Key points of intake stroke in aviation piston engines

The key points of the intake stroke of an aviation piston engine are as follows:

1. Intake valve opening and closing

Intake valve opening: At the beginning of the intake stroke, the intake valve at the cylinder head opens, allowing fresh air (for aviation piston engines, it is usually a mixture of gasoline and air) to enter the cylinder.

Exhaust valve closed: At the same time, the exhaust valve remains closed to prevent exhaust gas from escaping from the cylinder.

2. Piston movement

Piston downward movement: The piston starts from the top dead center (i.e., the highest point of the piston movement in the cylinder) and moves downward to the bottom dead center (i.e., the lowest point of the piston movement in the cylinder).

Cylinder volume change: As the piston moves down, the volume inside the cylinder gradually increases, creating a certain degree of vacuum.

3. Inhalation of the mixed gas

The mixture enters the cylinder: Due to the negative pressure formed inside the cylinder, fresh mixture is drawn into the cylinder through the open intake valve under the action of atmospheric pressure.

The mixture ratio: In an aviation piston engine, the mixture is typically composed of gasoline and air, with a ratio usually being 1:15, meaning that 15 kilograms of air are needed to burn one kilogram of gasoline.

4. The function of the intake stroke

Preparing for combustion: The intake stroke provides the necessary mixture for the subsequent compression stroke and combustion stroke, and it is the first important step in the engine's operation.

Impact on engine performance: The smoothness of the intake stroke directly affects the combustion efficiency and power output of the engine. If the air intake is not smooth, it will cause the mixture to be too rich or too lean, thereby affecting the normal operation of the engine.

5. Auxiliary function of the intake system

Intake pipe: During the intake stroke, the mixture enters the cylinder through the intake pipe. The design and layout of the intake pipe will affect the intake efficiency.

Intake filter: In some aviation piston engines, the intake system also includes an intake filter, which is used to filter the air entering the cylinder and prevent impurities from entering the cylinder interior.

Turbocharger (optional) : To enhance high-altitude performance, some aviation piston engines are equipped with a turbocharger in the intake system, which increases the intake pressure and boosts the engine's power output.

6. The end of the intake stroke

Intake valve closed: When the piston moves to the bottom dead center, the intake stroke ends. At this point, the intake valve closes, preparing to enter the next stroke - the compression stroke.

In summary, the intake stroke of an aviation piston engine is the first crucial step in its operation. By precisely controlling the movement of the intake valve and the piston, it ensures that fresh mixture smoothly enters the cylinder, providing necessary preparations for the subsequent combustion process.