外文翻譯--6檔自動變速器和cvt 對燃油經(jīng)濟性的貢獻

1、<p>　　Six-Speed Automatic Transmission sand CVT′s to Support Fuel Economy</p><p>　　[Abstract]The improvement in fuel economy and in CO2 emission levels has a high priority in the development work of new

2、 passenger cars and new models. New ly developed 6-speed automatic transmissions and continuously variable transmissions (CVT) w ill be available in vehicles in the near future. These transmissions will fulfill the requi

3、rements to reduce fuel consumption and emissions and will increase driving comfort at the same time. A comparison with the state of the art solutions, i. e. 5-sp</p><p>　　1　Introduction</p><p>　

4、　Currently in passenger car development, a reduction in fuel consumption is one of the key criteria that a new vehicle or a new model is measured for. In Europe, the motivating force behind this is the 1991 self2adopted

5、m ission of German automotive manufacturers to reduce fuel consumption by 25 % by the year 2005 and the proposal sent by the A association of European Automotive Industry (ACEA) to the European Comm. ission in 1995 calli

6、ng for a reduction of fleet consumption for the vehicles lice</p><p>　　W hen calling for a reduction in fuel consumption, other criteria demanded of the driveline must be taken into consideration. In particu

7、lar, performance should be mentioned here. Fuel reduction and performance optima isation represent conflicting objectives for driveline developments and are typical of many technical tasks. An appropriate compromise must

8、 be found for the individual applications.</p><p>　　In addition to m minimum fuel consumption and good performance values, drive comfort also plays an increasingly important role as an evaluation criterion f

9、or assessing passenger cars. W within Europe, this is also resulting in an increasing proportion of automatic transm issions (see Figure 1).Due to the setting of elements fitted as standard in automatic transm issions, t

10、he hydrodynamic torque converter, oil pump, hydraulic unit and drag losses in shift elements result in automatic transm issio</p><p>　　Fig. 1　Development of the automatic transmissions penetration in passeng

11、er cars in Western Europe</p><p>　　Since different transm ission system s are appropriate for different applications in passenger cars , a general comparison of how the transm ission impacts fuel consumption

12、 is of limited use. This paper w ill not provide details of how all the named system s impact fuel consumption, but itw ill consider the potential for improving fuel consumption for selected transm ission systems. The pa

13、per w ill focus on systems, which are being launched as volume production models. A few comments regarding t</p><p>　　2　Fuel savings and performance</p><p>　　The European ECE driving cycle consi

14、sts of one third urban travel and two thirds constant travel at 90 and 120 km/h respectively and has been used as a basis for comparing fuel consumption for many years in Europe. Currently the New European Driving Cycle

15、(NEDC = NEFZ = “Neue Europaische Fahrzyklus”) or MVEG (Motor Vehicle Emissions Group) for vehiclesof up to 2. 5 tons defines the basis for evaluating fuel consumption and exhaust emissions (see Figure 2). This overall dr

16、iving cycle ill characte</p><p>　　Take off acceleration (distance reached after 4 seconds), full load acceleration (time to reach 100 km/h or 60mph from 0 km/h) and elasticity (time taken to increase from 80

17、 to 120 km/h), which represent important parameters in the customer’s evaluation of a vehicle today have been established as the assessment criteria for performance. A ssessmentsmade in this paperw ill focus on full load

18、 acceleration, which w ill be specified as time in seconds.</p><p>　　Fig. 2　European driving cycle (NEDC)</p><p>　　The consumption2acceleration2diagram ( see Figure 6) is a tool to describe cons

19、umption and performance in one diagram. Based on full throttle acceleration, this depicts the fuel consumption of a vehicle with one particular engine and different transmissions. Another parameter is the axle ratio whic

20、h influences fuel consumption and acceleration. The consumption-accelerationdiagram will vary if, for example, mpg (m iles per gallon) is applied to the consumption axis instead of l/100 km (litresper </p><p&g

21、t;　　The consumption and acceleration values shown in this paper aremainly based on simulation calculations. In the simulationmodel, the lossesof different transmission system s as measured values from transmission tests

