Let's think about before it comes to the intake manifold, the air is entering the engine. The engine Introduction, we have referred to the operation of the piston within the cylinder, when the engine is in the intake stroke, the downward movement of the piston of the cylinder generated within the vacuum (that is, the pressure becomes small), and the outside air pressure difference is generated, so that the air can enter the cylinder. For example, we all should have been played pin also seen how the nurse syrup suction needle barrel! Imaginary the needle barrel is the engine, then when the the needle barrel of piston outward withdrawn, the syrup will be sucked needle barrel, while the engine is so air into the cylinder.
Composites began to become popular due to the relatively low temperature of the inlet end, the intake manifold material, lightweight internal smooth, can effectively reduce the resistance, increasing the efficiency of the intake air.
Well, back to the subject, the intake manifold is located between the throttle and the engine intake valve, is called a "manifold" is because air to enter the throttle buffer, after manifold system, air flow channel on "differences" in this, the number corresponding to the engine cylinder, four-cylinder engines have four, five-cylinder engine with five air were introduced into each cylinder. In a naturally aspirated engine, because the intake manifold located throttle, so when the engine throttle opening degree hrs, the cylinder can not be bothered by a sufficient amount of air, will result in the manifold vacuum is high; when the engine throttle opening degree, the degree of vacuum within the intake manifold becomes small. Therefore, injection fueling engine will be installed on the intake manifold a manometer, supply ECU determines that the engine load, while giving an appropriate amount of fuel injection.
Manifold vacuum not only can be used to supply the pressure signal determining engine load, there are many useful too! Such as brakes also need to use engine vacuum to assist, so when the engine brake pedal will light many, it is because of the vacuum-assisted sake. There are some forms of fixed speed control mechanism also use manifold vacuum. Once these vacuum tube leakage or improper modification will cause the engine control disorders also affect the brake actuator so advise the reader try not improper modification of the vacuum tube, in order to maintain the safety of the driving.
The design of the intake manifold is also very demanding, in order the same as the combustion condition of the engine for each cylinder, each cylinder and the length of the manifold, and bending degrees should, as far as possible the same. Because the engine is four stroke to complete the operation program, so the engine each cylinder in a pulsed manner, the intake air, based on experience, the longer a manifold suitable for a low speed operation, while a shorter manifold is suitable for high-speed operation. Some models use a variable-length intake manifold, or continuously variable length intake manifold so that the engine can play a better performance in the speed domain.