Piston for Automobile Engines - Design Considerations
Piston - Description
A piston is cylinder with a disc at the top. It reciprocates within a cylinder and is moved by the expanding combustion gas and also moves the gas or fluid that enters the cylinder and compresses it. The piston of an I.C. engine receives the impulse and energy from the expanding gas that was combusted and transmits this energy to the crank through the connecting rod.
Basic design considerations
1. The piston must have the strength to resist the impulse and inertia forces.
2. Ability to disperse the heat of combustion and avoid thermal distortion.
3. Sealing the gas and oil
4. Sufficient bearing area to work for large number of reciprocating cyles
5. Minimum weight
6. Smooth noiseless operation
7. Provide adequate support for piston pin
Trunk pistons are used for I.C.Engine. Truck piston refers to pistons with long skirt.
The piston has a head, hollow to accommodate the gudgeon pin or wrist pin and skirt. It also has grooves to accommodate piston rings and grooves for oil passage.
Materials for Piston
Aluminium alloys (Aluminum) and various alloys of cast iron are used. Meehanite is also used. Malleable cast iron is also used.
Elements of Machine Design, N.C. Pandya and C.S. Shah, Fifth Edition, 1973, Charotar Book Stall, Anand, India