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Valve device is a part of valve-train engine play a very important role in engine working. Fuel engine work done by the intake, compression, power and exhaust of four working process. To make the engine run continuously will have to make the working process of the four cycles, the order cycle to work regularly. The working process of the two of them, intake and exhaust process, need to rely on engine accurately valve-train mixture, according to the work order of each cylinder conveying and combustion of exhaust fumes. The other two working process, compression and work process, you must isolate the cylinder combustion chamber inlet and exhaust passage with the outside world, don't let the gas leaked to guarantee the normal work of the engine. Responsible for the part of the work of valve-train is valve. It is like a human respiratory organs, breathe in breathe out, and short of it.
With the development of technology, the speed of the car engine is more and more high, the modern car engine speed generally can reach more than 5500 revolutions per minute, complete the working process of the four just 0.005 seconds, the traditional two valve have not qualified for working in such a short time to complete ventilation, restricting the improvement of the performance of the engine. Solution to this problem is to expand the size of the gas in and out. In other words, is to use space for time. More valve technology is one of the best ways to solve the problem, until the 80 s more than promotion valve technology to make the overall quality of the engine had a qualitative leap. Many valve is to point to each cylinder of engine valve number more than two, the two inlet valve and a three of the exhaust valve valve type; The two inlet valve and exhaust valve 4 valve type; Three two exhaust inlet valve and gate valve type.
At present, a lot of cars on the valve engine is four more of the valve type. Four cylinder engine has 16 valve, 24 on 6 cylinder engine valve, eight cylinder engine has 32 valve. Such as Japan lexus LS400 saloon car engine is 32 8 cylinder valve. Increased the number of the valve to increase the corresponding distribution mechanism, structure is complex, generally by two overhead camshaft type control is arranged in the cylinder combustion chamber on either side of the center line of valve. Valve arranged in the center of the cylinder combustion chamber on both sides of the tilted position, is to enlarge the diameter of valve head, as far as increasing air flow through the area, improve ventilation performance, form a compact version of the spark plug is located in the central chamber, is conducive to rapid burning of mixture.
Someone ask, since the valve, why not see a more than six cylinder valve engine? Thermodynamics has a concept called "blind area", refers to the garden of valve weeks multiplied by the lift of the valve, the valve open space. "Blind area", the greater the description of the valve open space is larger, the greater the air inflow. Audi 100 saloon car engine, for example, its four valve "blind area" value than two valve "blind area", in the state of air intake to big half, seventy percent larger in the state of exhaust. , of course, every thing has its certain scope of application, the more is not to say that the valve "blind area" the greater the value, according to experts calculate when each of the cylinder valve increases to six, "blind area" value will be decreased, and the more complex the valve the mechanism, the greater the cost. Therefore, at present, a lot of car fuel engine valve of each number of the cylinder valve is three to five, with four valve and among them the most common.
Valve engine for gasoline engine as an example, compared with the traditional two engines, the former can take in more air, work is to mix the fuel combustion, saving fuel, faster discharge waste gas, low emission pollution, can improve the power of the engine and reduce noise, conforms to the optimization of environment and the development direction of saving energy, so much valve technology can quickly popularized.
More than the valve fuel engine began to rise, some people think that it is not a technical flaws in a low speed smooth, well-known German porsche car company will hold such a view. With the continuous improvement on the technology, the technical defects of the valve of gas engine and overcome step by step. Porsche cars in recent years, the company's 944 s2 cars packed with four cylinder four valve engine, now, the world more than almost all senior cars equipped with valve fuel engine.
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