Van biến thiên là cái gì? VTEC Turbo mà lại không phải là VTEC? | Đường 2 Chiều

Hello everyone, welcome back to H2O. Honda has VTEC, which is Vant Vientiane. Toyota has VVTi, which is Vant Vientiane. BMW has ShiftCam, which is Vant Vientiane. Yamaha has VVA, which is Vant Vientiane. So, what is Vant Vientiane? Are they the same or different? Let's get started. In the previous episode, I have talked about Vant Vientiane. Vant Vientiane is controlled by ShiftCam. The opening time depends on ShiftCam. Let's talk about what will happen if the RPM is too high. There is a problem with a basic ShiftCam. If the RPM is too high, the valve will close and open too fast. If the RPM is too fast, the engine will not have enough air and fuel. This will cause the engine to lose a lot of power. To solve this problem, there is a solution. We have to change the opening time of the valve to ensure the amount of air in the combustion chamber. The simplest way is to change the opening time. We will open the valve earlier and close the combustion chamber later. There is a period when both the valve and the combustion chamber are opened at the same time. This period is called overlap. According to the theory, this overlap should be increased along the tour. The higher the RPM, the longer the overlap period. In addition, this overlap period will cause a phenomenon called scavenging in the combustion chamber. In Vietnamese, it means cleaning up the trash. In this period, the new air flow into the combustion chamber will clean up the engine and push all the exhaust gas back inside. If the overlap period is too short or even zero, it will only work well in low tour. However, when the RPM is high, there will be a phenomenon of lack of combustion. This will cause a reduction in fuel consumption and affect performance. Conversely, if the overlap period is too long, it will only work well in high tour. In low tour, the air will be sucked in by the exhaust gas. It will be pushed out because the opening time is too long. This is when VanBienThien technology starts to work. The name VanBienThien probably refers to its function. It is the valve system that the opening time will be changed flexibly according to the number of rounds in the engine to optimize the engine. The simple meaning is that VanBienThien will help the engine achieve better performance in wider tour. However, behind the name VanBienThien, there are different technologies and methods. As well as its performance will not be the same. We will go through the most basic VanBienThien technologies on the market now. The first technology I want to introduce to you is Cam Phasing. Cam Phasing is a technology that has a cam shaft but does not connect to the cam head. It can change the angle of the cam shaft. This will help control the opening time of the valve. It can be earlier or later. It will change the angle of the cam shaft to change the opening time of the valve. Basically, this system will increase the overlapping period in the higher rounds. That is, it will not be pushed into the exhaust gas. The advantage of this technology is that it is very simple. It has a low production cost and is lighter than other valve technologies. One more thing is that this technology will have a cam shaft that can be phased continuously. This will improve the torque better in a certain tour. However, this system can only change the opening time of the valve. It cannot change the time and the opening degree of the valve. Therefore, the power of this valve system in the exhaust will be better than the second type of cam, which is cam changing. Some of the cam phasing systems that we are familiar with on the market now. For example, Toyota has VVT-i, which is a cam phasing system. In the past, on the BMW E46, we had the VANOS system. On the Honda, we have VTC. This is VTC, not VTEC. VTC only controls the opening time of the valve. It does not interfere with the opening degree of the valve. It is not VTEC. I will share VTEC right after this. The second type of system is cam changing. Unlike cam phasing, cam changing has a different operating structure. This system will include more than one cam. It will be activated in different touring circuits. It will be read by the ECU of the car. Depending on the touring circuit, each type of cam will be activated. The most typical example of this system is Honda VTEC, a very famous technology. Honda is one of the leading car manufacturers in this technology. With a car with two different cam sizes, the lower cam will be activated on the camshaft. Of course, with a lower cam, the opening degree of the valve will be smaller. In low touring circuits, the engine does not need much air. Therefore, the opening degree of the small valve will increase the pressure. Increasing the pressure, the speed of the air entering the combustion chamber will be faster. This will help the combination between gasoline and wind to be more effective. As well as fuel consumption in the combustion chamber will be more effective. However, in high touring circuits, the engine needs more air. The more air, the more power and horsepower the engine will produce. Therefore, at that time, the higher cam will be activated. As you can see in the figure, in high touring circuits at high RPM, a switch will be activated by the water. This power will be controlled by the ECU. When it is recognized by the depth of the foot of the bike, the speed and the RPM, it will be activated by locking the moving camshafts together. And the higher camshaft will activate a camshaft. At the same time, pushing the other camshafts, the higher camshaft will help push