Car Engine Parts and Functions with Pictures
In this post, we will discuss the engine parts. As you know that an engine is a machine designed to convert one form of energy into mechanical energy. Heat engines heat a fuel to make heat that can be used for work. The engine can be classified into two types: one is an internal combustion engine, and one is an external combustion engine.
- The internal combustion engine is those heat engines that burn their fuel inside the engine cylinder.
- External combustion engines are those heat engine that burns their fuel outside the cylinder engine.
The engine most essential part of automobile industries or we can say that the engine is the heart of an automobile. The function and construction of each engine parts of an internal combustion engine are explained. Here is the key to the engine.
Read More: car engine parts names with pictures
The Main Car Engine Parts Are as Follows:
- Cylinder Block
- Cylinder Head
- Crank Case
- Oil Pan
- Cylinder Liner
- A Piston Ring
- Connecting Rod
- Piston Pin
- Crank Shaft
- Engine Valves
- Poppet valve
- Sleeve valve
- Rotary valve
Read Also: List of 19 Car Interior Parts [Explained with Functions] PDF
1. Cylinder block
Fig shows a simple sketch of the cylinder block. This is the foundation of the engine. and one of the main in engine parts. Cylinder block, cylinder head and crankcase these three parts form the foundation and main stationary body of the automobile engine.
A cylinder block consists of three parts:
- The cylinder in which the piston slid up and down.
- The port or opening to the valves.
- The passages for the flow of cooling water.
Construction and working:
- The cylinder block is usually made of grey cast iron or aluminium and its alloys.
- The crankcase is secured to the block’s bottom. These other parts such as timing gear water pumps, ignition distributors, flywheels, fuel pumps and etc. can also be attached to the crankcase.
- Passages are provided in the cylinder walls for the circulation of cooling water.
- Mating surfaces of the block are carefully machined to provide a perfect sealing surface.
- Through drilled passages known as oil galleries, cylinder block can also carry lubrication oils to different components.
2. Cylinder Head
Another type of engine parts is cylinder head it is joint between the cylinder head and cylinder block.
- It is usually made up of cast iron and aluminium alloy.
- The top of the cylinder is covered by a separate cast piece know as the cylinder head.
- The cylinder head is attached to the cylinder block by means of studs fixed to the block gaskets are used to provide a tight, leak-proof joint between the head and block.
- The cylinder head has a combustion chamber that is above each cylinder.
- It contains valve guides, valve seats and ports. There are also coolant jackets, coolant jackets, spark plug threaded holes, and coolant jackets. It incorporates passages for the flow of cooling water.
- The cylinder head casts integrally with cylinder blocks also be done in a few cases usually in racing cars to obtain a gas-tight joint.
- There are many advantages to detachable heads over integral construction.
- For engines with high cooling requirements, such as racing cars, copper alloys might be used.
Types of Cylinder Head
Depending upon the valve and port layout, the cylinder head may be classified into three types as follows:
- Loop flow type
- Offset cross flow type
- Inline cross flow type
Loop flow type: In the loop, flow types the inlet and the exhaust manifolds are on the same side, which facilitates preheating of the intake air.
Offset cross flow type: Offset cross flow types the inlet and the exhaust manifolds are placed on different sides of the cylinder head.
In line cross flow type: In line cross-flow type, the valve is positioned transversely and usually inclined to each other, while the inlet and the exhaust manifolds are on different sides of the cylinder head. Although this arrangement is more efficient, it is also more expensive.
The oil pan and the lower part of the cylinder block together are called the crankcase. It is the bottom portion of the cylinder block, in which the crankshaft is fitted.
- This is a rigid construction made of grey cast iron or aluminium. It can either be cast with the block, or separately attached with bolts.
- The crankcase looks like a box with no bottom. Oil pan or sump forms the bottom half of the crankcase.
- The function of the crankcase is to provide support for the main journals and bearing of the crankshaft, rigidly maintaining the alignment of their axes of rotation under various engine loads.
- The crankcase is supported in the crankcase through a number of bearing called the main bearing.
4. Oil Pan
The bottom half of the crankcase is called the oil pan or sump. To prevent the crankcase from leaking, it is attached to it with set screws and sealed with a gasket. The oil pan serves as a reservoir for the storage, cooling and ventilation of engine lubricating oil.
