ZF8HP新一代自動變速器

試驗 檢測

ZF8HP新一代自動變速器

本文介紹了ZF公司新一代8速自動變速器技術(shù)的發(fā)展過程，該型變速器在緊湊化、低轉(zhuǎn)速化、啟停系統(tǒng)和滑行模式等方面具有突出的優(yōu)勢。

［Abstraet］This paper introduces a new generation eight-speed ZF automatic transmission technology development process，this type of transmission has outstanding advantages in the downsizing，downspeeding，start-stop system and coasting function，etc.

自動變速器 緊湊化 低轉(zhuǎn)速化 啟停系統(tǒng) 滑行模式

1 簡介

過去的幾十年中，自動變速器技術(shù)一直在穩(wěn)步發(fā)展，燃料消耗及二氧化碳排放量在下降（圖1）。

新一代8HP自動變速器在改善乘坐舒適性和動力性方面的同時，具有更高的節(jié)能和二氧化碳減排的潛力：成功的8HP 8速自動變速箱在2009年開始生產(chǎn)以來就已定制具備這些優(yōu)點。當前在第二代中所有這些優(yōu)點更為顯著并且自2014年7月在寶馬一些系列（5系；X5，X6）上首次實現(xiàn)量產(chǎn)。新8 HP（圖2）提供了包括更低拖曳扭矩、更寬速比范

1 Introduetion

During the past decades，the technology of automatic transmissions has been steadily increased and fuel consumption and CO2 emissions have been decreased（Fig.1）.

圖1 自動變速器的技術(shù)發(fā)展Fig.1 Technological Trend of Automatic Transmissions

Higher savings potential in terms of consumption and CO2combined with increased ride comfort and dynamics：The successful 8HP 8-speed automatic transmission has been characterized by these advantages since the start of production in 2009.All of the advantages are now even more pronounced in the second generation that initially is in volume production since July 2014 in several BMW-applications（5er；X5，X6）.The new 8HP（Fig.2）offers comprehensive further developments that range from lower drag torques and higher spread through to an improved torsional vibration absorption.Through many further developments，the 8HP is significantly more efficient compared to the predecessor transmission-up to three percent in total.

The new 8HP entered volume production at the start of July as the 8HP50 version that is designed for torques of up to 500 Nm.In the future，the 8HP75 will be part of the ZF portfolio for drives with even higher torque of up to 750 Nm.＝＞8HP75 launched already in August 2014！圍以及更優(yōu)扭振吸收新能的全面技術(shù)改進。經(jīng)過多階段的提升發(fā)展，8HP相比之前的變速器效率更為顯著-總共高達3%。

圖2 新8HP剖面圖Fig.2 Cross Section of the new 8HP transmission

7月初新8HP以8HP50版本進入批量生產(chǎn)，其設(shè)計扭矩高達500牛米。未來具有更高扭矩性能的750牛米8HP75將被列入ZF驅(qū)動系產(chǎn)品目錄。＝＞8HP75已在2014年八月量產(chǎn)！

2 緊湊化及低轉(zhuǎn)速優(yōu)化

全新的8速自動變速器結(jié)合了許多技術(shù)改進：首先，ZF進一步優(yōu)化了新變速器的運算以適應(yīng)現(xiàn)代發(fā)動機技術(shù)的要求。其發(fā)端為內(nèi)燃發(fā)動機界由于需要在不損失扭矩和性能前提下滿足即將實施的二氧化碳排放法規(guī)而形成的兩個中心趨勢：緊湊化，即具有更少氣缸數(shù)及更小排量的渦輪增壓發(fā)動機，以及低轉(zhuǎn)速化，即在低轉(zhuǎn)速區(qū)盡早達到最大扭矩。

圖3 8 HP換擋組合及傳動比級差→更高的傳動比范圍7.8Fig.3 8HP Shift Pattern and ratio Steps→Increased Ratio Coverage 7.8

2 Optimized for downsizing and downspeeding

The new 8-speed automatic transmission combines many technological advances：Above all，ZF has further optimized the new transmission generation for the requirements of modern engine technology.This is due to the fact that，in order to meet the forthcoming CO2emission specifications without losses in terms of torque and performance，there are two central trends when it comes to combustion units：Downsizing，which means turbocharged engines with fewer cylinders and less engine displacement and downspeeding，which is the reduction of the engine speeds combined with a maximum torque that is applied at a very early stage.

It is the reduction of the speeds in particular that demands transmissions with a higher spread which is the reason why ZF has increased it from 7.1 to 7.8 on the new 8HP by means of optimized gearsets.

This measure alone reduces the speed across all gears by 50 revolutions per minute on average and reduces fuel consumption by almost one percent.Furthermore，the ZF developers have succeeded in once again reducing the internal transmissionlosses.This is primarily ensured by the new multidisk separation（Fig.4）：Additional springs integrated into the multidisk packages of the shift elements ensure that the friction shift elements are almost fully opened and，consequently，cause less drag torque.Compared to the first 8HP model range，the power losses have been reduced by more than two-thirds with the new generation.