the valve down deeper, open wider and open longer. And the engine will be able to load more gasoline and wind. In addition, the cam changing system has 3 different types of camshafts. For example, on a bike with a 4-cylinder 16-valve engine, at low touring circuits, it will use one camshaft. At mid-touring circuits, it will use another camshaft. And at high touring circuits, it will also use another camshaft. The special feature of these 3 different types of camshafts is that at low touring circuits, the 16-valve engine will use only one camshaft instead of both camshafts. And the bike will become a 12-valve engine. And until it is converted to a camshaft for mid-touring and high touring circuits, it can use all 16 valves. Its operating principle is basically the same. But these 3 different types of camshafts will help the bike save more fuel at low touring circuits, as well as reduce the amount of gas released into the environment. In addition, with the camshaft type that uses many camshafts of different sizes, each type of bike will have its own technology and operating methods. Another example is the shift cam system of BMW, which they put on their motorcycles such as the R1250GS, a boxer bike, or the S1000RR. Instead of using many rocker arms and then using bolts to lock them together, the BMW manufacturer uses a camshaft that can move, and they will replace each other with different camshafts to act on a fixed rocker arm. This is also an example for you to see that different brands of bikes will have their own research and their own operating methods for their own technology. The camshaft system has the advantage of improving the strength of high touring circuits. However, the structure is quite complicated and does not work continuously like a camshaft. This will not help the engine achieve a good torque in a touring circuit like a camshaft. So what if we combine these two technologies together? Of course, the manufacturers have already thought about it. In Toyota, we have VVT-Li, not VVT-i, but VVT-Li. In Honda, we have i-VTEC. In BMW, we have Valvetronic, and so on. There are many technologies of different brands with different names. With the cam systems that are combined between cam phasing and cam changing, the structure will definitely be extremely complicated. However, this combination will have the characteristics of both types. We will have continuous changes, continuously changing the timing of opening the valve, as well as achieving a good torque in a touring circuit, while still having good power when operating at high speed in large touring circuits. And then there will be some fun facts that you can find on the Internet. First of all, the VVT-Li engine of Toyota, the engine that I just shared with you, is almost no longer in use because it does not meet the Aero 4 emission standards. A second fun fact is the Civic Type R, the most sporty version of the Civic series. It will only use the i-VTEC camshaft on the camshaft, not the camshaft. The reason is that the car already uses a turbo, so if we expand the camshaft, it will be able to absorb the air into the turbo more effectively, and will help push the camshaft to absorb the air more effectively. A third fun fact is the 1.5 VTEC turbo engine of Honda Vietnam, which is installed on Honda vehicles in Vietnam. In fact, it is not VTEC, but Dual VTC. Basically, it works like Dual VVTi, that is, there will be a camshaft on both the camshaft and the camshaft, the camshaft and the camshaft, but it does not have the technology to use a lot of camshafts and change the opening degree of the camshaft like VTEC. It is VTEC turbo, but it is actually Dual VTC, it is not VTEC. The fourth fun fact is that Honda also puts this camshaft technology on their vehicles, for example, the CB400 or the VFR800. The fifth fun fact is that VTEC is actually a meme, and this meme is very popular with motorcyclists in the US. The sixth fun fact is the VVA transmission system on Yamaha's 155-cylinder vehicles. It uses two different camshafts to change, it's like VTEC, but of course it's just like VTEC, it's not VTEC. Its operating principle is cam-changing, however, this will help improve the weaknesses of the RoHC engine when we use the car in high-rev solutions. A weakness of the RoHC engine that Yamaha now believes they can improve, and this engine is expected to be on the Yamaha Excelter 155 to be compared with the Winner. But this is not the Winner comparison with Yamaha, guys. And the last fun fact in today's lesson is Toyota's 2ZZ-GE engine. The engine that uses the VVT-LI camshaft system is designed by Yamaha based on Toyota's previous ZZ engine platform. And Yamaha, after working on this engine, has improved and improved a lot of engine performance. And this is one of the most famous and best Toyota engines ever produced. Although it is no longer available now, but in the past, this engine was also purchased by Lotus, a British car manufacturer, and installed on Lotus Elise or Lotus E-Cigar, which are very famous cars. So Lotus used this engine to bring that line of their cars. And the last thing is my very basic sharing, due to the time limit, I will only share such basic things about the camshaft system. And I hope that through this lesson, you will understand more about the camshaft system that is equipped on the cars and how it is different. After this lesson, what do you think is the next technical topic of 2M? Please comment below for us to know. Thank you for watching. Please like, share and subscribe to support 2M. We will continue to study and improve the content to produce better products. Goodbye for now.