五年前還很少有人會(huì)預(yù)料到，2017年全球汽車動(dòng)力總成、傳動(dòng)系統(tǒng)和燃料領(lǐng)域的格局會(huì)如此多樣化。然而如今，幾乎所有人都認(rèn)為，無(wú)論是要達(dá)到歐洲、北美以及亞洲等地區(qū)最新的減排標(biāo)準(zhǔn)，還是要達(dá)成更為長(zhǎng)遠(yuǎn)的電動(dòng)化目標(biāo)，發(fā)展各種類型的混合動(dòng)力汽車都十分重要。
在博格華納動(dòng)力驅(qū)動(dòng)系統(tǒng)公司（BorgWarner PowerDriveSystems）產(chǎn)品戰(zhàn)略部總監(jiān)John Barlage看來(lái)，“從熄火-啟動(dòng)系統(tǒng)一路發(fā)展到純電動(dòng)汽車，我們將這一歷程視作‘電動(dòng)汽車進(jìn)化史’。”和其他動(dòng)力系統(tǒng)一級(jí)制造商的規(guī)劃師所見(jiàn)略同，他也認(rèn)為下一個(gè)周期（2019年-2021年）中，更多車輛將會(huì)搭載48V混合動(dòng)力系統(tǒng)，且“數(shù)量將會(huì)相當(dāng)龐大”。
從已經(jīng)登陸歐洲的48V系統(tǒng)來(lái)看，這些產(chǎn)自?shī)W迪及其他德國(guó)整車廠的系統(tǒng)都能提供強(qiáng)大的車載電力，通過(guò)電動(dòng)增壓等方式很好地達(dá)到節(jié)能減排的效果，并能為自動(dòng)駕駛輔助系統(tǒng)（ADAS）傳感套件提供高達(dá)3千瓦的電能。
Barlage信心滿滿地表示，“由于48V系統(tǒng)的經(jīng)濟(jì)效益非常吸引人，將會(huì)很快在北美車型上普及。”談及這一技術(shù)，業(yè)內(nèi)普遍認(rèn)為，只需要普通（功率分流）混合動(dòng)力系統(tǒng)約30%的成本，就能獲得相當(dāng)于其70%的性能。博格華納的工程師還認(rèn)為，隨著系統(tǒng)架構(gòu)和封裝技術(shù)不斷升級(jí)，48V甚至更高電壓的混合動(dòng)力模塊都將進(jìn)行研發(fā)，以實(shí)現(xiàn)P2架構(gòu)的應(yīng)用。
在P2布局中，電機(jī)將會(huì)置于內(nèi)燃機(jī)和變速箱之間（詳見(jiàn)圖解）。其他行業(yè)認(rèn)可的混合動(dòng)力架構(gòu)布局（從前到后依次）包括：P0（主要為履帶-交流電機(jī)-起動(dòng)機(jī)構(gòu)，簡(jiǎn)稱“BAS”）；P1（例如位于飛輪位置的本田IMA）；P3（電機(jī)置于主減速器前的變速箱輸出軸上）；以及P4（也被稱為四輪驅(qū)動(dòng)混合動(dòng)力架構(gòu)，采用后橋電動(dòng)驅(qū)動(dòng)方式）。除P2外，其他幾種方式都具有扭矩矢量控制功能。
Barlage注意到，“對(duì)傳動(dòng)系統(tǒng)而言，P2架構(gòu)的出現(xiàn)帶來(lái)了很多良機(jī)，包括能和雙離合變速器（DCT）甚至自動(dòng)離合裝置配合工作（詳情請(qǐng)參閱： http://articles.sae.org/15576/），同時(shí)也非常適合插電式混合動(dòng)力車。P2配置下的插電式混合電動(dòng)車（PHEV），在純電動(dòng)模式下的整體能效，甚至要高于混動(dòng)模式。如果想要打造適合高速公路駕駛的電動(dòng)車，或?qū)崿F(xiàn)卡車的電動(dòng)化，P2架構(gòu)一定是首選。
同軸和異軸
“在其他的48V應(yīng)用架構(gòu)研發(fā)中，我們選擇首先從P0開(kāi)始。”博格華納高級(jí)工程部的技術(shù)研究員JoelMaguire 說(shuō)，“這樣可以將同樣的電機(jī)用于各個(gè)不同位置，能夠產(chǎn)生規(guī)模效應(yīng)。”
Maguire告訴《國(guó)際汽車工程》（AutomotiveEngineering International）記者，他的產(chǎn)品研發(fā)小組根據(jù)OEM的各項(xiàng)需求，對(duì)應(yīng)用于P2, P3或P4型混合動(dòng)力系統(tǒng)的電機(jī)電磁材料進(jìn)行優(yōu)化，從而設(shè)計(jì)出了“一系列滿足OEM汽車封裝要求的，結(jié)構(gòu)緊湊、動(dòng)力強(qiáng)勁的電機(jī)，而有些（競(jìng)爭(zhēng)對(duì)手的）功率分流型的產(chǎn)品，甚至有些P2架構(gòu)，也必須在設(shè)計(jì)上做出一些妥協(xié)，因?yàn)槠滠嚱Y(jié)構(gòu)的靈活性和現(xiàn)有的汽車封裝技術(shù)而言，還并不能很好地配合48V硬件設(shè)備。”
