Intake manifold intake system engine

For carburetor or throttle body gasoline injection engine, intake manifold refers to the intake pipe from the back of carburetor or throttle body to the front of cylinder head intake. Its function is to distribute the mixture of air and fuel from carburetor or throttle body to the air inlet of each cylinder.

For port fuel injection engines or diesel engines, the intake manifold only distributes clean air to the intake of each cylinder. The intake manifold must distribute the air-fuel mixture or clean air to each cylinder as evenly as possible, so the lengths of gas passages in the intake manifold should be as equal as possible. In order to reduce airflow resistance and improve intake capacity, the inner wall of intake manifold should be smooth.

Intake pipe heating.

The intake manifold temperature of carburetor or throttle body fuel injection engine is very important. If the temperature is too low, gasoline will condense on the pipe wall. Therefore, the intake manifold of this kind of engine should be properly heated to promote the evaporation of gasoline. However, overheating will reduce the amount of air-fuel mixture entering the cylinder and reduce the engine power. Generally, the intake manifold is heated by engine exhaust or circulating coolant. To heat the intake manifold with circulating coolant, it is necessary to set a water jacket in the intake manifold and communicate with the engine cooling system so that the coolant can circulate in the water jacket of the intake manifold. The intake manifold of a fuel injection engine does not need to be heated.

Resonant air intake system

Because the intake process is intermittent and periodic, a certain amplitude of pressure wave will be generated in the intake manifold. This pressure wave propagates and reflects back and forth in the intake system at the local sound speed. If the resonant intake system consists of an intake manifold with a certain length and diameter and a resonant chamber with a certain volume, and its natural frequency is tuned to the intake period of the valve, then at a certain speed, before the intake valve closes, a large pressure wave will be generated in the intake manifold, which will increase the pressure and intake volume of the intake manifold. This effect is called intake fluctuation effect. Resonant air intake system has the advantages of no moving parts, reliable operation and low cost. But it can only increase the intake air and engine torque at a specific speed.

Variable intake manifold

In order to make full use of the fluctuation effect of intake air and minimize the difference between high and low intake speeds of the engine, so as to improve the economy and power of the engine, especially the economy and power of medium and low speeds and small and medium loads, it is required that the engine be equipped with a thick and short intake manifold at high speeds and heavy loads. The slender intake manifold is used for medium and low speed and medium and small load. Variable intake manifold is designed to meet this requirement. Variable intake manifold can increase engine torque by 5% on average at all speeds.