For a carburetor or throttle body gasoline injection engine, the intake manifold refers to the intake line after the carburetor or throttle body and before the cylinder head intake port. Its function is to distribute the air and fuel mixture to the intake ports of each cylinder from the carburetor or throttle body.
For an air-fuel injection engine or diesel engine, the intake manifold simply distributes clean air to the intake ports of each cylinder. The intake manifold must distribute air, fuel mixture, or clean air as evenly as possible to the individual cylinders. For this reason, the length of the gas flow channels in the intake manifold must be as equal as possible. In order to reduce the resistance to gas flow and improve the air intake capacity, the inner wall of the intake manifold should be smooth.
The main advantages of plastic intake manifolds are lower cost and lighter weight. In addition, due to the lower thermal conductivity of PA than aluminum, the temperature of the fuel nozzle and the incoming air is lower. Not only can improve the hot start performance, increase the power and torque of the engine, at the same time can avoid heat dissipation in the pipe to a certain extent during cold start, and accelerate the increase of the gas temperature, and the inner wall of the plastic intake manifold is smooth, which can reduce the air flow resistance and improve the engine Performance.
In terms of cost, the material cost of plastic intake manifold and aluminum intake manifold is basically the same. The plastic intake manifold is formed once, and the qualification rate is high. The aluminum casting manifold has a low casting yield and a high machining cost. Therefore, the production cost of plastic intake manifold can be 20% -35% lower than that of aluminum intake manifold.
1) High temperature resistance: The plastic intake manifold is directly connected to the engine cylinder head, and the temperature of the engine cylinder head can reach 130 ~ 150 ℃. Therefore, it is required that the plastic intake manifold material can withstand a high temperature of 180 ° C.
2) High strength: The plastic manifold is installed on the engine, and it must bear the vibration load of the automobile engine, the inertia load of the throttle and sensors, the pulsation load of the intake pressure, etc., and it must be guaranteed not to be subject to high-pressure pulsation pressure when the engine is abnormally tempered blasting.
3) Dimensional stability: The dimensional tolerance of the connection between the intake manifold and the engine is very strict, and the sensors, actuators, etc. on the manifold must be installed accurately.
4) Chemical stability: The plastic intake manifold directly contacts gasoline and antifreeze coolant when working. Gasoline is a strong solvent. The glycol in the coolant will also affect the performance of plastic. Therefore, plastic intake manifold The chemical stability of the tube material is very demanding and needs to undergo rigorous testing.
5) Thermal aging stability; automotive engines operate at very harsh ambient temperatures, and the operating temperature changes back and forth between 30 and 130 ° C. The plastic material must ensure the long-term reliability of the manifold.