22、are taken into consideration so the influenceof the transmission is depicted realistically. In order to issue a statement regarding the accuracy of the simulation results, some of the calculated results were compared w i

23、t the measured values. This showed the absolute values are not a</p><p>　　3　Transmission concepts</p><p>　　In the past, 4- and 5-speed manual transmissions (M T) were the main transmissions foun

24、d on the European market. Thanks to their mechanical structure, they are efficient but as a result of increased traffic and greater emphasis on comfort, they no longer satisfy the requirements of many customers. Therefor

25、e 4-and 5-speed automatic transmissions (AT ) are also used. Currently these offer a very high level of drive comfort, but have the disadvantage of higher power losses and generally result in h</p><p>　　Manu

26、al transmissions are experiencing a trend towards 6 gears, shift and clutch automation. This results in automated manual transmissions (AMT). U sing hydraulically or electro-mechanically actuated AMT system s, which are

27、based on the mechanics of manual transmissions, shifts can be implemented using the automatic control of a shift program.</p><p>　　A power shift process characterizes shifts in automatic transmission system

28、s with no interruption to traction. In 2001 the first 6-speed automatic transmission was introduced in the market. In addition to 62speed automatic transmissions, there are also continuously variable transmissions (CVT)

29、on the market with push belts and chains serving as the torque transmitting element and continuously variable to roidal drives which are developed as roller-type transmissions. Dual clutch transmissions b</p><

30、p>　　As previously mentioned, the following comparison of fuel consumption and driving performance is limited to transmission systems which are being launched as volume production models or will be available on the mar

31、ket in the near future. For standard driveline configurations with the engine installed longitudinally at the front and with rear-wheel drive (RWD), 6 speed manual transmissions will be increasingly u2sed for the upper t

32、orque range. Section 4 briefly deals with how this impacts fuel con</p><p>　　Fig. 3　ZF transmission systems 5HP24 and 6HP26</p><p>　　Fig. 4　Comparison of a 52speed FQ2transmission and ZF2CFT23 s

33、ystem</p><p>　　4　Fuel saving using 6-speed manual transmissions</p><p>　　An evaluation of published fuel consumption and acceleration values for a 6-speed manual transmission launched into the m

34、arket in the last few years in comparison with the previous 5-speed product shows that no reduction in fuel consumption is achieved by the additional gear in the test cycle. The test conducted with the 6-speed transmissi

35、on resulted in 2 to 5% higher fuel consumption compared to the 52speedmodel and the acceleration values are around 5 to 2% worse. There are several reasons for</p><p>　　●Higher transmission losses as a resul

36、t of additional gears and synchronizers</p><p>　　●Close ratio steps of the lower gears</p><p>　　● No significant influence of the sixth gear in the test cycle</p><p>　　●As a result

37、of the design of the transmission and axle ratio, increased engine speed results from the shift points specified in the test cycle. The new 6-speedmanual transmission shows a sixth gear does not necessarily result in imp

38、roved fuel consumption, emission and acceleration values.</p><p>　　5　Fuel saving using 6-speed automatic transmissions</p><p>　　The 52speed automatic transmission, ZF5HP24, is designed for engin

39、e torques of up to 420 Nm and is therefore most suitable for use with 8-cylinder internal combustion engines. The total gear ratio is itotal= 4. 44. For a comparable application with a torque of 440Nm, the 62speed automa

40、tic transmission ZF 6HP26 has a total ratio of itotal=6. 04. The increase in total ratio (of approx. 36%) assists in significantly reducing fuel consumption. The Lepelletier planetary gear system displays good gear</p

41、><p>　　●Development of a new gear rotor pump with educed displacement volumetric flow, reduced leakage and reduced mechanical power losses</p><p>　　●Optimisation of the oil supply with reduced leak

42、age losses, in particular in the hydraulic control system</p><p>　　●Optimisation of oil guidance with in the transmission to reduce track losses</p><p>　　●Efficiency-optimised oil which lowers t

43、ransmission track losses most especially at low operating temperatures</p><p>　　●Increase in performance in the torque converter lock2up clutch. This enables the torque converter lock2up clutch to be activat