At the bottom of the oil sump, a drain plug is provided to drain out the dirty oil at the time of oil replacement. Generally, the sump is made of pressed steel sheet or aluminium alloy casting is used.
The various functions of the oil pan as follows
- To store the oil for theengine lubrication system.
- Oil pan used to collect the return oil draining
- To serve as a container for impurities or foreign matters
- Oil pan provides for cooling of the hot oil in the sump.
- The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine.
- The oil runs into the pan and drains.
- Thus there is a constant circulation of oil between the pan and the working parts of the engine.
There are separate sets of pipes attached to the cylinder head which carry the air-fuel mixture and the exhaust gases, these are called manifolds. It is generally made of cast iron so that it is able to withstand the high temperature of the exhaust gases.
- It consists of the air intake, throttle body, intake manifold flange for tail-pipe and flange for a carburettor.
- The air goes into the air intake travels through, throttle body into the intake manifold and from there it goes into the engine through the cylinder head.
- The inletmanifold transports the air-fuel mixture from cylinders to carburettor.
- The exhaust manifold is the set of pipes carrying exhaust gases from the cylinder head to the exhaust system.
Also read: How does your engine react to the intake manifold? – thegoneapp.com
These are used to provide a tight fitting joint between two surfaces.
Gaskets are found in
- the joint between the cylinder head and the cylinder block
- Between crankcase and oil pan.
- Between the manifold and cylinder block.
Materials used for gaskets are
Requirement/properties of the gasket as follows
- Conformity: The gaskets should conform to the mating surfaces which may have roughness or warpage.
- Resistance: It should have resistance to high pressures, extreme temperature and vibrations.
- Impermeability: The gasket must be impermeable to the fluid.
- Resistance to chemical attack: the gasket should have resistant to the chemicals such as fuel, products of combustion, coolant and engine oil.
- Provision of apertures: The gasket must have apertures for any studs, bolts, opening etc.,
Gaskets produced by the fuel-pro USA as follows
- Cylinder head gaskets.
- Oil pan gaskets.
Types of gaskets used in engines
- Copper-asbestos gasket.
- Steel-asbestos gasket.
- Steel-asbestos-copper gasket.
- Gasket made of single steel ridged, or corrugated.
- Stainless steel gasket
7. Cylinder liners
These are cylindrical shapes used in the cylinders to avoid the problem of cylinder wear. It is one of the most important functional parts to make up the interior of an engine.
After they have worn out, these can be replaced. These are made of special alloy iron containing silicon, manganese, nickel and chromium.
These are typically cast centrifugally. These liners resist corrosion and wear. These liners are of the oil hardening type and offer considerably longer life for the engine.
Cylinder liners are of two types
Dry liners and wet liners. Let’s take the detail view.
Construction: The construction of a dry liner is shown in the figure. This liner is made in the shape of a barrel with a flange at the top which keeps it into position.
The entire outer surface of the liner bears against the casting of the cylinder block. Therefore, it is important to machine both inner and outer faces accurately.
The liner should not be too loose, otherwise, the heat dissipation becomes poor because of the absence of good contact with the cylinder block.
The figure shows a simple sketch of the wet liner. These liners will come in direct contact at their outer faces with the cooling water.
These liners don’t need to be machined precisely at the outer surface. They are machined precisely at the inner surfaces.
They resist corrosion when in constant contact with cool water. They are also coated with aluminum at their outer surfaces.
- At the top, the liner is provided with a flange which fits into the groove in the cylinder block.
- At the bottom of the liner is provided with a groove, generally three in number.
- The middle groove is left empty to drain any water that might leak from the top ring.
- And in the top and bottom ones are inserted packing ring, made of synthetic rubber.
Comparison of the dry and wet liner
- Dry liners may be provided either in the original design or even afterwards.
- The construction of the cylinder block very complicated. The cooling effect is poor.
- Accurate machining of dry liners for perfect contact with the cylinder casting is essential.
- It cannot be completed before fitting. It is not necessary to have a leak-proof joint.
- Wet liners have to be included in the original design. The construction of the cylinder block is simple.
- The liner will be in direct contact of cooling water and this improves the cooling effect.
