Britain and finidi extend the mission of fuel engine: VC- turbine engine technology

It seems that in recent years, the internal combustion engine has become a "nail house" and a "sharp knife" for all competitors under the trend of electrification. Most traditional car companies are thinking about how to adapt to electrification more quickly, thus almost giving up the technical research and development of internal combustion engines, and more is to improve the thermal efficiency of engines to improve the running performance of hybrid vehicles. In fact, this is not wrong. Faced with increasingly stringent emission regulations, Britain and finidi seem to have no choice but to give the answer directly: VC Turbo.

First of all, we must know: VC-Turbo is a technology for engines, not engines.

Secondly, this is a brand-new engine technology, instead of Nissan, Britain and finidi copying the M274 engine and products of Mercedes-Benz.

Third, this is a high-power engine with the aim of high efficiency and environmental protection.

Variable compression turbocharging

Namely variable compression ratio turbine engine technology. By the way, the meaning of compression ratio here is simply the ratio of the volume of air compressed by the piston to the actual volume after entering the engine combustion chamber.

The variable compression ratio can make this ratio change under certain conditions. The advantage of this change is to improve the cycle thermal efficiency. Note that this is the cycle thermal efficiency. At present, the most representative is Mazda's blue sky technology, which is to adjust the closing time of the intake valve in the simplest way, and draw out a small part of the mixed gas in the cylinder during the compression stroke through the inertia principle of gas, thus reducing the compression ratio. However, the restriction condition is that the expansion ratio in the cylinder remains unchanged, so that less consumption can be realized.

Mazda's solution is to extend the exhaust path and advance high-density fuel injection to further burn the mixture, thus solving the problem of low torque. In addition, Chuangchi Blue Sky is not a simple engine technology, but the coordination and adjustment of a whole set of engines and transmission systems. In fact, Volkswagen EA888 has also achieved high compression ratio and high thermal efficiency, but it has not passed this technical approach.

So we also see the benefits of increasing the compression ratio. Of course, Nissan, Britain and finidi also know this matter, and put forward this concept very early. In 2002, we tried to produce engines with variable compression ratio. However, due to the limitation of materials and processing technology at that time, the strength of connecting rod was unstable, which led Nissan to temporarily give up the research and development of this technology and focus on improving the power output of the engine.

Many people also know that Saab, an automobile manufacturer that produces fighter planes, has been pursuing engine technology for more than 30 years. At one time, they also racked their brains on variable compression ratio, and at that time SVC was put forward. However, due to the complex structure of the engine, although it can also be changed to 8: 1 and 14: 1, the volume and weight of the engine cannot be controlled by the technical conditions of that year because the control part needs high-power driving motor for compensation control. At the same time, the internal intake and exhaust combined structure is too complicated, which is a great challenge to the maintenance of the engine. So these two problems have not been solved, which leads to the lack of this technology. However, according to the data at that time, with the help of mechanical turbine, 1.6L engine can provide 225 horsepower, and the fuel consumption per 100 kilometers is only 8.3L

The time has changed to 20 16. With the rapid development of processing industry, materials have also made great progress. Nissan also reconsidered how to effectively complete the free adjustment of compression ratio. Nissan engineers solved this problem with three key components: multi-link, motor and reduction gear.

Generally speaking, the crankshaft of a normal engine can be fixed and cannot move at will, so as to ensure the stable operation of the piston connecting rod. Engineers in Britain and finidi added a set of multi-link mechanism to the crankshaft connecting rod, and the multi-link mechanism was connected with the driving motor through the reduction gear. In this way, the control problem of the "century" is solved.

From the official drawing, we can see that the force of the motor can control the rotation of the reduction gear, and at the same time drive the relative angles of multiple connecting rods to change, thus controlling the stroke position of the piston on the crankshaft, thus completing the change of compression ratio. With the cooperation of EUC, the compression ratio can be accurately controlled.

It doesn't matter. The description may be too complicated. We can see it through this animation. On the far right is the motor-driven actuator (harmonic actuator). By adjusting the position of the control shaft through the transmission arm, the angle of the multi-connecting rod on the crankshaft changes, and the piston connecting rod also changes with the stroke, thus changing the stroke of the piston.

We already know the core things, but this is only the beginning, just to improve the thermal efficiency. You should know that this is the technology that accompanies the turbine engine. The turbine passively squeezes the engine, so it will produce a certain load relative to the engine. One of the inevitable disadvantages of many engines with high compression ratio is insufficient low torque. So Britain and finidi face another problem.