44、ed at low road speeds</p><p>　　●Modified dimensions of one shift element for stand-by-control (neutral idle)</p><p>　　●Optimisation of the adaptive shift program to spontaneously provide the per

45、formance expected by means of addition driver type detection and driver characteristics detection functions despite the economic design.</p><p>　　The result can be seen in Figure 5. Simulating the fuel consu

46、mption with a vehicle from the upper mid-range class with a 4.4 litre 8-cylinder internal combustion engine and the axle ratios shown in the diagram results in an almost 2% consumption thanks to the higher total gear rat

47、io. The aforementioned optimisation measures undertaken on the transmission and the new oil add to a reduction in consumption of around the same value. When using stand-by-control , around another two percent can be rea&

48、lt;/p><p>　　If we consider the performance values for this configuration, we find an improvement of 0. 3 seconds for acceleration from 0 to 100 km/h (Figure 6). This corresponds to a gain of around 4%. The gain

49、 in distance covered after 4 seconds is 3.1 me-tres or 9%, which at any rate corresponds to around half a vehicle length.</p><p>　　These results can also be depicted in a consumption-acceleration-diagram in

50、which different axle ratios have been simulated for the 6HP26 (see Figure 6). The best solution based on European figures can be found in the bottom left of this diagram. This diagram show s the rear axle ratio selected

51、(iRAR = 3. 15) contributes to the minimum achievable fuel consumption and at the same time increased acceleration ability of around 4%. The acceleration ability could be increased further by using a great</p><

52、p>　　Fig. 5　Consumption comparison between 5HP24 and 6HP26</p><p>　　Fig. 6　Consumption-acceleration2diagram for 5HP24 and 6HP26</p><p>　　6　Fuel consumption using CVT</p><p>　　Toda

53、y most small cars and vehicles of the lower mid-range and mid-range class have front-wheel drive with engine and transmission fitted transversely, for example, East West installed drive trains. Manual transmissions-domin

54、ate in these vehicles in Europe. Four speed transmissions are used almost exclusively as the automatic transmission solution. The first five-speed transmission entered the market in 1998. Six2speed automatic transmission

55、s for these applications are not yet available but are u</p><p>　　Figure 8 show s a comparison between a 4-speed automatic transmission and the continuously variable transmission CFT23 from ZF on the basis o

56、f a consumption acceleration diagram. The stepped automatic transmission has a total gear ratio of itotal= 4. 14 and the CFT23 has an overall ratio of itotal= 6. 00. The calculation was completed for a mid range class ve

57、hicle with a litre cylinder internal combustion engine. From the diagram, it can be seen that a fuel saving of around 11% can be made with </p><p>　　Measurements were taken in a CFT23 in a mid-range class ve

58、hicle with a 2.4 litre 5-cylinder engine and compared with those of a 52speed automatic transmission. The initial results are shown in Figure 9. From this it can be seen that the CVT was able to increase acceleration 0 t

59、o 60 mph by 6% and fuel consumption was between 5.0 and 9.6% lower. It should be noted the continuously variable transmission with these consumption and acceleration measurements were taken and had not yet been subjected

60、 t</p><p>　　Figure 10 is based on a theoretical comparison between CVT, 52speed and 62speed automatic transmissions for a vehicle of the upper mid-range class with a 3. 0 litreV6 engine. The 52speed transmis

61、sion has a total ratio of approx. itotal = 5. 6, where the 62speedmodel and the CVT have a total gear ratio of around itotal= 6. 0. The axle configuretions were selected to ensure that virtually equivalent fuel consumpti

62、on figures are achieved in the NEDC. On the basis of a smaller engine, a comparable m</p><p>　　Fig. 7　Consumption2acceleration2diagram for 5HP24 and 6HP26</p><p>　　Fig. 8　Consumption2acceleratio

63、n2diagram for 42spee automatic and CFT23 </p><p>　　Fig. 9 　Consumption and acceleration comparison: 5-speed automatic and CFT23</p><p>　　Fig. 10　Consumption and acceleration comparison: 5- and 6