- Not all lines need to be machined accurately. They can be completed before fitting.
- Between the cylinder block and wet liner, a leak-proof joint must be created.
Pitons are most important engine parts compared to others. The piston is a cylindrical, moving plug that moves in the cylinder.
It helps to convert pressure energy obtained by the combustion of fuel into useful mechanical power and it transfer this power to the crankshaft through the connecting rod.
- The highest position of the piston reaches in the cylinder is called the Top Dead Centre(TDC) and
- The lowest position it reaches is called the Bottom Dead Centre(BDC).
It is equipped with pistons ring approximately 3 to 5 which provide a good seal between piston and cylinder wall. The efficiency and economy of the engine primarily depend on the working of the piston.
Reading: Tile Shapes
The piston’s material is important.
- Cast iron,
- Aluminium alloy.
- Aluminium alloys are now widely used. It can either be cast or forged.
The piston must possess the following qualities
- Rigidly to withstand high pressure
- Light in weight, to reduce the reciprocating mass to perform at higher engine speed.
- Good heat conductivity.
- Operation is quieter.
The piston is usually small in diameter than the bore of the cylinder. The piston clearance refers to the space between the wall of the cylinder and its cylinder. This piston clearance provides a space for a layer of lubricant between the piston and cylinder wall to reduce friction.
Generally, piston clearance is
- 0.025mm to 0.100mm.
A proper clearance between the piston wall and the cylinder wall should be maintained.
- If the clearance is too small, there will be a loss of power from excessive friction, more wear, seizing of the piston in the cylinder.
- The piston slap can occur if the clearance is too low. Piston slap means sudden tilting of the cylinder as the piston moves down during the power stroke.
It prevents piston seizing due to high temperatures. It is impossible to turn the piston within the cylinder if there isn’t enough clearance.
Functions of piston
some of the important function of the piston as follows
- To transmit the power developed by fuel combustion to the crankshaft through the connecting rod.
- To seal the crankcase from high-pressure combustion gases.
- Piston serves as a support for the small end of the connecting rod.
- To capture the charge and push the exhaust gases out.
The cross-section of a piston is shown in the figure.
- The top of the piston is called the head or crown.
- Towards the top of the piston, a few grooves are cut to house the piston rings. Lands are the spaces between the grooves.
- The part of the piston below the ring is called Skirt is provided with bosses on the inside to support the piston pin (Gudgeon pin).
- The distance between the axis of the piston pin and the top of the piston crown is called compression height.
Type of pistons
The various types of pistons are classified depending on the shape, design, operation. The important types of the piston as follows.
- Cast Iron Pistons
- Forged pistons
- Cast Steel Piston
- BI-metal piston
- Two-piece piston
- Oil-cooled pistons
- Anodized piston
- Tinned pistons
Piston materials: Cast Iron, Aluminium, Lo-Ex Alloy, Invar, Steel alloy. Protective coating: Cadmium plating, Anodised pistons, Tinned pistons, Chromium plating.
Also, see all information about internal combustion engines (I.C. Engines)
9. Piston Rings
The piston rings are fitted into the grooves of the piston to maintain a good seal between the piston and the cylinder wall.
The number of piston rings used is about 2 to 4 compression rings and 1 to 2 oil control ring was used but in modern design the number if rings usually three out of which one is the oil control ring.
The function of piston rings
- To form a seal for the high pressures gases from the combustion chamber entering into the crankcase.
- The piston ring allows heat flow to be easily passed from the piston crown towards the cylinder walls.
- The piston ring helps reduce cylinder wear by ensuring that sufficient lubrication oil is maintained on the walls of the cylinder throughout its entire travel.
The figure shows the piston ring construction:
- The ring is generally cast individually and machined carefully so that when in the position it is able to exert uniform pressure against the cylinder walls.
- The end has a gap.
- The gap between the end of the piston ring and the piston is usually kept at 0.30 to 0.35mm.
- When the piston is in the cylinder, the gap is nearly closed.
The piston ring end gap may be
- Butt type
- Taper type
- Lap type
Material for piston rings
The material generally used for piston rings is
- fine-grained alloy cast iron containing silicon and manganese. It resists heat and wear.
Chromium plated rings are also used for the top ring, which is subjected to the highest working temperatures and the corrosive action of the combustion products.
