Basic components of Engine
The engine component parts must be strong, wear-resistance and durable.
The following are the main components of an Automobile engine.
1) Cylinder
2) Cylinder head
3) Gaskets
4) Crank case
5) Oil pan
6) Cylinder liners
7) Piston rings
8) Piston rings
9) piston pin
10) Connecting rod
11) Crank shaft
12) Flywheel
13) Cam shaft
1) Cylinder Block
It is the main blocks of the engine which contains cylinders. It provides housing for the crank and cam shafts and other engine parts.
It forms the basic frame work of the engine. The other parts of the engine are attached to it (or) fitted in it. It thus forms the main body for the engine.
At the bottom part of the block, crank shaft is held in bearing which are surrounded by the oil sump.
All the top of the block, cylinder head is held with it through gasket.
Cylinder block are made of alloy cast iron. Nowadays Aluminium alloy cylinder block are being widely used in mopeds and cars.
2) Cylinder head
The cylinder head is a single casting bolted to the top of the cylinder block. It contains holes for screwing spark plugs.
Water passages and combustion chambers are formed in the cylinder heads.
In addition to this, in engines having overhead valve system, the head have openings for valves and valve seats.
The head also supports rocker shaft along with rockers. Diesel engines cylinder heads have holes for screwing injectors.
The lower surface of the head is machined perfectly so as to be bolted properly to the machined upper surface of the cylinder block.
A gasket between head and block surface ensure that there is no leakage of gas. It is made of high grade graphite cast iron (or) Aluminium alloy.
3) Gaskets
Gasket are used to provide sealing and a tight fitting joint between two surfaces
Main places namely the joint between cylinder head and block, crank case joint, manifold and water pump joints.
Main requirements of gaskets are
1) The gasket should be resistance to the chemicals.
2) It should be with stand high heat produced in the combustion.
3) It should not be damaged by cooling water circulation.
Gaskets are made of Asbestos, cork, thin sheet steel.
4) Crank case
The oil pan and the lower part of the cylinder block together is called crank case. Crank case is attached to the bottom face of the cylinder.
It acts as the case of the engines. It supports the crank shaft and cam shaft in suitable bearing and provides the arms for supporting the engine on the frame.
It is usually made of ferrous alloy or semi steel to provide a stronger and harder casting.
5) Oil pan
Oil pan or sump is used for storage of lubricating oil. A gasket is used between crank case and oil pan. Aluminium or pressed steel materials is used as oil.
The oil pan has a shallow downward slope at one end which combines with deep reservoir. A drain plug is provided to drain out the dirty oil at the time of oil service.
6) Cylinder liners
Liners is a bore or sleeve fitted into the cylinder box. The piston slides in the liner. Cylinder block is a major part of an engine.
So the liner is produced as detachable part of the engine block. Thus the engine block is prevented from Reboring directly.
The ovality of bore can be easily machined. Over sized piston is available and hence the liner is repeatedly Rebored as per the size of piston.
7) piston
It is the heart of the engine. It is a gas tight movable cylindrical disk slides up and down in the cylinder.
It is function is to compress the fresh charge during the compression stroke and to transmit the force produced due to combustion of the charge to the connection rod and then to the crank shaft during the power stroke.
The piston is generally made of cast irons. Aluminium alloy is also used as it has higher thermal conductivity and is light in weight.
8) Piston rings
The piston rings are mounted in the circumferential grooves provided on the outer surface of the piston. These are circular in shape and are made of special grade cast iron.
Usually there are two sets of rings mounted on the piston.
The upper piston rings are called compression rings and their function is to provide gas tight seal and to prevent leakage of high pressure gas.
The lower piston rings are called oil control rings whose function is to provide effective seal and to prevent the leakage of oil into the engine cylinder.
9) Piston pin
Piston pin or gudgeon pin is used to connect the piston and the connecting rod. It is made as tabular form and light weight.
It passes through the bosses in the piston and the small end of the connecting rod. It is made of low carbon case hardened steel.
10 ) Connecting rod
It provides connection between the piston between the piston and the crankshaft. Its length is kept twice the stroke.
Its small end which is connected to the piston may be solid eye, split eye or slotted type. The big end which is connected to the crank shaft pin is split type and has separate cap.
The cap is bolted to the body of the rod safely. In some through holes may be provided for lubricating purpose.
The connecting rods are mostly of I - section and are made of forged steel. It must have great strength and rigidity combined with light weight.
11) Crank shaft
Crank shaft converts the reciprocating motion of the piston into rotary motion.
The main parts of the crank shaft are crank pins, main journals, balance weight, webs and flywheel flange range. It contains oil passages for lubrication.
It carries a timing gear and vibrations damper at the front end a fly wheel at the rear end. The crankshaft is a single piece casting.
The material used for the crank shaft is high carbon steel. Alloyed by copper, chromium and silicon.
12) Fly wheel
Fly wheel is mounted on the crankshaft. Its function is to maintain the speed fairly constant. Flywheel stores excess energy during the power stroke and returns it during the other stroke.
A ring gear is mounted over the flywheel which meshes with the self- starter drive pinion for cranking the engine. the rear face of the flywheel of the flywheel also serves as driving.
13) Cam shaft
One or more high lobes provided on a rotating circular section is called cam. It converts the rotary motion of the cam shaft into straight line motion.
Thus the cams are to open and close the intake and exhaust valves. A cam shaft contains a number of cams.
For each engine cylinder, there are two cams, one for each of the two valves cam shaft is also to drive the spark ignition distribution of the engine.
The material used for cams and camshaft is alloy steel or alloy cast iron. It is rotated at half speed of the crank shaft. the cam shaft is driven by the crankshaft by meshing gears.
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