一般來說，排量區(qū)區(qū)1.0L的3缸汽油發(fā)動機可能并不是氣缸鈍化技術(shù)“大展拳腳”的最佳舞臺，但福特（Ford）卻有意打破常規(guī)，計劃在2018年推出一款應(yīng)用氣缸鈍化技術(shù)的EcoBoost 3缸發(fā)動機。簡單來說，氣缸鈍化技術(shù)可以讓這款3缸發(fā)動機在特定負(fù)載條件下轉(zhuǎn)為一款670cc的雙缸發(fā)動機，預(yù)計該技術(shù)可將車輛的燃料經(jīng)濟性提升6%，并取得一定程度的減排效果。
福特表示，這款EcoBoost將成為世界首款采用氣缸鈍化技術(shù)的3缸發(fā)動機。與一些懷疑論者的看法不同，福特堅信氣缸鈍化技術(shù)完全可以滿足3缸發(fā)動機的改進與NVH要求。
在氣缸鈍化技術(shù)的協(xié)助下，EcoBoost發(fā)動機可以在巡航或輕負(fù)載條件下進入雙缸模式，從而優(yōu)化車輛能效。福特聲稱，當(dāng)環(huán)境發(fā)生變化時，EcoBoost可在14毫秒內(nèi)重回3缸模式，具體時長則取決于節(jié)流閥的具體位置。
福特全球動力系統(tǒng)工程副總裁Bob Fascetti表示，氣缸鈍化版EcoBoost展示了汽油發(fā)動機技術(shù)的持續(xù)研發(fā)潛力。
之前，福特還曾與舍弗勒集團（Schaeffler Group）共同合作研發(fā)了一款可變排量系統(tǒng)。該系統(tǒng)經(jīng)過專門設(shè)計，可利用油壓激活一款特殊的氣門搖臂，斷開曲柄與一個氣缸間的連接，最高轉(zhuǎn)速可達4500轉(zhuǎn)。福特的工程師透露，與EcoBlue柴油發(fā)動機采用的曲柄很類似，這款一件式曲柄模塊也可以在氣缸頭位置騰出更多空間，用于新油路和閥門轉(zhuǎn)換組件的設(shè)計安裝。
此外，這款常規(guī)發(fā)動機還采用了新型雙質(zhì)量飛輪和減振離合盤，從而解決雙氣缸模式下的發(fā)動機振動問題。這種設(shè)計必不可少，否則發(fā)動機的振動將比較明顯，特別是在低轉(zhuǎn)速的情況下。福特的工程師表示，系統(tǒng)活動時的進氣閥和排氣閥均處于關(guān)閉狀態(tài)，這可以將氣體封在氣缸內(nèi)部，產(chǎn)生“彈簧效應(yīng)”，從而協(xié)助保持氣缸的受力平衡和內(nèi)部溫度，隨時為重新激活做好準(zhǔn)備。
除此之外，該系統(tǒng)還采用了新的發(fā)動機支架、傳動軸、懸掛襯套、凸輪軸鏈，以及金屬注塑成型工藝的氣門搖臂。
2015年，福特在歐洲市場的新車銷售中，有20%的車輛（具體來說，共有11款車型）采用了這款1.0L的3缸發(fā)動機。
目前，福特并未透露氣缸鈍化技術(shù)會給發(fā)動機增加多少成本，也未表明增加的成本是否會反映到最終用戶的購車價格中。
A 1.0-L three-cylinder gasoline engine may not seem a likely candidate for cylinder deactivation, but Ford is doing just that with diminutive EcoBoost triple. Production is slated to begin by early 2018 with the technology—which turns the engine into a 670-cc twin under certain load conditions—expected to deliver up to a 6% fuel saving with associated CO2 emissions reduction.
Claimed as a “world first” for a triple, Ford believes its deactivation technology will meet refinement requirements and confound skeptics that such a system applied to a 3-cylinder engine would be unacceptable in NVH terms.
The EcoBoost effectively enters twin-cylinder operation in some cruise and light engine load conditions. Depending on throttle position it reverts to 3-cylinder operation when conditions change—in a claimed 14 ms.
According to Bob Fascetti, Vice President Global Powertrain Engineering, the development demonstrates the continuing potential of gasoline engine technology.
Ford worked with Schaeffler Group on the variable displacement system, which will operate up to 4500 rpm, using oil pressure to activate a special valve rocker to interrupt the connection between the camshaft and one cylinder. Ford engineers reveal that a single-piece camshaft module similar to that used for its EcoBlue diesel provides added space in the cylinder head for new oil channels and the valve switching components.
Further changes to the regular engine include the use of a new dual-mass flywheel and a vibration damping clutch disc to help counter engine oscillations set up in twin-cylinder mode that would otherwise manifest vibration, particularly at low revs. Intake and exhaust valves are closed when the system is active, trapping gases to provide a “spring effect” to help balance forces across all cylinders and to retain temperatures inside the cylinder to ensure fuel efficiency when reactivated, engineers report.
Also included in the system are new engine mounts, drive shafts and suspension bushes, a new camshaft chain and metal-injection-molded valve rockers.
About 20% of all Ford models sold in Europe during 2015 used the 1.0-L triple, which can be specified for 11 models sold there.
Ford gave no indication as to what the cylinder deactivation system will add to unit cost, nor how much, if any, of that would be passed to the end-user.
Author: Stuart Birch
Source: SAE Automotive Engineering Magazine
福特的1.0L 3缸發(fā)動機采用了氣缸鈍化技術(shù)，可在特定負(fù)載環(huán)境下轉(zhuǎn)為一個670cc的雙缸發(fā)動機，這能有效優(yōu)化燃油能效并降低排放。
