CLASSIFICATION OF IC ENGINES

CLASSIFICATION OF IC ENGINES

There are many different types of IC engines and they can be classified on the following basis:

a. Thermodynamic Cycle:

1. Constant Volume or Otto Cycle-the heat energy is added to the system at constant volume
2. Constant Pressure or Diesel Cycle-the heat energy is added to the system at constant pressure. Limited Pressure or Dual cycle the heat energy is added to the system partly or constant volume and partly at constant pressure.
3. Joule or Brayton Cycle-heat energy is added at constant pressure and the heat energy is rejected also at constant pressure whereas in Otto, Diesel and Dual cycles, the heat energy is rejected at constant volume.

b. Number of Strokes per Cycle:

1. 4-stroke engines the thermodynamic cycle is completed in four strokes of the piston.
2. 2-stroke engines the thermodynamic cycle is completed in two strokes of piston.

c. Ignition System:

1. Spark Ignition (SI) a combustible homogeneous air fuel mixture prepared by the carburetor and sucked inside the cylinder is Ignited with the help of a spark plug.
2. Compression Ignition (CI) the fuel is injected inside the system and it automatically ignites in presence of high temperature and high pressure air (compressed within the system prior to the injection of fuel) present inside the system
3. Pilot injection of fuel oil in gas engines.

d. Fuel Used:

1. Petrol engine the engine uses petrol or gasoline as the source of energy
2. Oil engine uses diesel oil, mineral oil etc., as fuel
3. Gas engines uses gaseous fuel (coal gas, natural gas, coke oven gas, producer gas etc.,
4. Multi fuel engines use gasoline or diesel oil for starting purpose and kerosene or biogas as primary fuel.

e. Cooling Arrangement:

1. Water cooled cylinder walls are cooled by circulating water
2. Air cooled walls of the system are cooled by blowing atmospheric air over hot surfaces (motor cycles. scooters, aircrafts have air cooled engines).

f. Arrangement of Cylinders:

Multi-cylinders engines are invariably used in automobiles. The upper limit on the size of the cylinder is determined by the dynamic considerations, i.e., when the reciprocating masses of the piston and connecting rod are accelerated and decelerated, inertia forces develop and they put a limit on the speed of the engine and thus on the power output. Therefore, the displaced volume is distributed amongst several smaller cylinders. By this means, the Inertia forces per cylinder are reduced and the forces in one cylinder can easily be balanced by an appropriate arrangement of other cylinders.