuosuly is the full name of the Variable Transmission, the functional point of view it is also a kind of automatic Transmission, but and other automatic Transmission with hydraulic coupling Transmission way is different, the CVT Transmission stepless Transmission adopts the steel belt Transmission and working diameter Variable of the main, driven wheel combination to transmit power, so as to realize the continuous change of Transmission ratio. In the car with CVT transmission shift impact absolutely impossible to find (because it doesn't have a block), which makes the speed change more smoothly, there will not be a conventional automatic transmission shift when the sense of frustration. In addition, the CVT transmission and the characteristics of light weight, small size, less parts, and this form of transmission power loss is small, thus for the benefits of fuel-efficient cars. Experience has shown that allocation of CVT stepless transmission models even fuel consumption is lower than with manual displacement model.
As CVT technology more and more mature, and the rapid development of domestic automobile industry, the domestic market equipped with CVT car more and more, audi, Toyota, Honda, fiat, etc. The company has successively launched their own CVT car products.
CVT (Continuously Variable Transmission), direct translation is a continuous Variable Transmission, namely we often say the stepless Transmission, just as its name implies is that there is no specific gear, operating on automatic Transmission, but it is different from automatic Transmission speed ratio change jump process, but a continuous, so that power Transmission continuous and smooth.
CVT transmission system, the traditional gear replaced by a pair of pulleys and a steel belt, and each block is composed of two vertebral shape plate v-shaped structure, engine small pulley shaft connections, through the steel belt drive pulley. Loving you out on this special pulley: CVT transmission pulley structure more strange, divided into activities around two and a half, can be relatively close to or separate. Conical disc can be tightened or under the action of a hydraulic thrust open, extrusion sheet steel chain in order to adjust the width of v-groove. When conical plate to the inside of the move to tighten, sheet steel chain under the extrusion of zahn outside to the center of the circle (centrifugal direction) in the direction of the movement, in contrast to the center of a circle within the movement. So, driven chain wheel diameter of the steel increases, the velocity ratio is changed. What are the advantages of CVT transmission? 1, since there is no general automatic gearbox transmission gear, there would be no automatic transmission shift process, the resulting shift frustration feeling has disappeared, so the CVT transmission power output is linear, in actual driving is very smooth. 2 gears, the CVT transmission system theory can be an infinite number, block a set more freedom, the traditional transmission system gear ratio, speed ratio as well as the performance, fuel consumption and exhaust emissions of balance, are easier to achieve. 3, the mechanical efficiency of CVT transmission, oil province is greatly superior to ordinary automatic gearbox, second only to manual transmission, fuel economy than a lot better. Audi A6L CVT transmissions of the anatomy of the audi A6L of CVT transmission steel belt since there are so many advantages, why not let all cars use the CVT transmission? There are two factors: 1, compared with the traditional automatic transmission, its cost is slightly high; And improper operation, a problem of probability is higher. 2, CVT transmission itself, and its shortcomings, is the driving force of steel belt can withstand is limited, generally more than 2.8 L displacement or 280 n · M it is the power of the upper limit of, but we also see more and more models, such as audi or nissan, has broken this limit, believe that steel belt problem will be solved step by step.