Plastic intake manifold is located between the throttle and the engine intake valve, called the manifold, because the air into the throttle, after the manifold buffer system, the air runner in this divergence, the corresponding engine cylinder The number of four-cylinder engine, such as four, five-cylinder engine has five, the air were introduced into the cylinder. For airway fuel injection engines or diesel engines, the intake manifold only distributes clean air to the cylinder inlet. The intake manifold must distribute the air, fuel mixture or clean air evenly to each cylinder as much as possible so that the length of the gas flow path in the intake manifold should be as equal as possible. In order to reduce the gas flow resistance, improve the intake capacity, intake manifold wall should be smooth.
The intake manifold is located between the throttle and the engine intake valve, called "manifold", because the air into the throttle, after the manifold buffer system, the air runner in this "divergence" Corresponding to the number of engine cylinders, such as four-cylinder engine there are four, five-cylinder engine has five, the air were introduced into the cylinder. In the case of a natural intake engine, since the intake manifold is located behind the throttle valve, when the engine throttle is small, the cylinder can not absorb enough air, causing a high degree of manifold vacuum; and when the engine throttle is opened When the degree is large, the degree of vacuum in the intake manifold becomes smaller. Therefore, the jet fuel supply engine will be installed in the intake manifold a pressure gauge, the ECU to determine the engine load, and give the right amount of fuel injection.
Manifold vacuum can be used not only to provide pressure signals to determine the engine load, there are many uses it! Such as the brake also need to use the engine to help vacuum, so when the engine brake brake will be launched after a lot of light, because there is a vacuum-assisted reason. There are some forms of constant speed control that will also use manifold vacuum. And these vacuum tube once the leak or improper modification, will cause the engine control disorders, will also affect the brake action, so advise readers to try not to improper modification of the vacuum tube to maintain traffic safety.
The design of the intake manifold is also very knowledgeable, in order to engine each cylinder combustion conditions are the same, each cylinder manifold length and curvature should be the same as possible. As the engine is completed by four strokes to run the program, so the engine each cylinder will pulse into the air, based on experience, longer manifold for low speed operation, while the shorter manifold is suitable for high speed operation. So some models will use variable length intake manifold, or continuous variable length intake manifold, so that the engine in the speed domain can play a better performance.