64、-speed automatic transmissions and CVT</p><p><b>　　7　Results</b></p><p>　　The comparison review s investigating fuel consumption and acceleration characteristics of passenger cars wi

65、th different automatic transmission concepts show the significant advantages of new transmission concepts presently being launched or soon to be launched as volume production models. This applies to the new generation of

66、 62speed automatic transmission with rear wheel drive in comparison with today’s standard 52speed models. The fuel consumption gain is 5 to 6% with an increase in accelerat</p><p>　　Therefore, these new auto

67、matic transmissions make a considerable contribution towards reducing fuel consumption and assist the automotive industry to significantly reduce fleet consumption and exhaust emissions. A t the same time, they offer the

68、 vehicle driver greater performance and increased drive comfort.</p><p>　　B IBL IOGRAPHY </p><p>　　[1]　H. W allentow itz and D. Neunzig, “Reduzierung der Schadstoffbelastungen”. Reduction in pol

69、lutant emissions. ATZ 103(2001)1, S. 50256.</p><p>　　[2]　Chr. Bock,“DieACEA2Vereinbarungen zur Flottenverbrauchsreduzierung und ihre moβglichen Konsequenzen auf zukünftige Getriebekonzepte”. The ACEA ag

70、reements on reductions in fleet fuel consumption and their possible implications on the transmission concepts of the future. Vortrag auf der Tagung CVT2Getriebe, Lecture at the conferenceon CVT transmissions, Haus der Te

71、chnik e. V. , Essen, 15. 216. 11. 2000.</p><p>　　[3]　G. W agner, “Application of transmission systems for different driveline configurations in passenger cars”, SAE paper 200120120882.</p><p>　　

72、[4]　G. W agner, M. Bucksch and H. Scherer,“Das automatische Getreibe ZF 6HP262Getriebesystem, konstruktiver Aufbau und mechanische Bauteile”. The ZF 6HP26 automatic transmission 2 transmission system, design and mechanic

73、al components VD I2Berichte N r. 1610, S. 6312654, VD IVerlagDüsseldorf 2001.</p><p>　　[5]　H. Mozer, “Das stufenlose Getriebe CFT23 von ZF” The continuously variable transmission CFT23 from ZF 9. Aache

74、ner Kolloquium Fahrzeug2undMotorentechnik Th 2000, 9 Aachen Colloquium on Vehicle and Engine Technology 2000, Tagungsbericht S. 119321212, Aachen, 9. Okt. 2000.</p><p>　　[6]　G. W agner,“Automatische 62Gang2G

75、etriebe für Person-enkraftwagen 2 Ein M eilenstein in der Antriebstechnik-Entw icklung”. Automatic 62speed transmissions for passenger cars-amilestone in powertrain development 21. Internationales W iener Motorensy

76、mposium 4. 25.st M ai 2000. 21 internationalV ienna Engine Symposium, M ay 425, 2000. Fortschr. 2Ber. VD IReihe 12N r. 420, Band 2, S. 1722 186. VD I2VerlagDüsseldorf 2000</p><p>　　[7]　U. Rühringer

77、, W. Danz and H. Deiss, “Stand2by2con2 trol 2eine neue Funktion inAutomatgetrieben”Stand2by control 2 a new function in automatic transmissions. VD I2Berichte N r. 1393, S. 6272644, VD I2Verlag</p><p>　　D

78、52;sseldorf 1998.</p><p>　　6 檔自動變速器和CVT 對燃油經(jīng)濟性的貢獻</p><p>　　[摘要]改善燃油經(jīng)濟性和CO2 排放水平是新型轎車開發(fā)工作中優(yōu)先考慮的問題。新開發(fā)的6 檔自動變速器和CVT 將應用在車輛上。這些變速器可完全滿足降低燃油消耗和排放的要求, 并在任何情況下都能提高駕駛舒適性。將它們于 5 檔后輪驅(qū)動和 4 檔前輪驅(qū)動自動變速器相比, 即

