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[YesAuto New Technology Interpretation] Recently, Japanese manufacturers such as Toyota, Honda, and Mazda have frequently released new technologies related to improving engine fuel efficiency. Now, overseas media has revealed that BMW is also testing a technology that can increase engine power while reducing fuel consumption. So, is this technology called spray cooling a bit of an exaggeration to improve the engine?

■ How does it work?

In fact, to some extent, cars are quite similar to humans, and the role of the engine is similar to the human heart. When we breathe normally, we just need to inhale air from our nasal cavity. When running long distances, the nose and mouth need to work together. A similar principle is applied to adjust the valve mechanism of the intake and exhaust systems according to the different working conditions of the engine. When the turbocharged engine is working under high load, it will gradually inhale hot air with higher temperature and lower density, which brings the disadvantage of lower combustion efficiency. BMW's technology is to reduce the temperature of the sucked air at this time and improve the combustion efficiency.

When the system judges that the engine is working under high load and high working conditions, if only opening the spray system in the intake manifold fails to effectively reduce the intake air temperature, the nozzles arranged in the combustion chamber will also be opened to spray water mist directly. Into the combustion chamber, thereby cooling the engine more effectively.

■ Water must be the enemy of engines?

As we all know, when a vehicle is driving over a water-filled road, we must pay attention to the depth of the water to prevent it from pouring into the engine from the intake port and through the intake manifold, causing damage. So, wouldn't the technology of actively “spraying water” into the combustion chamber of the engine damage the engine?

In fact, our previous “carefulness” does not conflict with this technology. The key to the problem lies in the amount of water, that is, the control of spray in this technology is the top priority. The computer will accurately calculate the mixing ratio of water mist, gasoline, and air before spraying to ensure that the mist can not only fully absorb heat, but also evaporate before the mixture enters the combustion chamber and is ignited to avoid affecting the combustion efficiency. At the same time, in order to avoid the phenomenon of insufficient combustion caused by spray when the engine is working at low load, the spray nozzle in the combustion chamber does not work at this time.

■ Not only helps the engine to be more stable

Thanks to this technology, the engine compression ratio can also be increased from the original 9.5:1 to 11:1, the output power can be increased by up to 10%, and the reduction in the intake air temperature brought by the spray system can also reduce the heat of the engine-related parts. load. BMW’s official information shows that the service life of the engine’s pistons, valves, catalytic converters and turbochargers will be greatly enhanced. In addition, the fuel compatibility will also be better. Therefore, even if the gasoline grade of some countries is lower than that of Germany, the design power can be achieved without reducing the engine output due to fuel quality problems in individual regions. .

Related videos:

Just looking at the text is a bit boring. The following video shows the system from not working when the engine load is small to intervention work when the load is high. It is recommended that you watch it.

■ Problems that may be encountered by new technologies

● Control the amount of spray

Although this spray system has many advantages such as increasing engine power, improving engine fuel availability, improving the durability of related components, and reducing fuel consumption, there are many technical problems that need to be overcome.

● Selection of water source

Although this spray cooling system is designed to exclude most of the vehicle environment under extreme weather conditions, that is to say, you do not need to consider replenishing water for the spray system in most cases of daily driving, but if it is more like in winter, In a dry environment, you may need to add spray water to the system.

■ New technology with a long history

Similar to the new technology that is gradually applied to automobiles such as the same line transfer, this spray cooling technology was first applied in the aviation field. With the continuous maturity of the technology, automobile manufacturers such as the United States and Europe used it for volume in the middle of the last century. Production cars, but with the further development of technology, the birth of the intercooler eventually replaced the spray cooling system.

Since then, with the development of technology, the intercooler was born to replace the spray cooling system, but it is still in service in modified cars and racing cars. More than half a century later, BMW “turned out” this technology again. The BMW M4 safety car for the 2015 MOTO GP Grand Prix is already equipped with this technology. Obviously, the harsh track is the best test bed to test the stability of this technology, and it is a field survey of its mass production situation when it is mounted on the 1 series.

From the M4 safety car to the future 1 series, it reflects the different design ideas of BMW. For the M4 as a safety car, it needs to work under high working conditions and high loads for a long time. In addition to improving its power performance, the spray system can also reduce the increase in engine stability brought about by the intake air temperature.

On the other hand, the spray cooling system used in the 1.5T engine on the 1 Series comes from the condensate of the air conditioning system. This means that only when you turn on the cold air, will the spray cooling system provide cooling water. From this point of view, BMW will refer to the outside temperature in terms of logic control of this spray cooling system.

■ The future of new technology

At present, the 2 series sports wagon and i8 are equipped with a 1.5T engine code-named B38. The recently modified BMW 1 series has also added a 1.5T engine power configuration. I believe that when the spray technology matures in the future, we This technology will be seen in more and more BMW models.

Full text summary:

Nearly half a century ago, technology has surfaced again. This phenomenon is not a retrogression of technology. The spray cooling system will play a role in assisting the intercooler to reduce the temperature of the intake air when the direct injection technology and turbocharging technology are in power today. For performance cars, it can bring an increase in engine power. For family cars, the fuel-saving effect it brings will also be favored by consumers.

Related links:

New fuel-saving tool? Comment on Toyota's 1.5L Efficient Engine
http://www.autohome.com.cn/tech/201506/875009.html