Interpretation of Honda's "Earth Dream" core technology

    At the "2013 Honda China Media Conference" on June 14, Honda finally released its new generation of powertrain technology Earth Dreams Technology (hereinafter referred to as "Earth Dreams") in China. The reason why I say "finally" has two meanings. One is that this technology was released in Japan as early as 2011. The other meaning is that Honda, which has relied on VTEC for many years, has "finally" made a major leap in powertrain technology. These two "finally" determine the importance of "Earth Dreams".

    Cheyun will launch a series of topics on "New Power Ace". Faced with the pressure of energy consumption and emissions, various manufacturers are working on power technology. Volkswagen has taken the lead through the "Golden Partner". Although it has been bumpy, the overall effect is obvious. Other manufacturers naturally dare not take it lightly and have brought out their own new skills. Honda's "Earth Dream" can be regarded as the opening chapter of this series.

The core of the regular version of Earth Dream: i-VTEC DOHC direct injection

    Soichiro Honda paid close attention to powertrain technology, which also left a mark of "emphasis on technology" for Honda in the past. Among them, the core is naturally VTEC. Unlike ordinary VVT, the core of VTEC is variable valve lift, not ordinary timing. The variable valve lift has a much stronger effect on adjusting the working conditions of the engine than ordinary VVT. With it, the engine can greatly increase the power while taking into account the low-speed torque. Therefore, for a long time, Honda engines with the same displacement have greater power than others.

    This technology was applied to Honda's models as early as the 1980s, and quickly became popular throughout the series. Even now, this technology is still regarded as "high-end technology" by many manufacturers and only provided to high-end models. For example, Volkswagen does not have the same 2.0T engine as Audi (variable valve stroke, the same below), Peugeot does not have the 1.6T jointly developed by MINI, Nissan's VQ engine VQ25 does not have VQ37, and so on.

    VTEC is undoubtedly worthy of recognition, but sadly, Honda has become conservative and stagnant in the following two decades. An important example is that VTEC has a major innovation, namely the launch of the DOHC version. Unfortunately, Honda has not popularized this technology - currently only the 2.4L engine is DOHC. The difference between DOHC and SOHC versions is not just a matter of the number of camshafts, it directly involves whether the engine can achieve continuous adjustment of valve timing while achieving adjustable valve lift (SOHC is difficult to achieve this).

    Since VTEC is indeed very powerful, Honda will not fall behind even if it continues to rely on its old advantages. However, with the emergence of new technologies in recent years, Honda's advantage in power is no longer obvious. "Earth Dream" can actually be seen as a breakthrough and explosion in power technology for Honda after years of silence.

    Many people think that Earth Dream is nothing new, and it is nothing more than "following the trend" and adopting direct injection. Indeed, direct injection is the focus of this new power change, but it is not accurate to think that Earth Dream just has more direct injection.

    First of all, this series of engines is a new design, not an improvement on the original powertrain. This is very important, and it involves all aspects of the engine, including the so-called new piston coating technology promoted by Honda, low-tension piston rings, etc. This redesign is like a model change and platform change, which will bring a difference in power quality from the past.

    Secondly, the combination of direct injection and i-VTEC would be more ideal in theory. The purpose of direct injection is to improve the accuracy of injection, thereby improving efficiency, but the oil-gas mixture of direct injection is a problem. Variable valve stroke can allow the intake process to obtain more swirl at low speeds, which is obviously more helpful for oil-gas mixing. Honda's engineers certainly know this, but the reason why they have not adopted it before is that the advantages of VTEC still exist and they feel it is unnecessary, and secondly, the previous use of vertical direct injection affected the overall cost control. The new side-mounted direct injection solves this problem. At present, in China, conventional brands have both direct injection and variable valve stroke, and Honda is the only one.

    The third point is the popularity of DOHC. In the previous platform, Honda may have encountered cost or other problems when developing DOHC. This time, with the launch of "Earth Dream", Honda finally adopted DOHC for all its four-cylinder versions. It is possible that Honda has found a way to control costs, or it may be due to market pressure. In any case, this is indeed a big step forward.

The core of the regular version of Earth Dream: CVT

    CVT itself is nothing new. It is not popular because of its new technology, but because it is controversial. But it cannot be underestimated for Honda's "Earth Dream".

    Honda has a characteristic since its founding: it likes to develop and produce everything by itself. Honda believes that this can better control costs and ensure quality. This practice has won Honda a good reputation for a long time, but it has also become a hindrance to technological progress to some extent.

    For example, Honda has always used a parallel shaft transmission of its own design. This transmission has a different structure from conventional AT, so it cannot achieve common progress with conventional AT. In recent years, thanks to the improvement of technology of some transmission suppliers, the number of gears of conventional AT transmissions has increased and the performance has improved. Honda's parallel shaft transmission is constrained by its structure, and it is difficult to launch a version with more than 7 speeds while controlling the volume. Honda once thought of purchasing from suppliers such as ZF and Aisin like other manufacturers, but years of operating habits made it reject this plan, and finally placed its bets on self-developed CVT.

    According to the current publicity, Honda has indeed invested a lot in CVT. In particular, many methods have been used to improve efficiency and ensure reliability, such as adjusting the distance between the axles, controlling the pressure of the tapered wheels, etc.

    CVT transmission is perfect in terms of performance, because it has countless gears. Not only 9AT cannot compare with it, but even 18AT cannot compare with it. In theory, it can make the most efficient use of engine conditions, achieving both power and fuel saving. The smoothness is also perfect.

    From the perspective of the structure itself, it is also helpful for improving power. The reason why it is not popular is reliability, and the impact of the protection program passively selected because of reliability on driving performance, etc. Before the actual test, it is difficult for us to draw a conclusion on the performance of Honda CVT in this regard. But if Honda's CVT really has a breakthrough in reliability, it can completely get rid of the constraints of the number of gears, and it is fully capable of competing with new transmissions such as 9AT and DSG.

summary:

    Judging from the information that has been released, Honda's "Earth Dream" has made a lot of noise. Honda obviously hopes that this innovation will make a comeback in the field of power technology and regain its previous leading position. It's just a pity that no supercharged version was launched this time, which is indeed Honda's shortcoming. However, there are reports that the supercharged version of Honda's new power platform is under development, which shows that Honda still has a backup plan.