29-12-2012, 01:45 PM
Two Stroke Petrol Engine
Two Stroke Petrol Engine.pptx (Size: 4.15 MB / Downloads: 43)
Heat engine
A heat engine is a device which transforms the chemical energy of a fuel into mechanical energy and uses this energy to produce mechanical work
Internal Combustion Engine
It is a type of engine in which, the combustion takes place due to fuel inside the cylinder.
Classification of internal combustion engine:-
(I). According to the fuel used:-
(a). Petrol engine
(b). Diesel engine
©. Gas engine
(II). According to the stroke:-
(a). Two stroke engine
(b). Four stroke engine
(III). According to the number of cylinder:-
(a). Single cylinder engine
(B). Multi-cylinder engine
(IV).According to the name of cycle:-
(a). Otto cycle
(b).Diesel cycle
Parts of an internal combustion engine are as follows-
Cylinder
Cylinder head
Piston
Piston rings
Gudgeon pin
Connecting rod
Crank shaft
Fly wheel
Fuel pump
Fuel filter
Air filter
Cam shaft
Spark plug
Carburetor
Rocker arm
Inlet , outlet valves and ports
Rocker Arm
Cylinder head-
The cylinder head closes one end of the cylinder and it casted a one piece and is bolted to the top of the cylinder . It contains the valve seats and ports and supports the valves and valves-actuated mechanism.
Piston-A piston is a metal cup with its crown facing the combustion space . The function of piston is to confine the gases in the combustion space and thus transmit the full force of expansion to connecting rod and crank shaft
Piston rings-
The leakage of gases between the walls of piston and cylinder is prevented by means of three to six iron rings which may be square or rectangle in cross section. These rings are inserted in grooves provided in piston .
Crank shaft-The reciprocating motion of the piston is converted into rotary motion by the crank shaft . And all mechanical transmission are geared by the power obtained by crank shaft
Working of Two Stroke Petrol Engine:-
The working of two stroke petrol engines are completed in two steps:-
(i)Suction and Compression
(ii) Expansion and Exhaust
Suction and Compression:- As the piston moves upwards both transfer port and exhaust port are covered by piston and the charge trapped in the cylinder is compressed by the piston in upwards movement. At the same time, the partial vacuum is created into crank case and the fresh charge enters the crank case.
Power and exhaust:- The burning gases exerts pressure on top of the piston and the piston is forced downwards as a result of pressure generated. As pressure descends through about 80% of the expansion stroke the exhaust port is uncovered by the piston and the combustion gases leave the cylinder by pressure difference and at the same time underside of piston causes compression of charge taken into crankcase.