CLASSIFICATION OF I.C. ENGINES

The internal combustion engines are classified according to .

1. Cycle of operation. They are divided into the following group.

(a) Two-stroke engines. In two-stroke engines, there is one power stroke in every two strokes or one rotation of the crankshaft.

(b) Four-stroke engines. In four-stroke engines, there is one power srrolte in every four strokes or one during two rotations of the crankshaft,

2. Cycle of operation. They are divided into the following groups :

(a) Otto-cycle. (b) Diesel cycle. (c) Dual cycle.

The operations of these cycles are discussed in the previous chapter

3. The fuel used. On this basis they are classified as :

(a) Petrol engines. (b) Diesel engines or heavy oil engines. (c) Gas engines.

4. The method of ignition. On this basis, they are divided into the two following classes.

(a) Spark ignition engines. (S.I. engines) and (b) Compression ignition engines. (C.I. engines).

5. The method of cooling. On this basis they are classified into two groups.

(a) Air-cooled engines. (b) Water-cooled engines.

6. The method of governing

(a) Quantity governing. (b) Quality governing. (c) Hit and Miss-governing.

7. The use of engines. The following is the classification on this basis :

(a) Stationary engines. (b) Automobile engines or engines for road vehicles.

(c) Marine engines. (6) Aero-engines. (e) Locomotive engines.

8. The arrangement of the cylinders. They can be classified as given below :

(a) Inline engine. All the cylinders are arranged in a line and the power is taken from a single crankshaft.

This arrangement is used in automobiles.

(b) V-type. It is a combination-of two inline engines set at an 'angle. The angle of V may vary from

30" to 75".

The length of the crankshaft of V-type engine is half of the crankshaft used for inline engine. This type is also used in automobiles.

(c) Opposed piston engine. The pistons reciprocate in a common cylinder having common combustion chamber at the centre. Opposed piston type is used in small air crafts and in some diesel installations.

(d) Radial engines. All the cylinders are set along the radius of a circle. The connecting rods point towards the centre of the circle. The connecting rods of all the pistons work on a single crank pin which rotates around the centre of the circle. The radial engine occupies little floor space and simplifies the balancing problems. This type was popular in aircrafts.

(e) Rotary engine. The engine consists of three-sided convex-type piston rotating in a cylinder. This type of engine is known as 'Wankel' engine. It is of high speed-type, light in weight and works on spark ignition system.