What are the Main Parts of an Automobile Engine?
An internal combustion engine is an engine in which combustion (burning of fuel) takes place inside the cylinder of the engine. By burning of the fuel high temperature and pressure force generates. This pressure force used to move the vehicle or rotate wheels by use of some mechanism.
In an engine many parts work together and achieve the goal of converting the chemical energy of fuel into mechanical energy. These parts are bolted together and the combination of all these parts is known as an engine. Today I am going to tell you about these parts and how they work so you can know the basics of automobile engines.
- It is a container fitted with a piston, where the fuel is burnt and power is produced.
- Cylinder is the main body of the IC engine. Cylinder is a part in which the intake of fuel, compression of fuel and burning of fuel take place. The main function of the cylinder is to guide the piston.
- For cooling of the cylinder a water jacket (for liquid cooling used in most cars) or fin (for air cooling used in most of the bikes) is situated at the outer side of the cylinder.
- At the upper end of the cylinder, the cylinder head and at the bottom end crankcase is bolted.
- Material: Ductile (Nodular) Cast Iron,30C8 (Low Carbon Steel)
- Manufacturing method: Casting, Forging and after that heat transfer, Machining
2.Cylinder Head/Cylinder Cover:-
- One end of the cylinder is closed utilizing a cylinder head. This consists of an inlet valve for admitting air-fuel mixture and exhaust valve for removing the products of combustion.
- The inlet valve, exhaust valve, spark plug, injector, etc. are bolted on the cylinder head. The main function of the cylinder head is to seal the cylinder block and not to permit entry and exit of gases on the cover head valve engine.
- Function: It provides the housing for exhaust and intake valves, threaded holes for the spark plugs or fuel injector and necessary linkages, passage for cooling jackets and passages for the fuel and air mixture.
- Material: Aluminium alloys
- Manufacturing Method: Casting, Pressure Die Casting, forming.
- Piston is used to reciprocate inside the cylinder.
- It transmits the energy to the crankshaft through the connecting rod.
- Material: Aluminum Alloy 4652 because of its Low Specific Gravity.
- Manufacturing Method: Casting
4. Piston Rings:-
- These are used to maintain a pressure-tight seal between the piston and cylinder walls and also it transfers the heat from the piston head to cylinder walls.
- These rings are fitted in grooves that have been cut in the piston. They are split at one end so they can expand or slipped over the end of the piston.
- Function of Piston rings:
1. To provide a pressure seal to prevent blow-by of burnt gases.
2. To form the main path for conduction of heat from the piston crown to the cylinder walls.
- Function of Compression Ring:
To control the flow of oil to the skirt and rings themselves in adequate quantity while preventing an excessive amount reaching the combustion chamber with consequent waste and carbonization.
- Material: cast iron of fine grain and high elastic material
- Manufacturing Method: Pot casting method
5. Connecting Rod:-
- One end of the connecting rod is connected to the piston through a piston pin while the other is connected to crank through a crank pin.
- It transmits the reciprocatory motion of the piston to the rotary crank.
- There are two ends of connecting rod one is known as the big end and other as small end. The big end is connected to the crankshaft and the small end is connected to the piston by use of piston pin.
- Function :
1) It converts the reciprocating motion of the piston into rotary motion of crankshaft.
2) It connects piston to the crankshaft.
- Material: Low Carbon steel 30C8
- Manufacturing Methods: Forging and after that heat treatment.
- It is a lever between connecting rod and crankshaft.
- The function of the crankshaft is to transform reciprocating motion into a rotary motion.
- The crankshaft of an internal combustion engine receives the efforts or thrust supplied by the piston to the connecting rod and converts the reciprocating motion of the piston into rotary motion of the crankshaft.
- The crankshaft mounts in bearing so it can rotate freely.
- The shape and size of crankshaft depends on the number and arrangement of cylinders.
- Functions: 1. It converts the reciprocating motion to the rotating motion.
2. It transmits Power to the Flywheel.
3. It receives Power from flywheel.
- Material:37C15 Alloy Steel.
- Manufacturing Method: Forging
- The flywheel is a rotating mass used as an energy storing device.
- A flywheel is secured on the crankshaft. The main function of the flywheel is to rotate the shaft during the preparatory stroke. It also makes crankshaft rotation more uniform.
- Function : 1. Flywheel absorbs energy during power stroke and supplies it during remaining strokes.
2. Flywheel keeps the crankshaft rotating at the uniform speed throughout in spite of Uneven power impulses of engine cylinders.
4. Flywheel carries the drive from the starting motors to crankshaft while the starting the Engine.
- Material: cast Iron
- Manufacturing Method: Casting
- It supports and covers the cylinder and the crankshaft. It is used to store the lubricating oil.
