The intake manifold
1, the basic knowledge
Before addressing the intake manifold, let’s think about how the air enters the engine. In the introduction we mentioned engine operation piston within the cylinder when the engine is in the intake stroke, the piston downward movement to produce the cylinder vacuum (that is, the pressure is reduced), good produce and the outside air pressure difference, so that the air You can enter the cylinder. For example, it should have been played pin, have seen the nurse how to inhale medicine needle barrel now! The engine is a virtual needle barrel, the barrel when the needle piston withdrawn outwardly medicine is drawn into the needle barrel, and so air into the engine is a cylinder.
due to the low temperature of the inlet end, the composite material started to become popular intake manifold material, which is light and smooth interior, can effectively reduce resistance, increase the efficiency of the intake air.
2, the intake manifold description
Causes name
is located in the intake manifold between the throttle valve and the engine intake, is called “manifold “because the air into the throttle, after manifold buffer system, air flow channel in this” disagreement “, and a corresponding number of engine cylinders, such as the four-cylinder engines have four, five-cylinder engine, there are five , air is introduced into each cylinder respectively. In naturally aspirated engine, since the intake manifold after the throttle valve is located, so when the throttle opening degree of the air can not be sucked into the cylinder a sufficient amount of the engine, it will cause the manifold vacuum is high; and when the engine throttle opening when a large degree, the degree of vacuum in the intake manifold becomes small. Thus, the injection engines will supply a pressure gauge mounted on the intake manifold, the engine ECU determines that the load is supplied, and the fuel injection amount administered.
different purposes
manifold vacuum only may be used to supply determination engine load pressure signal, there are many uses it! Such as brakes also need to use a vacuum to assist the engine, so the engine is started when the brake pedal will be a lot of light, it is because there is a vacuum-assistedreason. There are some forms of cruise control means also using the vacuum manifold. These vacuum if there is a leak or improper modification will cause the engine control disorders, will also affect the actuation of the brakes, so try not to advise readers on a vacuum tube for improper modification, in order to maintain traffic safety.
ingenious design
of the intake manifold design is very demanding, for each cylinder of the engine combustion conditions the same, have the same length of the manifold as much as possible and the curvature of each cylinder. Since the engine is a four stroke to complete the operation program, so that each engine cylinder intake air pulse will, based on experience, the longer manifold for low speed operation, while shorter manifold is suitable for high speed operation. Therefore, some models will use the variable-length intake manifold, or continuously variable-length intake manifold, so that the engine can play a better performance in the rotation speed region.
3, different definitions
For the carburetor or throttle body fuel injection engine, the intake manifold means after the throttle body or carburetor to the cylinder head intake intake line before the road. Its function is to air and fuel mixture from the carburetor or throttle body assigned to the respective cylinder inlet.
airway diesel or fuel injection engine, the intake manifold is only assigned to the clean air intake port of each cylinder. The intake manifold must be as uniform distribution of air, clean air or the fuel mixture to each cylinder, for the length of the intake manifold gas flow path should be as equal as possible. In order to reduce the gas flow resistance, increase the intake capacity of the inner wall of the intake manifold should be smooth.