79、可發(fā)現(xiàn)新變速器系統(tǒng)的優(yōu)越性。在NEDC(新歐洲循環(huán)駕駛)試驗中可節(jié)約6- 8%的燃油, 而0- 60km 的加速性提高了4- 10%。</p><p><b>　　1　前言</b></p><p>　　目前在轎車開發(fā)過程中, 降低燃油消耗是檢驗新品種和新車型的一個關(guān)鍵。在歐洲, 背后的促進力來自: 1991 年德國汽車制造商自行決定在 2005年實現(xiàn)減少燃油消耗 25

80、%, 同時歐洲汽車協(xié)會(ACEA)在 1995 年建議將汽車燃油消耗降至歐洲可接受的水平。德國汽車制造商預測以汽車工業(yè)平均水平而論在14 年內(nèi)能將轎車的平均油耗從8升/100km 降到 6 升/100km , 相當于從每加侖 56. 8英里增加到每加侖75. 7 英里。ACEA 的協(xié)議建立在到 2008 年汽車的 CO2 排放將從 180g/km (112gm i)降至140gkm (87gm i) 。這樣一個雄心勃勃的目標只能通過各方

81、面的改進才能實現(xiàn)。為達到該目標, 除了改進發(fā)動機外, 傳動系統(tǒng)也應做出貢獻。作為傳動系的主要部件, 變速器尤為重要。</p><p>　　除了最低燃油消耗和高的性價比外, 在評判轎車水平方面, 駕駛舒適性正成為一個重要的依據(jù)。因此歐洲自動變速器的比例正在提高(見圖 1)。由于自動變速器各部件已標準化, 和手動變速器相比, 那些換檔元件如液力變矩器、油泵、液壓單元和摩擦片牽引損失等導致了自動變速器較高的動力損失。當

82、自動變速器裝車率不斷提高時, 獲得滿意的燃油消耗是一個特別的挑戰(zhàn)。為避免傳統(tǒng)多檔自動變速器系統(tǒng)固有的缺點,CVT 正在投入市場。由手動變速器改進而來的其它變速器系統(tǒng)也正在開發(fā)中。</p><p>　　由于不同的變速器系統(tǒng)適用于不同的轎車, 很難采用統(tǒng)一標準評判各種變速器對燃油消耗的影響。本文不涉及上述各變速器系統(tǒng)對燃油消耗影響的具體細節(jié), 但將給出所討論的變速器系統(tǒng)在改善油耗方面的潛力。本文將關(guān)注那些即將投入大批

83、量生產(chǎn)的變速器, 如標準傳動中將替代 5 檔和 6 檔手動變速器的5 檔和6 檔自動變速器以及使用在前輪驅(qū)動上的4、5、6 檔自動變速器和CVT。</p><p><b>　　2　燃油消耗和性能</b></p><p>　　歐洲 ECE 駕駛循環(huán)包括 13 的城市道路工況和 23 速度為 90kmh 和 120kmh 的穩(wěn)定行駛工況, 以該循環(huán)作油耗對比試驗已有很長時

84、間。目前新的歐洲駕駛循環(huán)(NEDC)或MVEG(機動車排放組)適用于2. 5 噸以下的車輛, 作為評價燃油消耗和排放的基礎(chǔ)(見圖 2)。這一全面的駕駛循環(huán)將作為本文評價各種變速器系統(tǒng)的基礎(chǔ)。在其它國家則采用其它的駕駛循環(huán), 如美國采用EPA 循環(huán)。不同的汽車制造商和試驗機構(gòu)所采用的特殊試驗程序不是本文考慮的對象。燃油消耗的指標是百公里油耗或每加侖的里程的絕對值, 或者轉(zhuǎn)換成百分率表示之。</p><p>　　松開

85、加速踏板(加速 4 秒鐘后的距離)、全油門加速(0- 100kmh 或60mph 所需的時間)和靈活性(從 80kmh- 120kmh 的加速時間)是目前用戶對車輛評價的重要指標, 它們將作為性能的評價標準。本文主要以全油門加速為評價標準, 將精確到秒。</p><p>　　油耗和加速曲線圖(見圖6)被用來描述油耗和性能。在節(jié)氣門全開加速時, 該曲線被用于描述車輛采用相同發(fā)動機和不同變速器時的油耗。其它參數(shù)有驅(qū)動