- The main body of the engine to which the cylinder is attached and which contains the crankshaft and crankshaft bearing is called crankcase. It serves as the lubricating system too and sometimes it is called oil sump. All the oil for lubrication is placed in it.
- A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially
obstructing various passageways.
- The intake and exhaust valves open at the proper time to let in air and fuel and to let out the exhaust.
- Note that both valves are closed during compression and combustion so that the combustion chamber is sealed.
- Materials: Phosphorus Bronze and Monel metal.
- The main function of a sparkplug is to conduct the high potential from the ignition system into the combustion chamber.
- It provides the proper gap across which spark is produced by applying high voltage, to ignite the mixture in the ignition chamber.
- Manufacturing Method: Each major element of the spark plug—the center electrode, the side electrode, the insulator, and the shell—is manufactured in a continuous in-line assembly process. Then, the side electrode is attached to the shell and the center electrode is fitted inside the insulator. Finally, the major parts are assembled into a single unit.
12. Engine Bearing:
- The crankshaft is supported by bearing.
- Everywhere there is rotary action in the engine, bearings are used to support the moving parts.
- Its purpose is to reduce the friction and allow parts to move freely.
- Function: The bearings hold the crankshaft in place and prevent the forces created by the piston and transmitted to the
crankshaft by the connecting rods from dislodging the crankshaft, instead forcing the crank to convert the reciprocating movement into rotation.
- A device for regulating automatically output of a machine by regulating the supply of working fluid.
- When the speed decreases due to an increase in load the supply valve is opened by a mechanism operated by the governor and the engine, therefore, speeds up again to its original speed.
- Thus the function of a governor is to control the fluctuations of engine speed due to changes in load.
- See: Introduction To Governors | Classification / Types Of Governors
- Fuel injection is a system for mixing fuel with air in an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s.
- The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure, while a carburetor relies on low pressure created by intake air rushing through it to add the fuel to the airstream.
- The fuel injector is only a nozzle and a valve: the power to inject the fuel comes from a pump or a pressure container farther back in the fuel supply.
- The main function of the manifold is to supply the air-fuel mixture and collects the exhaust gases equally form all cylinder. In an internal combustion engine two manifold are used, one for intake and other for exhaust.
- Function of inlet manifold:
1) Inlet manifold carries air fuel mixture from carburetor to engine cylinders.
2) It provides large enough space to allow sufficient flow of charge for maximum power and on other hand it must be small enough to maintain adequate velocity for keeping the fuel droplets suspended in air.
3) It should provide least resistance to flow.
4) In MPFI it facilitates the injection of fuel in inlet manifold before supplied to cylinder.
- Function of exhaust manifold:
1) The function of an exhaust manifold is to expel the exhaust gases from the combustion chamber of each cylinder out to the atmosphere through the exhaust pipe after combustion stroke is completed.
2) To keep back pressure minimum.
- Material: Aluminium alloy -Alloy 4600
- These are hardened steel parallel spindles fitted through the piston bosses and the small end bushes or eyes to allow the connecting rods to swivel. It connects the piston to the connecting rod. It is made hollow for lightness.
- Material: Plain Carbon steel 10C4
- Pushrod is used when the camshaft is situated at the bottom end of the cylinder. It carries the camshaft motion to the valves which are situated at the cylinder head.
- Rocker Arms are typically in between the pushrod and the intake and exhaust valves. They allow the pushrods to push up on the rocker arms and therefore push down on the valves.
- Material: Medium Carbon steel
- Manufacturing methods: Forging
- Camshaft is used in the IC engine to control the opening and closing of valves at proper timing.
- For proper engine output inlet valve should open at the end of the exhaust stroke and closed at the end of the intake stroke.
- So to regulate its timing, a cam is used which is oval and it exerts pressure on the valve to open and release to close.
- It is drive by the timing belt which drives by the crankshaft. It is placed at the top or the bottom of the cylinder.
- Function:1. Camshaft is responsible for opening of the valves. Cam shaft has number of cams along the length, two cams for each cylinder, one operates inlet valve and another operates exhaust valve.
2. The camshaft has a eccentric lobe which operates fuel feed pump.
3. A gear is present on the camshaft which drives ignition
distributor and oil pump.
- Material: Plain Carbon steel 10C4
- Manufacturing Method: Grinding, Case Hardening
21. Gasket :
1. Gasket is placed between cylinder head and cylinder block to retain compression in the cylinder.
2. Gasket prevents leakage of the gases from combustion chamber and ensures tight fit joint.
3. Gasket also withstands high pressure and high temperature.
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