The most important thing to improve power is to improve combustion efficiency. At present, the two most popular methods are Atkinson cycle and Otto cycle. Thanks to the free conversion of compression ratio, under the condition of high compression ratio, the combustion mode can carry out Atkinson cycle, which requires the piston stroke of the engine to be longer, so that the expansion ratio can be greater than the compression ratio, and there can be a larger expansion volume during combustion, which can fully release heat, improve utilization ratio and achieve high efficiency; Similarly, with the reduction of compression ratio, the engine can return to the standard Otto cycle, so this perfectly solves the obstacle of power output.

Friends who understand the working principle of the engine should know that the engine will knock at high compression ratio. The main source of detonation is the physical phenomenon that fuel and oxygen in the air cannot be effectively mixed and burned. For Nissan finidi, it is much easier to overcome this difficulty, which brings us the famous VQ series engines.

Nissan aims to improve the fuel efficiency of VQ engine more effectively and tap the potential of the engine. In the early days, the electronic control system was added to realize the accurate control of combustion, so we can see the application of multi-hole injector in VR engine. It is not the 8-hole design of ordinary gasoline engine, but as many as 12 holes, just to make the atomization effect of fuel better. Using high-strength spark plug and turbocharging technology, the fuel burns quickly and fully, and with electronic control, the knocking phenomenon can be avoided.

In fact, these are minor problems, which basically depend on scientific and technological progress. This shows the agility of MPI and GDI injection methods in VC-Turbo engine. Overcoming a series of difficulties in high load and optimizing low load is also a concrete embodiment of the development and application of modern automobile industry.

Many people will talk about the running quality of a four-cylinder engine. Due to the inherent limitations, the crankshaft is destined to drive the piston connecting rod to rotate, so relative stress and inertia will inevitably occur in this process, which is also the biggest gap with V6, V8 and even more cylinder engines. Under VC-Turbo, the combined design of multiple connecting rods makes the piston connecting rod only need to do relatively vertical reciprocating motion without generating additional force angle, so the vibration is overcome and the running stability of the engine is significantly improved. So we can see that the operation of MR20 engine under VC-Turbo technology can be close to the stability of V6 engine.

Combining all the above technologies and features, we can see a complete VC-Turbo engine. Compared with the M275' s 2.0T engine, the fuel consumption increased by 35%, and even the four-wheel drive model increased by 30%. In terms of power, it can release 272 horsepower and 380n·m peak torque, which is much stronger than 21/kloc-0 horsepower and 350n·m of Mercedes-Benz M274. At the same time, the running smoothness is unparalleled.

At most, the development history of VC-Turbo has gone through more than 20 years, with more than 300 patented technologies. Nissan English finidi is not the kind of maker who is eager for success. No matter from the classic VQ series to the excellent VR series, even KR20 VC_Turbo has been honed bit by bit.

After talking about technology, let's talk about something practical. Although the engine is good, at present, only the QX50 is in use among the domestic models sold in Britain and finidi, mainly because the model is a platform with horizontal front drive, and there is little fundamental reason for the old QX50. Nissan's internal code is P7 1A, so it is essentially different from the previous generation in driving and riding.

In addition, the QX50 is equipped with Nissan's X-Tronic CVT gearbox, which is actually suspected of dragging its feet to some extent. Although the training is economical and smooth, compared with the previous 7AT, the shifting speed is much slower and the driving pleasure is much less.

There are also criticisms from Nissan's own problems. In order to maximize the benefits, it leads to the strategic mistakes of its brand. It has good technical advantages, but there is no way to adapt to the market. At the same time, Toyota and Honda, both Japanese, are trying to expand into hybrids, while Nissan is blocked at both ends; On the one hand, it was overjoyed in the field of pure electricity, and the accumulated experience was wasted, and it failed to put it on the market for the first time to win the opportunity; Secondly, in terms of mixing, technical barriers cannot be circumvented. Even in the field of optical mixing, it is only making a fuss about old technology, and there is no advantage at all. This series of reasons can also be seen in my previous articles, and you will have more understanding.

At present, Nissan's "failure" has also led to the fall of Britain and finidi, and the brand value has plummeted. A once good luxury brand has now become "Nissan Plus". I really don't know how long this fate will last, but judging from Nissan's new plan, it is also very pessimistic. Therefore, friends who like this brand should buy it and cherish it.

For articles about Nissan, those who are interested can browse the following articles:

Nissan has finally made a new move: Britain and finidi's "four-year plan" revival plan has officially become: Nissan Plus-infinitely approaching "Big Chery".