[F1] Honda RA618H PU架構解析

幾週前的 F1 日本GP，Honda 依照慣例在鈴鹿賽道展示了 F1 動力單元(Power Unit, 簡稱PU)。
而國外媒體 f1i.com 也藉此機會，分析了 Honda 今年賽季所使用的 PU：「RA618H」



從俄羅斯GP到日本GP這一個星期間，可以看到有些許的技術提升出現在鈴鹿賽道上。而這第17場F1錦標賽中，我們有一個很好的機會來觀察 Honda 最新版本的 PU。

這在旭日升起之地已經成為一個傳統：在身為主場的鈴鹿賽道，Honda 展示了使用於 STR13 身上的動力心臟「RA618H」。



這具日本V6 PU保留了前代的分離式架構，渦輪和增壓器為分離狀態，並透過安裝 MGU-H 的軸連接。從 2017 年開始，增壓器不再設置於V型汽缸底部，而是採取類似 Mercedes V6 置於前方的形式。這種方式可以增加增壓器體積，並提高動力輸出，但也因此要被迫重新設計油箱。

從上圖可以看到，增壓器透過潛望鏡形狀的碳導管供給空氣，藉由導管穿過油箱，送到中間位置（黃色箭頭處）。壓縮和冷卻過後的空氣（已通過中冷器），從頂部有兩個進氣口（紫色箭頭處）進入集氣箱。再來可以看到其中一個直噴幫浦（紅色箭頭處），而透過凸輪軸的驅動，這些幫浦各自可以提供 500 bar 的壓力給噴油嘴。再往下看，則是負責傳輸AC電力給控制盒的三相線組（橘色部分），主要是將電力轉換成直流電，並讓電池充電。綠色箭頭處的線組連接 MGU-H 到控制單元，而控制單元再透過藍色線組連結 MGU-K。

來到 PU 後端，可以看到這個日本V6在黃色箭頭處的部件為集氣箱，藍色箭頭處則為兩個排氣管，紅色箭頭為渦輪，下方綠色箭頭所指的黑色蓋板內則為離合器。



在 Honda 的架構下，離合器是設置於 PU 端，而非在變速箱側。由於 V6 Turbo 引擎的轉速較低（限轉於 15,000 rpm），讓離合器安置於引擎端是可行的，這種方式在過往已經經過驗證，而且相較於先前的大排量V8，扭力表現有顯著地提升。而 Mercedes 也是採用相同的配置。

在鈴鹿賽道，我們也捕捉到了一個不錯的視角，這個日本 V6 的電池組似乎非常緊湊，尤其是和 Ferrari SF71H 相對比，更是如此。



在 Montreal 發表 Spec 2 之後，Honda 一直到了 Sochi 才正式發表了 Spec 3 的 RA618H。雖然輸出更為有力，但這個版本也讓兩位車手在駕駛面上遭遇到一些問題，扭力有時會在沒有預期的狀況下進行輸出。這也是 Gasly 和 Hartley 要在俄羅斯GP 換回前一個版本 PU 的原因。

為了解決這個問題，Honda 進行了 dyno-test 和最佳化，改進扭力傳輸。藉此減緩從變速箱產生的振動。

然而這問題似乎沒有完全的解決，因為 Gasly 在週六的自由練習曾回報過，在升檔時有嚴重的振動，導致排位賽需採取較為保守的模式。為了解決這個問題，Honda 曾獲得 FIA 的許可，在 Parc Fermé 更換部分零件。但又因為某些因素，FIA在正賽起跑前，又表示反悔，要 Toro Rosso Honda 換回原先的設定。



儘管有這些插曲，但透過排位賽的表現，動力的提升是有目共睹且毋庸置疑的。「從性能的角度來看，我們是很開心的。也許是低轉速時的一些扭矩傳遞，造成換擋後的振盪，我們將會去評估從這裡得到的數據，並在接下來比賽進行改善。」Honda技術總監田辺豊治解釋道。

當然，動力總成的可靠度還未最佳化，動力也許是和 Renault 在同一個層級。但儘管如此，自從和 Toro Rosso 合作後，這家日本製造商可以在一個較為冷靜的環境進行工作並逐漸進步，並以較好的方式從可能的錯誤吸取經驗。



原文：
Tech F1i: Honda gets a boost at home

With just a week between the Russian and Japanese Grands Prix, there were logically few technical evolutions implemented at Suzuka. However, the 17th round of the F1 world championship did offer a good opportunity to get a closer look at Honda’s latest-spec power unit.

