IC ENGINE TERMINOLOGY
The following terms/Nomenclature of an engine are explained below:
1. Bore:
The nominal inside diameter of the engine cylinder is called bore.
2. Top Dead Centre (TDC):
The extreme position of the piston at the top of the cylinder of the vertical engine is called top dead centre (TDC),
In case of horizontal engines. It is known as inner dead centre (IDC).
3. Bottom Dead Centre (BDC):
The extreme position of the piston at the bottom of the cylinder of the vertical engine called bottom dead centre (BDC).
In case of horizontal engines, it is known as outer dead center (ODC).
4. Stroke:
The distance travelled by the piston from TDC to BDC is called stroke.
In other words, the maximum distance travelled by the piston in the cylinder in one direction is known as stroke.
It is equal to twice the radius of the crank.
5. Clearance Volume (Vc):
The volume contained in the cylinder above the top of the piston, when the piston is at top dead centre is called the clearance volume.
6. Swept Volume (Vs):
The volume swept by the piston during one stroke is called the swept volume or piston displacement.
Swept volume is the volume covered by the piston while moving from TDC to BDC.
7. Total Volume= Cylinder
volume (V): Total volume of the cylinder.
V= Vs + Vc
8. Compression Ratio (rc):
Compression ratio is a ratio of the volume when the piston is at bottom dead centre to the volume when the piston is at top dead centre.
The compression ratio varies from 5 : 1 to 10 : I for petrol engines and from 12:1
to 22 : I for diesel engines.
9.Crank Throw:
The crank
throw is
the measurement from the center of the crankshaft to
the center of the crankpin journal.
It is
used to determine the stroke of an engine.The throw is
equal to one-half the stroke. The
longer
the throw,
the greater the stroke, or distance, a piston travels.
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