86、橋速比, 它也影響油耗和加速性。油耗加速曲線可以不同的形式表現(xiàn), 如用mgh (每加侖行駛里程)替代 l100km (百公里油耗)或 4 秒加速的行駛距離。而驅(qū)動橋速比也可用車輛質(zhì)量來代替。</p><p>　　本文中的油耗和加速值主要基于仿真計算。在仿真模型中, 變速器系統(tǒng)的各種損失由試驗提供, 因此真實描述了變速器的影響。為檢驗仿真結(jié)果的正確性, 將某些計算結(jié)果與試驗作了對比。表明仿真計算并不非常準確, 但相

87、對值之間的相關(guān)性非常好,因此相對結(jié)論是非常準確的。</p><p><b>　　3　變速器</b></p><p>　　過去歐洲主要采用 4 檔和 5 檔手動變速器(M T)。由于采用機械機構(gòu), 效率很高, 但隨著交通日益擁擠和對舒適性的重視, 已不能滿足許多用戶的需要。因此4 檔和5 檔自動變速器(AT)被采用。目前這些自動變速器能提供很高的駕駛舒適性, 但由于較高

88、動力損失造成較高的燃油消耗。所以除了上述變速器外, 正在或即將投入市場其它類型的變速器主要用于降低轎車油耗。</p><p>　　手動變速器的趨勢是 6 檔+ 自動換檔, 這就是所謂的機械自動變速器(AM T)。在傳統(tǒng)機械變速器上安裝液力或機電執(zhí)行機構(gòu)的AM T 系統(tǒng), 可采用換檔程序自動實現(xiàn)換檔的切換。</p><p>　　自動變速器系統(tǒng)的換檔特性是無動力中斷現(xiàn)象。在2001 年首臺6

89、檔自動變速器投入市場。除此之外, 采用鋼帶或鏈條傳遞轉(zhuǎn)矩的CVT 和由滾子傳動演變而來的錐盤式CVT 也已投入市場?；跈C械變速器的雙離合器變速器正在開發(fā)中。由于可進行動力換檔, 它們都屬于自動變速器的范疇。</p><p>　　如上所述, 對燃油消耗和駕駛性能作比較的變速器僅限于那些已大規(guī)模生產(chǎn)的和將要投入應用的產(chǎn)品。標準傳動的結(jié)構(gòu)是發(fā)動機前置后驅(qū)形式(RWD)。適用于上述轉(zhuǎn)矩范圍的6 檔手動變速器將增加。第4

90、 部分將簡單介紹該變速器對油耗和加速性的影響。歐洲RWD 車輛的變化是將 5 檔自動變速器改成6 檔。圖3 是5 檔和6 檔自動變速器的對比 。ZF 公司的5HP24 和6HP26 將在第 5 節(jié)中比較。預計CVT 將在發(fā)動機橫置的前驅(qū)車輛中增加份額, 已做了關(guān)于4、5、6 檔自動變速器和CVT 在上述車型的對比。圖 4 是 5 檔自動變速器和 ZF-CFT23CVT 的性能對比 。</p><p>　　4　6

91、檔手動變速器和燃油消耗</p><p>　　關(guān)于近年來投入市場的6 檔手動變速器燃油消耗和加速性能的報告看, 它與先期的 5 檔手動變速器相比, 雖然增加了檔位但在試驗循環(huán)中, 油耗并未降低。試驗表明, 6 檔手動變速器和 5 檔變速器相比, 油耗增加了 2%- 5%, 加速性能降低了 5%-2%。這主要由以下原因造成:</p><p>　　● 6 檔變速器所增加的速比僅為16%</

92、p><p>　　● 由于增加了齒輪數(shù)和同步器數(shù)量, 變速器功率損失高</p><p>　　● 低檔位處的速比間隔過小</p><p>　　● 試驗循環(huán)中第6 檔無明顯影響。</p><p>　　● 作為變速器和驅(qū)動橋主減速器的設(shè)計結(jié)果,發(fā)動機轉(zhuǎn)速的增加起因于在試驗循環(huán)中特殊的換檔點。</p><p>　　因此6 檔手動變速