Types of Piston Rings
Mainly there are two types of piston rings as follows.
- Compression rings: Fig shown a simple sketch of Compression rings. these rings effectively seal the compression pressure and the leakage of the combustion gasses. These rings are installed in the top grooves. They transfer heat from the piston onto the walls of the cylinder.
- Oil control rings: The Figure shows a simple sketch of oil control ring. The main purpose of the oil ring is to scrape the excess oil from the liner and return it back to the oil sump during the downward and upward movement of the piston. It stops oil from getting into the combustion chamber. One of two oil control rings is used in a piston. When two rings are used, one is placed above and the other below the gudgeonpin in the piston. Drain holes or slots are included on these rings. These slots allow scraped oil through the piston holes to reach the oil sump.
Read also: Piston Ring Maintenance – thegoneapp.com
10. Connecting Rod
Fig showed a connecting rod. It is placed between the crankshaft and piston.
The main function of the connecting rod is to convert the reciprocating motion of the piston into the rotary motion of the crankshaft.
It should be lightweight and strong enough for bending and stress.
- The connecting rod usually has I-beam cross-section and is made of alloy steel of duralumin by drop forging.
- It can also be made from malleable graphite C.I.
- The small end of the connecting rod has either a solid eye used to connect the piston by the piston pin.
- The big end of the connecting rod is always split is used to connect the crank pin of the crankshaft.
11. Piston Pin
The piston pin is also called wrist pin or gudgeon pin. It is used for connecting the small end of the connecting rod and the piston.
Construction: It is made hollow to reduce weight and it is made from case hardened steel.
Mainly there are three types of piston pins as follows.
- Set screw types piston pin.
- Semi-floating piston pin
- Fully floating piston pin
Fig (a) shown Set screw type piston pin, This pin is fastened to the piston to the piston by a SET SCREW such that the connecting rod end swivel has required by the combined reciprocating and rotary motion of the piston and crankshaft.
Fig (b) shown the Semi-floating piston pin, It is fastened to the connecting rod with a clamp screw.
Fig (c) shown Fully floating piston pin. The pin floats in both the piston bosses and the small end of connecting rod. Two circlips prevent the pin from coming into contact with the cylinder wall.
The crankshaft is the engine component from which the power is taken. It is one of the main power transmission sources in all engine parts.
The Crankshaft is the first part of the power transmission system in which the reciprocating motion of the piston is converted into the rotating motion with the help of connecting rod.
- The crankshaft is made of casting or forging of heat treated alloy steel and is machined.
- A crankshaft consists of crankpins, weds, balancing weight and main journals and oil holes.
- The big end of the connecting rod is connected to the crankpin of the crankshaft.
- Centre to centre distance between the crankpin and crankshaft is half of the piston displacement during the stroke.
- Thus one complete revolution of the crankshaft makes two strokes of the piston.
The parts of the crankshaft inside the main bearing are called main journals.
- On the opposite side, you will find balance weights. The crankshaft has oil passages that allow oil to flow from the main bearing to connecting rod bearings.
The front end of the crankshaft carries three devices that
- A gear that drives the camshaft,
- The vibration damper to control torsional vibration, and
- The fan belt pulley. This pulley drives an engine fan, water pump and generator with a V belt.
The rear end of the crankshaft carries flywheel. The flywheel helps to maintain the crankshaft at constant speed.
The main journal and oil seal are located at the rear. Oil return threads can be found in some engines. These return the lubricating fluid to the sump.
The crankshafts are generally of two types,
- In one piece type, all the parts are integral and are formed by drop forging and then machining.
- In build-up type, the crankpins and journals are fastened to the crank webs.
13. Cam Shaft
A camshaft is a shaft on which cams are mounted. A cam is a device that changes the rotary motion of the camshaft into the linear motion of the follower. A camshaft is responsible for the opening of the valves.
- A camshaft has a number of cams along the length, two cams for each cylinder, one to operate the inlet valve and the other the exhaust valve.
- Additionally, the camshaft includes an eccentric to control the fuel pump as well as a gear to drive both the ignition distributor or oil pump.
- The camshaft is driven by the crankshaft. The camshaft gear is twice as long as the crankshaft gear.
