BMW engine spray cooling technology that takes into account both fuel saving and power

Recently, Japanese manufacturers such as Toyota, Honda, and Mazda have frequently released new technologies related to improving engine fuel efficiency. Now, overseas media have revealed that BMW is also testing a technology that can both increase engine power and reduce fuel consumption. So, is the improvement of the engine by this technology called spray cooling a bit exaggerated?

■ How does it work?

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

When the system determines that the engine is operating in a high-load, high-operating condition, if simply opening the spray system in the intake manifold still cannot effectively reduce the intake temperature, the nozzle arranged in the combustion chamber will also be opened to spray water mist directly into the combustion chamber, thereby more effectively cooling the engine.

■ Is water necessarily the engine’s nemesis?

As we all know, when a vehicle is driving on a flooded road, it is important to pay attention to the depth of the water to prevent it from flowing into the engine through the intake manifold and causing damage. So, won't this technology of actively "spraying water" into the engine combustion chamber damage the engine?

In fact, our previous "caution" does not conflict with this technology. The key to the problem lies in the amount of water, that is, the control of the 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 fully absorb heat and evaporate before the mixed gas enters the combustion chamber and is ignited, avoiding affecting the combustion efficiency. At the same time, in order to avoid the occurrence of incomplete 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 be increased from the original 9.5:1 to 11:1, and the output power can be increased by up to 10%. The lower intake temperature brought by the spray system can also reduce the heat load of engine-related parts. BMW's official data shows that the service life of engine pistons, valves, catalysts and turbochargers will be greatly enhanced. In addition, fuel compatibility will be better. Therefore, even if the gasoline grade of some countries is lower than that of Germany, the designed power can be achieved without reducing the engine output power due to fuel quality problems in some regions.

■ Problems that may be encountered with new technologies

● Control the spray volume

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

● Water source selection

Although this spray cooling system is designed to exclude most vehicle usage environments under extreme climate conditions, that is, in most cases of daily driving you do not need to consider refilling the spray system with water, but in a drier environment such as winter, you may need to refill the system with spray water.

■ New technology with a long history

Similar to new technologies such as steering by wire that are gradually being applied to automobiles, this spray cooling technology was also first used in the aviation field. As the technology continued to mature, automobile manufacturers in the United States, Europe and other countries used it in mass-produced cars in the middle of the last century. However, with the further development of technology, the birth of intercoolers eventually replaced the spray cooling system.

For BMW, the 1 Series test project with a 1.5T engine is not their first attempt. The BMW M4 safety car in the 2015 Moto GP Grand Prix was equipped with this technology. Obviously, the harsh racetrack is the best test bed to test the stability of this technology, and installing it on the 1 Series is a field inspection of its mass production.

From the M4 safety car to the future 1 Series, BMW's different design ideas are reflected. For the M4 as a safety car, it needs to work under high conditions and high loads for a long time. In addition to helping it improve its power performance, the spray system can also reduce the intake temperature to improve the engine stability.

On the other hand, the spray cooling system used by the 1.5T engine in the 1 Series uses condensed water from the air conditioning system. This means that cooling water is only provided to the spray cooling system when you turn on the cooling air. From this, it can be seen that BMW will refer to the outside temperature for the logic control of this spray cooling system.

■ The future of new technologies

At present, the 2 Series Sports Touring and i8 are both 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 this spray technology matures in the future, we will see this technology on more and more BMW models.

Summary of the full text:

The technology from nearly half a century ago has resurfaced, and this phenomenon is not a regression of technology. In today's world where direct injection technology and turbocharging technology are dominant, the spray cooling system will assist the intercooler in reducing the intake temperature. For performance cars, it can improve the engine power. For family cars, the fuel-saving effect it brings will also be favored by consumers.