發(fā)動機轉(zhuǎn)速的降低尤其要求變速器具有更寬的速比范圍，這就是ZF在新8HP通過優(yōu)化齒輪機構(gòu)的設(shè)置、把速比范圍從7.0增加到7.8原因。

這項措施降低了所有檔位上平均50轉(zhuǎn)每分鐘的轉(zhuǎn)速和近1%的油耗。此外，ZF開發(fā)人員成功地再次降低了內(nèi)部傳輸損耗。這主要歸功于新的多重摩擦片分離（圖4）技術(shù)：集成到換擋元件多片組合包的附加彈簧確保了在換擋摩擦元件的幾乎完全分離，并因此降低了開放離合器的拖拽損失。相比第一代8HP系列，新一代功率損耗減少了超過三分之二。

圖4 多重摩擦片分離A，BFig.4 Multidisk Separation A，B

同時，進一步的創(chuàng)新功能最大限度地減少了蠕行扭矩：減速時和當車輛靜止時，其中一個離合器現(xiàn)已完全開放。其結(jié)果是，不再需要通過“制動”來阻止前行。另一個正面的結(jié)果是ZF自動變速器的油泵工作的系統(tǒng)壓力從5巴減小為至3.5巴，因此總體上需要的能量更少。

圖5 DAT-液力變矩器Fig.5 DAT-Torque Converter

此外，我們的目標是要考慮到經(jīng)濟性更好而尺寸更緊湊的新型發(fā)動機不同的振動特性。因此，所有的8HP自動變速器設(shè)有特別先進的扭振阻尼器：這些阻尼器以特別有效的表現(xiàn)消除了發(fā)生至發(fā)動機中的振動，使它們不會進一步向驅(qū)動系后端及車

Meanwhile，a further innovative function minimizes the creeping torques：A clutch is now fully opened during deceleration and when the vehicle is stationary.Consequently，it is no longer necessary to＇brake＇against the drive.Another positive effect is that the oil pump belonging to the ZF automatic transmission works with a system pressure that has been reduced from 5 to 3.5 bar and，as a result，requires less energy overall.

Furthermore，the objective was to take the changing vibration behavior of the increasingly economical yet，at the same time，more powerful downsizing units into account.Therefore，all 8HP automatic transmissions feature particularly advanced torsional vibration dampers：These dampers eliminate the vibrations that occur on the engine side in a particularly effective manner so that they are unable to move further along and into the driveline and the body.The newly developed torque converter contributes to downspeeding because the hydrodynamic transmission of power can be bridged even more quickly-this enables traveling with a closed lock-up clutch at an early stage and at an extremely low engine speed.

3 Optimized start／stop and eoasting funetion

The tailored，fuel-efficient uncoupling of the transmission in connection with a temporary engine stop，the so-called coasting function，is now possible at speeds up to 160 km／h.At the other end of the speed scale，ZF has further optimized the optional start／stop function of the 8HP：After the vehicle has come to a stop，it stops the engine without any discernible delay-instead of after 1.5 seconds as was previously the case.身傳遞。新開發(fā)的液力變矩器對低速化有顯著貢獻，因為它能使動力傳遞路徑更快地實現(xiàn)硬連接---這使得車輛能行駛在更早結(jié)合的鎖止離合器及極低的發(fā)動機轉(zhuǎn)速條件下。

3 優(yōu)化的發(fā)動機自動啟停系統(tǒng)和滑行節(jié)能模式

在發(fā)動機臨時停機時啟動的定制發(fā)動機解耦節(jié)油功能，即所謂的滑行節(jié)能模式，現(xiàn)在可在高達160 km／h車速下實現(xiàn)。在速度范圍的另一端，ZF對8HP的發(fā)動機自動啟停系統(tǒng)做了進一步的優(yōu)化：在車輛停止時，系統(tǒng)在停止發(fā)動機時并無明顯的延遲---而不像之前的情況，會產(chǎn)生1.5秒的延遲。

盡管如此，在帶來巨大節(jié)油潛力的同時，動力性能沒有受到忽視：除其他方面外，新的變速器控制單元能夠嵌套多級降檔，其使得8HP在有必要時可作出更自發(fā)和動態(tài)的響應(yīng)。

4 總結(jié)與結(jié)論

變速器技術(shù)曾經(jīng)并正在隨燃油效率的改善而不斷發(fā)展。

ZF 8HP自動變速器在高效的基礎(chǔ)上又做了進一步優(yōu)化，以提高燃油效率。為實現(xiàn)這一目標采取一些不同的措施。這些包括：

·多重摩擦片分離A／B

·降低蠕行扭矩

·轉(zhuǎn)速降低50轉(zhuǎn)每分鐘

·更高的傳動比范圍／

·阻尼系統(tǒng)

·發(fā)動機啟停系統(tǒng)

實現(xiàn)的燃料效率見圖7。

圖6 發(fā)動機自動啟停系統(tǒng)帶來的燃油效率優(yōu)化Fig.6 Fuel Efficiency Benefit by Engine Start Stop（ESS）

However，dynamics is not neglected despite the great fuel-saving potential：Amongst other things，the new transmission control unit enables nested multiple downshifts which permits the 8HP to respond in an even more spontaneous and dynamic manner where necessary.

Summary&Conelusions

Transmission technology evolution was and is driven by fuel efficiency improvement.

New Generation of ZF’s 8HP Automatie Transmission

Anton Locher，Dr.Rolf Gall，Rudolph Baumann，陳燁，葉惟人
ZF Friedrichshafen AG，Germany
Anton Locher，Dr.Rolf Gall，Rudolph Baumann，Chen Ye，Ye Weiren ZF Friedrichshafen AG，Germany

Automatic Transmission Compact Design Start-Stop System Coasting Function

圖7 變速器技術(shù)的改進-在NEDC條件下燃油效率的改進Fig.7 Transmission Technology Improvements-Fuel Efficiency Improvements in NEDC

U463.212

B

1006-8244（2014）03-03-04