Can you be an enemy of the world again? Brief Comment on Mazda SKYACTIV-X Second Generation Chuangchi Blue Sky Engine Technology

At the 2017 Mazda Global Technology Forum at the end of August, Mazda finally unveiled the mystery of SKYACTIV-X, which is different from the previous PPT. This is a real test machine. This NB’s technical exchange meeting like the Global Summit Forum only invited four domestic media, and I am one of them…

Keke, okay, it seems that everyone in this X suit does not believe. In this case, we will use the text and image data of the invited media to analyze the surface of the mysterious SKYACTIV-X engine from Mazda as much as possible to see what new technology it uses, what it can bring to us. .


The following pictures are from the car home, invaded.

First of all, its appearance looks like this:

Come, change your posture

In the following, the following is generally seen from the layout of the engine and the distribution of parts:

A. The 4-2-1 exhaust manifold equipment was removed;

B. Adopting a supercharged air intake mechanism, the Mazda tube is called a fast response air supply unit;

C. The large-capacity aspirating intercooled EGR valve is matched to the high-efficiency EGR cooler. The quick-response EGR solenoid valve is used without accident. Don’t ask me how to know. Take a look at Toyota’s Dynamic Force Engine. (That is the 8th generation Camry new 2.5 engine, the engine that claims to be the most global thermal efficiency)

D. Dual electronically controlled variable valve timing (VTC), this is the latest product of Denso, even the Dynamic Force Engine is only used on the intake side, but don’t forget, SKYACTIV-X officially claims to be 19 years old. When it went public, Toyota said that it could not be used.


From the appearance of the shape, we can get these four conclusions. Now let’s talk one by one:

A. Regarding the cancellation of 4-2-1 exhaust manifold equipment, the role of 4-2-1 exhaust can be known, summed up two points:

1. Reduce the scavenging insufficiency caused by the interference of the adjacent cylinder exhaust, and the exhaust resistance is too large;

2. Cooperate with the inlet and outlet valve overlap angles, which is beneficial to the engine to achieve high compression ratio and reduce the chance of knocking.

It sounds like this 4-2-1 exhaust manifold is a tool for Mazda’s brush compression ratio. Why do you want to cancel it?

The key reasons are related to policy and environmental protection. You can recall the pre-launch time of this machine: 2019 (domestic at least after 2020), the implementation of the national 6a environmental protection regulations in 2020, Mazda just rushed ~ 4-2-1 exhaust Due to the long pipeline, the manifold could not reach the environmental appeal of the three-way catalytic converter as soon as possible, so it had to give up.

PS: The owners of the current Mazda should all enjoy the title of “base tract tractor”. The reason is that the 3-2-1 exhaust manifold pipe is long, causing the three-way catalytic converter to heat up slowly. Mazda has to idle the rpm. Increased by the rapid warm-up (quick access to the normal operating temperature of the three-way catalytic converter).

Oddly enough, the Mazda test machine does not use the cylinder head exhaust manifold integration technology. Is there a way to optimize the emissions, the 4-2-1 exhaust manifold will reappear on the SKYACTIV-X? We still have to wait and see.

High energy ahead, new technology popularization –

The above describes the 4-2-1 exhaust manifold technology. A little understanding of the mainframe’s packages is more important to understand the current built-in exhaust manifold technology (4-1 exhaust). The advantage of this technology is precisely the shortcoming of the 4-2-1 exhaust manifold technology. Since the first requirement of the manufacturer to develop the engine is environmental protection (the energy saving power is also strong enough to comply with laws and regulations before it can be marketed), so it is now popular. Its 3D model is as follows:

Seeing that the structure should be understood as environmentally friendly, close to the three-way catalytic converter, this equipment has a benefit, which can significantly reduce the width of the engine assembly, and the depth of the cabin squeeze passenger compartment will become smaller, which is beneficial to Space improvement (Mazda is lying again).

The problem is, is there a solution that is compatible with the advantages of these two designs? Clever children’s shoes say that I don’t have to integrate the 4-2-1 exhaust manifold in the cylinder head – Bingo~ This is our latest exhaust technology, the cylinder head has a built-in 4-2 exhaust manifold. The 3D model is roughly as follows:

So is there a manufacturer that actually uses this technology? Please take a look at the picture above – from the car home technical article “you still have to talk about the Land Rover Ingenium engine”, this 2.0T is also Land Rover’s latest self-developed engine (made in the Chery Land Rover Jaguar factory), it can be clearly seen The cylinder head has a built-in 4-2 exhaust manifold.

Why is the current technology not widely used? The reason is very simple. The biotechnology (see the author’s last article for the meaning of this term) is too difficult to process. The more pipes are integrated in the cylinder head, the stricter the requirements on the level of casting processing, especially the cylinder head of the small displacement engine. Very (smaller).
Eggs: Honda adopted this technology for the first time in the next heavyweight model.

