AUTOMOBILES AND AUTOMOTIVES: POWERPLANTS

INTRODUCTION

Power plant of an automobile is that component or part which produces power to drive the automobile. It is in the form of an internal combustion engine running on petrol or diesel. It can be a gas turbine or steam engine. These are called external combustion engines.

This unit mainly covers various aspects of internal combustion engines from concept to their principle of working. In case of an internal combustion engine combustion of fuel with air takes place inside the engine cylinder.

CLASSIFICATION OF IC ENGINES

IC engines may be classified on different bases. Some of the main classifications are given below:

ACCORDING TO FUEL USED

(a) Petrol engine

(b) Diesel engine

(d) CNG (Compressed Natural Gas) engine

ACCORDING TO CYCLE OF OPERATION

(a) Two stroke engines

(b) Four stroke engines

ACCORDING TO CYCLE OF COMBUSTION

(a) Otto cycle engines which work on Otto cycle.

(b) Diesel cycle engine which work on diesel cycle.

ACCORDING TO METHOD OF IGNITION

· SPARK IGNITION (SI) ENGINES

These engines are petrol engines in which a spark plug is used to ignite the fuel-air mixture.

· COMPRESSION IGNITION (CI) ENGINES

Diesel engines are CI engines in which air is compressed to such a high pressure and temperature so that burning of fuel takes place as soon as it is injected into the cylinder due to high temperature.

FOUR STROKE ENGINES VS TWO STROKE ENGINES

Four stroke engines are those engines in which one engine cycle is completed in two revolutions of crank shaft or four piston strokes. Various piston strokes are : suction, compression, power and exhaust.

In two stroke engines, the entire cycle is completed in one revolution of crank shaft or two piston strokes.

1. Four Stroke Cycle: