A piston is a device of the engine which reciprocates inside the combustion chamber of the engine. The piston is the heart of the reciprocating engine. It consists of a movable circular metal with a piston ring, which, after being installed in the engine cylinder, can be hermetically sealed. The piston is connected to the connecting rod via the piston/shaft pin, which in turn is connected to the crankshaft.
In four-stroke car engines (petrol and diesel), the processes of absorption, compression, combustion, and output occur at the top of the piston in the cylinder head, forcing the piston up and down (or in and out). Shown on the flat motor) in the cylinder, rotates the crankshaft.
It moves in the cylinder and the force of the expanding gas is transmitted to the piston connecting the shaft to the crankshaft and in the opposite direction to the crankshaft. The compressed gas allows the injection of liquid into the cylinder. It also acts as an inspection valve.
Used as a heat transfer device for the cylinder wall.
The main purpose of the piston is:
- Reducing inertia also improves the mechanical performance of the engine.
- It compresses the liquid inside the cylinder, thereby increasing the pressure and temperature of the liquid in the cylinder.
- It also offers directions.
How does Piston work?
When the engine is running, the piston goes up and down the cylinder. When it reaches the pivot point, its speed decreases and then suddenly accelerates again. These forces create static forces on it. When combined with the force produced by the gas pressure, it creates the force of the piston, which is obtained at the joint axis and the crankshaft.
The crankshaft is completely vertical only in the axial points above and below. Press the connecting angle of the piston shaft towards the cylinder wall. The force and direction of this force change continuously during the combustion cycle because it depends on the power of the piston and the angle between the piston crown and the connecting axis of the shaft. It has a piston ring. They secure the combustion chamber and the working room to the crankshaft. They can also remove oil from the cylinder wall and thus control fuel consumption. The piston ring also releases the heat absorbed by the piston on the surface of the drive cylinder during the combustion cooling process.
Types of Pistons
1) “Lo-Ex” alloy Pistons
Lo-Ex is the name of a light alloy for pistons which means low-temperature expansion. includes the following options:
Silicon 11 to 13
Nickel 0.7 to 2.5%
Aluminum from 86.3 to 82.5
The coefficient of expansion is actually only 2 smaller than that of pure aluminum, but this improvement, along with excellent resistance to wear and heat, changes the alloy.
2) Specialloid Pistons
Specialloid manufactures a variety of pistons for commercial vehicles, industrial stationery, railways, traditional and auxiliary lenses, automobile gasoline engines, and diesel engines.
Modern alloy diesel pistons have vertical gears and sturdy columns on the inner surface of the skirt, which transfer the load directly from the top to the bearing area of the pin.
The components of the crown, ring, and shell are proportionate to the thermal properties, resulting in a significant reduction in the operating temperature, a reduction in the tendency of the ring to stick, and thermal cracking in the area of the side valve sleeve. Burn the bowl.
The preferred material is a high strength, low expansion alloy with a silicon content of 11-12, called an S.132 spilled. A sudden change in the cross-sectional area obstructs the flow of heat. The figure shows a typical heavy heat flow piston used in high-power diesel engines.
3) Wellworthy Pistons
UK Wellworthy Ltd manufactures high load pistons and the upper ring uses a cast-iron ring retainer. These cap brackets were recently applied to a ring on a piston of a diesel engine. Compared to unprotected light alloys, maximum groove wear is minimized. Al-Fin bonding process is used to position the frame ring, which prevents any risk of penetration into the loosening, as well as overcoming the extreme hardness of aluminum oxidation in the casting process.
The working conditions were not so severe as to indicate that the grooves were successfully protected in the anodizing process in gasoline engines by the use of inserts.
- It has good hardness and can withstand a lot of pressure.
- The weight reduces the weight of the convertible, resulting in a higher engine speed.
- Good thermal conductivity reduces the risk of shock and thus achieves a higher compression ratio.
- Silence during work.
- Low expansion materials allow for different expansion rates of cast iron cylinder blocks and aluminum pistons.
- A well-shaped skirt can provide uniform pads in working conditions.