B. SKYACTIV-X uses supercharger technology. To be honest, at first I thought it was the adaptation of electric turbine technology, but after thinking about it, the electric turbine must be used with 48V light mixing. Mazda will not even use it. The current costly solution is applied to the Mazda3 class (according to the roadside agency, the Mazda6 will be replaced by a rear drive, while the SKYACTIV-X is equipped with electric turbine technology and 48V light mix). What I want to say is that this is actually the most sensible choice for SKYACTIV-X.

Why is it the most sensible choice?

SKYACTIV-X pursues an ultra-high air-fuel ratio (A/F) under compression ignition conditions, which makes the engine achieve lean combustion that is difficult to achieve with gasoline engines, saving a lot of fuel (the power increase is less obvious). The method of increasing the mass of the intake air per unit time can only be pressurized under the fixed cylinder volume. Mazda also simply abandoned the natural air intake mode and selected the booster. Everyone knows that the current mainstream supercharging methods are turbocharged and supercharged. Due to the existence of turbo lag and the limitation of low compression ratio, turbocharging is a supercharging method that has been despised by Mazda. However, the supercharger is also defective. It will take up part of the engine power during operation. Therefore, it has been widely used on large-displacement engines. The two are relatively light, and Mazda finally chose supercharger.

Did you see the supercharger connected to the engine crankshaft with a belt?

As for electric turbines, they have the same advantages, no turbo lag, low moment of inertia, and no engine power. Disadvantages – not expensive, but also equipped with a 48V light-mix system monopolized by European suppliers.

The above analysis of the advantages and disadvantages of the three supercharging methods shows that the electric turbine is the optimal intake boosting scheme of SKYACTIV-X.

C. The large-capacity aspirating intercooled EGR valve is matched to the high-efficiency EGR cooler, and a fast-responding EGR solenoid valve is used without accident.

What are the consequences of high air-fuel ratio combustion? Rich air generates a lot of nitrogen oxides (NOx), which is a headache problem, so the above equipment is also an inevitable condition.

I have a lot of online spectators claiming that the Toyota Dynamic Force Engine has reached the world’s NO.1 maximum thermal efficiency. It is completely contrary to the argument of Mazda technology. At present, the solution that SKYACTIV-X can meet environmental protection requirements is entirely based on Toyota. Besides, the main technical points that the Dynamic Force Engine can achieve such high thermal efficiency are two points:

1. Rapid combustion (the design point for rapid combustion is high-rolling air intake), and high compression ratio is also based on this point.

2. Fast-responding EGR system These two points are also the technical points that Mazda has never used in production cars.

Someone once asked me why Honda’s 1.5T can be the leader in thermal efficiency in today’s turbocharged engines (38%), thanks to the fast combustion technology of high-roll inlets.

D. As for the dual electronically controlled variable valve timing (VTC-E), there is nothing special to say, specifically changing from mechanical oil pressure control to electronic control, making the VTC’s response faster and more timely, optimizing the engine’s breathing. Of course, this is also one of the effective means to increase the compression ratio of the engine.

The above is the in-depth analysis of the distribution of the appearance parts of the SKYACTIV-X engine released by Mazda. After all, Mazda is still under development, and the engine is likely to have some changes. I am not responsible for the difference with the final product. .

tail:

The characteristics of this engine’s visual inspection are generally finished. In fact, there are still a few points worthy of interest. Just talk about it:

1. High-pressure injection system up to 1000 bar or above. As far as I know, Bosch has this type of high-pressure injection system. It is not clear whether to use its development products;
2. The new engine will be more “pick-up” than the current model. With a low-grade fuel, the compression system will stop working and the entire engine will change back to a single spark plug. Look at the development site of Mazda’s current SKYACTIV-X. If this is not optimized and improved during mass production, the domestic two barrels of oil will make him an ordinary gasoline engine. The consequences can be imagined (of course, there are people who add 98RON , considering its positioning, after all, does not meet the consumption habits of Chinese people);
3. With a more complex oil and gas separation system, the compression ignition condition is definitely a great gain for the crankcase gas. If the oil and gas separation system is not redesigned, the SKYACTIV-X is likely to become another engine oil. Gasoline blender.

4. I reserved the expansion of the hybrid system. This is the most gratifying place for me to read the complete article. Regardless of the analysis of the engine surface or the final experience of the invited media, I am not really developing the current development of SKYACTIV-X. Satisfied, the technical stacking did not achieve its due effect, and the biggest change point came from the mix with the hybrid.

Conclusion: I am not optimistic about the Mazda SKYACTIV-X alone, but I am looking forward to the chemical reaction with the Toyota THS hybrid system or the 48V light mixing system. Mazdajun should continue to work hard.

I look forward to your attention to the column and the two authors. If you have any questions, please feel free to contact us.

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