93、器中第6 檔齒輪無助于改善油耗、排放和加速性能。</p><p>　　5　6 檔自動變速器和燃油消耗</p><p>　　ZF 5HP24 5 檔自動變速器適用的發(fā)動機轉(zhuǎn)矩為 420Nm, 因此可適用 8 缸內(nèi)燃機, 總速比為 itotal=4. 44。相比 6 檔自動變速器 6HP26 的適用轉(zhuǎn)矩達440Nm, 總速比為 itotal= 6. 04。所增加的速比(約36%)明顯降低了油耗

94、。由Lepelletier 行星齒輪機構(gòu)組成的主機械傳動的效率高達 99%以上。除此之外, 在變速器的開發(fā)過程中許多具有進一步降低油耗潛的優(yōu)化措施已被采納 。以下措施需特別提及:</p><p>　　● 開發(fā)了新型變排量轉(zhuǎn)子泵, 減少了泄漏和機械損失。</p><p>　　● 通過減少泄漏特別是在液壓控制系統(tǒng)中的泄漏, 優(yōu)化了潤滑油供給。</p><p>　　● 優(yōu)

95、化了變速器中的油道以減少牽引損失。</p><p>　　● 使用高效的潤滑油, 特別在工作溫度低時能減小潤滑油的牽引損失。</p><p>　　● 改善變矩器鎖止離合器的性能, 使之能在低車速時使用。</p><p>　　● 改進了換檔元件的尺寸以利于待機控制(stand2by2control) (空檔怠速)。</p><p>　　● 除了經(jīng)

96、濟模式外, 優(yōu)化了自適應換檔模式,可根據(jù)駕駛員類型和駕駛風格加以調(diào)整。</p><p>　　其結(jié)果見圖 5, 對配備 4. 4 升 8 缸內(nèi)燃機和主減速器的中高檔車輛油耗仿真表明, 由于總速比較大, 能降低約2%的油耗。而上面所提到的那些優(yōu)化措施和新潤滑油也能降低 2%的油耗。如果采用了待機控制 , 又能降低 2%的油耗。因此 6HP26 與5HP24 相比在NEDC 循環(huán)中可降低5%- 6%油耗。</p&

97、gt;<p>　　同時從圖 6 中可知, 0- 100kmh 加速時間縮短了0. 3 秒, 提高了4%。4 秒后的距離增加了3. 1m或9%, 這對任何轎車而言都有半個車長。</p><p>　　結(jié)論可用油耗加速曲線描述, 這里根據(jù)不同的主減速比對6HP26 作了仿真計算(見圖6)。根據(jù)歐洲的情況, 曲線左側(cè)底部是最佳方案。該曲線表明加速性能相同時所選的后橋速比(iRAR = 3. 15)對減少油耗

98、的貢獻。如采用更大的主減速比, 還能進一步提高加速性, 但會減少對油耗的好處。圖7 是以美國慣例作出的油耗加速曲線, 最佳點在曲線的右上方。</p><p>　　6　CVT 和燃油消耗</p><p>　　目前絕大部分小型轎車、低檔中型轎車和中型轎車采用發(fā)動機變速器橫置驅(qū)動方式, 例如東歐的轎車。在歐洲手動變速器在這些車輛中占有主導地位。毫無疑問4 檔變速器會被自動變速器替代。第一臺5 檔

99、變速器于1998 年進入市場。雖然尚無6 檔自動變速器應用于這些車輛, 但它們正在開發(fā)中CVT 已占領(lǐng)了很大一部分市場, 還有更多的產(chǎn)品正處于開發(fā)中。</p><p>　　圖8 是ZF CFT23 CVT 和4 檔自動變速器油耗加速曲線的比較。自動變速器的總速比itotal= 4.14, 而CFT23 的速比itotal= 6. 00。計算時所用車輛為中型轎車, 配備2. 0 升4 缸內(nèi)燃機。從曲線中可知,CVT