Motor Fuel piston

Combustion piston (piston) consists of a cylinder which equipped with a piston. The piston moves in translation then by the crankshaft is converted into motion spins.

1. Otto Cycle - Gasoline Motor (constant volume air cycle)

A. Motor 4 stroke

Is the motor that requires four times the step piston(twice up and twice down) to obtain one-time effort in the combustion chamber. Step piston motion The succession is:

1. Intake stroke

In this step intake valve open and valve expenditure(exhaust)is closed. Piston function of the TMA to TMB, the volume increases pressure decreases, the fuel + air sucked into the cylinder, but because the cylinder connected with the outside air, so the air pressure on the cylinder at the end of the suction step remains an atmosphere.

2. Compression stroke

In this step the valve intake and exhaust closed. Piston moves from the TMB to the TMA. Fuel + compressed air with the isentropic and the pressure on end of compression of about 7 atm.
The combustion process in which the valve and the intake valves closed and the exhaust air + fuel burned because the electrical spark jumps from the spark plug. this process regarded as the entry process heat.
C8H18 + 12,5      > O2 8 CO2 + 9 H2O + Heat

3. Power stroke

In this step the valve fixed income and expenditure closed. Since the pressure rise due to heat
combustion, resulting in piston driven and generate employment. Piston moves from TMA to the TMB.
The process of heat dissipation, the current intake valve and expenses covered, some of the heat removed through process of radiation, convection and propagation in metallic materials of the cylinder.

4. Step disposal of combustion (exhaust stroke)

In this step intake valve closed and valve open expenditures, piston moves from TMA to TMB crowd out the rest of the combustion on the cylinder and this process occurs at constant pressure.


B. Motor 2 Stroke

Is a machine that required two steps piston (one-time upward / ascending strokes and once to Under / discending stroke) to obtain a one-time businesses in the combustion chamber.

1. Step up

The piston moves upward in the combustion chamber will occurs with the compression and spark jumps electricity to spark plugs, fuel combustion occurs in the space combustion. In the crankcase chamber, with the piston movement upwards, the volume is getting bigger and the pressure becomes smaller than the outside air, so that outside air into the crankcase through the carburetor and there mixing air and fuel in the crankcase.

2. Step down

The piston moves down in the combustion chamber occurs business measures. By the time the piston reaches the hole exhaust (exhaust port), the rest will come out firing and when the piston reaches the hole flushing
(scavenging ports), a mixture of fuel and air from crankcase chamber into the combustion chamber. In the crankcase space volume will drop and the pressure grew, so that the mixture of air and fuel going into
combustion chamber through a hole flushing.