博格華納P2架構(gòu)的一大特點(diǎn)，就是其167毫米（合6.57英寸）的軸向長(zhǎng)度。根據(jù)公司內(nèi)部數(shù)據(jù)顯示，這一長(zhǎng)度下的額定最大扭矩可以超過(guò)330牛·米（合243磅·英尺），最大功率則能超過(guò)80千瓦（合107馬力）。無(wú)論是同軸（指和變速箱輸入軸、發(fā)動(dòng)機(jī)曲軸以及扭矩減震器位于同一根軸上）還是異軸，這一模型都適用。而對(duì)于異軸而言，由于其安裝位置在驅(qū)動(dòng)橋箱上方，因此這也算是一種傳動(dòng)鏈驅(qū)動(dòng)的解決方案，可以滿足較小的橫置發(fā)動(dòng)機(jī)/前輪驅(qū)動(dòng)車輛的封裝要求。
“空間上的節(jié)省主要在車輪之間，同時(shí)由于軸長(zhǎng)不變，因此可以避免可能發(fā)生的機(jī)械損壞。”Maguire解釋道，“這一模型棄用了交流電機(jī)，可以將空調(diào)壓縮機(jī)整合到同一個(gè)鏈傳動(dòng)裝置上，在發(fā)動(dòng)機(jī)關(guān)閉時(shí)，仍可以用48V系統(tǒng)讓空調(diào)保持運(yùn)轉(zhuǎn)。”
上述兩種P2模塊中都包含一個(gè)分離式離合器，置于電機(jī)和雙質(zhì)量飛輪的集成結(jié)構(gòu)內(nèi)，可以與當(dāng)下最流行的傳動(dòng)技術(shù)搭配使用，其中包括行星齒輪步進(jìn)式自動(dòng)變速箱，雙離合變速器（DCT）、無(wú)級(jí)變速器（CVT）以及自動(dòng)換擋系統(tǒng)等。博格華納的工程師指出，P2架構(gòu)的另一大優(yōu)勢(shì)就是：可以繼續(xù)使用目前已有的發(fā)動(dòng)機(jī)和傳動(dòng)系統(tǒng)。
“采用了P2架構(gòu)，就可以在發(fā)動(dòng)機(jī)和變速箱之間加入一個(gè)模塊。當(dāng)然，這一方案并非絕對(duì)理想。”Barlage說(shuō)，“但同專門(mén)用于混合動(dòng)力的變速器相比，這仍是更經(jīng)濟(jì)的選擇，涉及的調(diào)整也會(huì)少很多，而且還能改變尺寸大小。”而在配合DCT的配置時(shí)，使用P2架構(gòu)則可以成為三離合器布置，也就是博格華納所說(shuō)的“K-Zero”系統(tǒng)，其中包括了連接到電機(jī)的分離式離合器，以及負(fù)責(zé)在兩套齒輪組之間進(jìn)行切換的K1和K2離合器。
Maguire特別指出，“我們的戰(zhàn)略規(guī)劃是要玩轉(zhuǎn)各種驅(qū)動(dòng)架構(gòu)涉及，從P0到P4都能應(yīng)用自如。而通過(guò)觀察OEM對(duì)各種混合動(dòng)力驅(qū)動(dòng)架構(gòu)的探索，以及不斷的學(xué)習(xí)研究，我們已經(jīng)打造出了一套可用于各種設(shè)計(jì)布局的系統(tǒng)。”
Five years ago, few predicted the high level of fragmentation in powertrains, drivelines and fuels that exists in 2017. Nearly everyone now agrees, however, that Hybridization of all types is essential to meeting the latest European, North American and Asian emissions regulations and in bridging toward the long-term electric future—whenever that comes.
“We see it as a ‘spectrum of electrification’ from stop-start systems all the way to pure EV—and everything’s in play,” observed John Barlage, Director of Product Strategy, of BorgWarner PowerDrive Systems. Like other Tier 1 powertrain systems planners, he sees “very large volumes” of 48V hybrid applications coming in the next (2019-2021) cycle.