ON HOME TURF
It has become a tradition in the Land of the Rising Sun: at its home race at Suzuka, Honda put its engine on display, exposing the layout of the RA618H that powers the Toro Rossos of Pierre Gasly and Brendon Hartley.

The Japanese V6 has retained the split architecture of its predecessors: turbine and compressor are dissociated and connected by a shaft on which is mounted the MGU-H. Since 2017, the compressor is no longer housed inside the "V" formed by the two banks of cylinders, but is installed at the front of the block, like the Mercedes V6. This positioning helped increase the size of the compressor and therefore the power, but it forced a redesign of the fuel tank, hollowed out like its counter-part on the Anglo-German engine.

As can be seen in the picture above, the compressor is fed with air by a periscope-shaped carbon duct, which passes through the oil tank, pierced in the middle (see the yellow arrow). On top are the two entries (purple arrows) through which compressed and cooled air (after passing through the intercooler) enters the air box.
One can also see one of the two direct injection pumps (red arrow). Driven by cam shafts, these pumps (one for each cylinder bank) deliver 500bar of pressure to the injector.

There are also three-phase cables (orange, as on all other engines) that transfer the AC power to the control box: it converts electricity to direct current so that the battery can store it. The green cable connects the MGU-H to the control unit, which is connected to the MGU-K by the blue cable.

COMPACT
Seen from behind, the Japanese six-cylinder shows the air box (yellow arrow), the two pipes of the wastegate (blue arrows), the turbine (red arrow) and the clutch, here hidden by a black cover (green arrow).

On the Honda block, the clutch is mounted on the thermal block rather than on the gearbox. The relatively low engine speed of the turbo V6 (limited to 15,000rpm) makes it possible to attach the clutch to the engine, a solution already seen in the past and preferable in view of the significant increase in torque compared to the previous atmospheric V8. This configuration is identical to the one used by Mercedes.

WORK IN PROGRESS
At Suzuka, we also got a good look at the battery of the Japanese V6 which seems very compact, especially compared to the system fitted to the Ferrari SF71H.

After the second specification, which appeared in Montreal, Honda introduced in Sochi the third and last evolution of its RA618H block. Although more powerful, this version posed driving problems to both drivers, the torque sometimes being delivered unpredictably. That's why Gasly and Hartley had to go back to the previous specification in qualifying and in the race in Russia.

To remedy this, Honda dyno-tested last week an optimized mapping, which improved the torque delivery and, therefore, mitigated the strong oscillations generated in the gearbox.

However, the problem doesn’t seem completely solved, with Gasly claiming to have encountered "serious oscillations when upshifting [during free practice on Saturday], [forcing him] to adopt a fairly conservative mode of exploitation". To solve it, at least partially, Honda obtained from the FIA an exemption regarding Parc Fermé rules to make an overnight change on Saturday evening. For some reason however, the FIA had a change of heart and instructed Toro Rosso, on the grid, to revert to its previous settings.

Whatever the case, the increase in power is real and has undoubtedly contributed to the good qualifying pace of the STR13 (with Hartley lining up P6 and Gasly P7): “From the performance point of view, we are happy. The post-shift oscillations, maybe some torque delivery at low-RPM, we will assess the data from here and can improve for the next race,” explained Honda technical director Toyoharu Tanabe.

Certainly, the reliability of the powertrain is not yet optimised, and its power is perhaps now only at the level of that of the Renault engine. Nevertheless, since partnering with Toro Rosso, Japanese engineers can work and make progress in a calmer environment, and can draw the lessons from possible mistakes in a better way.