- Camshaft made from forged alloy steel.
This gives 1:2 gear ratio, the camshaft turns at half the speed of the crankshaft.
- Thus, every two revolutions of the crankshaft produce one revolution o the camshaft and one opening and closing of each valve, in the four-cylinder engine.
- Thus there is correct opening and closing of the valves takes in relation to the position of the piston in the cylinder.
There are three types of camshaft drive mechanism as follows,
- Gear drive.
- Chain drive.
- Belt drive.
The flywheel used in a transmission system of a vehicle.
- A flywheel is a heavy steel wheel attached to the rear end of the crankshaft.
- The size of the flywheel depends upon the number of cylinders and the construction of the engine.
- During the power stroke, the engine tends to speed up and during the other strokes, it tends to slow down.
- The inertia of the flywheel tends to keep the running of the crankshaft at a constant speed. This ensures that the engine speed remains constant.
15. Engine Valves
Engine valves are essential to control the timing of air-fuel mixture entry into the cylinder and combustion products out of the cylinders.
- These are located at the inlet and outlet opening of the engine cylinder.
- When the valve seats are closed, they fit onto the valve seats.
There are three types of engine valves as follows,
- Poppet valve
- Sleeve valve
- Rotary valve
15.1 Poppet valve
This is the most widely used valve in automobile engines. The poppet valve is given the name because of its motion of popping up and down.
Its It is easy to construct. This is also called a mushroom valve, because of its shape.
- It consists of a head and a stem. The valve face usually with an angle of 30° to 45° is ground perfectly, since it has to match with the valve seat for perfect sealing.
- The stem has a spring retainer lock groove and the stem end is in contact with cam for up and down movements of the valve.
15.2 Sleeve Valve
The sleeve valve as the name implies, that it is a tube or sleeve kept between the cylinder wall and the piston.
- The inner surface of the sleeve actually forms the inner cylinder barrel in which the piston slides.
The sleeve is in continuous motion and admits and drives out the gases by virtue of the periodic coincidence of port cut in the sleeve with ports formed through the main cylinder casting.
- Simple in construction.
- Sleeve valves can be operated quietly.
- There is noise because there is no noise-making parts like valve cams, racker arm, tappets valves etc.,
- The tendency of detonation is less.
- The valve is in direct contact with water jackets, so cooling is very efficient.
- High oil consumption for lubrication as a larger area of sleeve surface to be lubricated.
- Cleaning of the ports and the valve is complicated.
15.3 Rotary valve
Fig showed a simple sketch of Rotary Valve. There are many types of rotary valves. The figure shows the disc-type rotary valve. It consists of a rotating disc which has a port. It rotates and communicates with the exhaust and inlet manifolds.
- Rotary valves are simple in construction.
- These valves can be manufactured at lower costs.
- These valves are ideal for high-speed engines.
- The vibrations and stresses are lower than those of poppet or sleeve vales.
- They operate smoothly and make no noise.
- It is difficulties in pressure sealing between the rotary disc and cylinder.
- It is hard to provide effective valve lubrication.
Materials for valves
The materials used for inlet and exhaust valve are generally different because of the different operating conditions to which valves are subjected.
Inlet valves are made of silico-chrome steel. Add molybdenum to the silico-chrome to make exhaust valves.
Astenite steel and precipitation-hardening steel are the most popular materials for exhaust valves.
In petrol engines, the carburettor control both air and fuel supply to the engine cylinder under speed and load conditions.
They vary the supply of air-fuel mixture to meet the given condition. In the diesel engine, the governor keeps the engine’s speed within a set limit.
- The main functions of a governor are to regulate the supply of fuel through some mechanism so that the engine speed remains within its range.
- On increased load, the engine speed decreases.
- The engine speed rises when the load decreases.
Without a governor the engine speed increases with lighter loads. The dynamic stresses on the engine parts can cause engine damage.
A governor is an engine speed setting that allows for more fuel to be injected to increase engine power.
Governor, in this case, operates the mechanism to reduce the supply of fuel in the engine. It is important to maintain the engine speed within set limits.
Types of Governor:
- Mechanical Governor or Torque control Governor or Centrifugal governor.
- Pneumatic Governor.
- Hydraulic governor.
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