Already arriving in Europe from Audi and other German OEMs, the 48V systems provide greater on-board electrical power for CO2-reducing features such as e-boosting, and for ADAS (automated driver assistance systems) sensor suites which can gobble up to 3 kW.
“We’re going to see North America adopt 48V because it has such interesting economics,” Barlage asserted. The technology is often described as delivering about 70% of the performance of a conventional [powersplit-type] dedicated hybrid for about 30% of the cost. BorgWarner engineers also considered system architecture and packaging in developing a broad new portfolio of 48V and higher voltage hybrid-power modules aimed at P2 (position 2) applications.
In the so-called P2 location, the electric motor is located between the combustion engine and transmission; see diagram. The other industry-recognized hybrid positions include (starting from the front of the vehicle) P0 (belt-alternator-starter ‘BAS’); P1 (such as Honda’s IMA in the flywheel position); P3 has the motor on the transmission output shaft ahead of the final drive, and P4 (electric rear axle drives) often called ‘through the road’ AWD hybrids. The latter also offers torque-vectoring capability.
“P2 offers a lot of very interesting driveline opportunities,” Barlage observed, “including paired with dual-clutch (DCT) and even automated-clutch manuals [see http://articles.sae.org/15576/]. It also presents a very nice combination for plug-in hybrids. A P2 with PHEV capability actually delivers better overall efficiency in pure electric mode than a powersplit type does. If you want to go on the autobahn in electrically, or want to electrify a truck, you want a P2 type hybrid.”
On- and off-axis
“P-Zero ‘BAS’ systems were the starting point of our development with the same 48-V motor module used in the other positions,” explained Joel Maguire, BorgWarner’s Technical Fellow, Advanced Engineering. The engineering strategy “has economies of scale by applying a common electric machine across the locations.”
The product development team designed what Maguire calls “a nice, compact motor-generator ‘form factor’ based on a broad set of OEM vehicle-packaging requirements,” optimizing use of the e-motor’s magnetic material for P2, P3 or P4 applications, depending on what the OEM needs. “Some [competitors’] powersplit and even P2 architectures have had to compromise because their hardware wasn’t so ‘comfortable’ in terms of its flexibility with the existing vehicle package,” he told Automotive Engineering.
BorgWarner’s P2 module features an axial length of 6.57 in (167 mm). Rated peak torque is greater than 330 N·m (243 lb·ft). Peak power is greater than 80 kW (107 hp), according to the company. It is engineered for both on-axis (meaning located on the same axis as the transmission input shaft, engine crankshaft and torsional damper) and off-axis fitments. The latter, mounted piggyback on the transaxle case, is a chain-driven solution designed for the tight packaging needs of smaller transverse-engine/front drive vehicles.
“The key savings is the space from wheel to wheel; it avoids potential tear up, with zero length in axial growth,” Maguire explained. “You eliminate the alternator and can integrate the AC compressor on the same chain drive and can still run the compressor off the 48V when the engine is off.”
Both P2 modules include a disconnect clutch nested within the e-motor and an integrated dual-mass flywheel, enabling integration with popular transmissions: planetary step-type automatics, DCTs, continuously variable (CVTs) and automated manuals. The BorgWarner engineers note another P2 advantage: re-use of the existing engine and transmission.
“With P2 you’re dropping a module in between the engine and trans. For sure, it’s not a perfectly ‘clean’ addition,” Barlage said. “But compared with a dedicated hybrid transmission it’s still less expensive and requires a lot less modification. And it’s scalable.” Engineered into a DCT, the P2 unit becomes a triple-clutch arrangement or what BorgWarner calls ‘K-Zero’ with the disconnect clutch connected to the e-motor and the K1 and K2 clutches handling the shifting between the two gear clusters.
“Our strategy is to play in all architectures, from P-Zero to P4, so as we see OEM movement into any of the hybrid positions, we’ve got a system engineered for them all,” Maguire noted.
Author: Lindsay Brooke
Source: SAE Automotive Engineering Magazine
“P”代表產(chǎn)品已進(jìn)入預(yù)備階段：圖中的P0到P4，都是博格華納目前正在研發(fā)中的電動(dòng)推進(jìn)系統(tǒng)架構(gòu)。（圖型來(lái)源：博格華納）
博格華納高級(jí)工程部門(mén)的技術(shù)研究員Joel Maguire表示，公司的戰(zhàn)略規(guī)劃就是要“玩轉(zhuǎn)各種混動(dòng)架構(gòu)”。（圖片來(lái)源：博格華納）