THE CAR ENGINE FEATURES
Most cars are powered by a piston engine known as the internal combustion (IC) engine that burns a mixture of petrol and air. The mixture is burned in a combustion chamber within a cylinder above a piston.
When it burns, the mixture expands rapidly and the pressure that this exerts on the top of the piston forces it down the cylinder. The underside of the piston is connected by a rod known as a connecting to a crankshaft and the arrangement of the two allows the downward path of the piston to be transformed into rotary movement of the shaft from the reciprocating motion to rotating motion. Based on the configurations of the IC engine, the power in the crankshaft is transmitted to the wheels that drive the car through the clutch or torque converter, gearbox, and final drive.
Inlet and exhaust valves at the top of the cylinder control the entry of the petrol/air mixture and the exit of the burned gases into the exhaust system. The valves are operated by eccentric lobes on a camshaft which is driven from the crankshaft. The mixture is ignited in the combustion chamber by a spark plug. The high-voltage or high tension current necessary to produce a spark is generated within a separate ignition system and usually fed to each cylinder as required by a distributor, normally driven by the camshaft.
HOW INTERNAL COMBUSTION ENGINES START THEIR COMBUSTION OF FUEL
To start the engine, it must be rotated. This is done electrically by a starter motor which rotates the crankshaft, usually by engaging a small pinion with the gear teeth around the outer edge of a flywheel, bolted to the end of the crankshaft. Besides providing a means of starting the engine, the flywheel smooths out the power pulses from the pistons and allow the crankshaft to turn relatively smooth.
Whenever the crankshaft is being rotated by the starter, the up and down movement of the pistons sucks mixture of air and fuel into the cylinders (combustion chamber) repeatedly until the combustion chamber is filled with enough volume of air-fuel mixture such that when the ignition starter is switched off, the sparks from the plugs will ignite the mixture in the combustion chamber in that case, combustion begins immediately causing the engine to start running.
COMPONENTS MAKING THE IC ENGINES LAST LONGER AND OPERATE WITHOUT FAILURE
To ensure steady operation and prolonged engine life, the IC engines are equipped with the cooling system and lubricating system.
The cooling system of IC engines could be air cooling or water cooling. The air cooling method will not use water inside the engine rather the external surroundings of the combustion chambers are made to have fins of uniformly spaced metal to allow for easy dispersing of heat generated from the combustions to the environment and the atmospheric temperature of the surrounding will help to keep the combustion chamber at moderate temperature.
The water cooling method had been the most widely used for the car engines and seems to be the most effective for car engines, in such method, holes of water channel are created inside the body of the engine especially within the combustion chamber such that the two exit ports of the water channels will be fixed to the inlet and outlet ports of a radiator such that when the engine is in operation the water will be re-cycling from the radiator into the engine continuously while an external fan will help in cooling the hot water coming from the engine before it can go back again from the inlet port.
The lubrication system works almost similar to the cooling system but its major function is restricted to the interior of the engine only. While water and air cool the engine, the lubrication system makes the engine to run smoothly with less wear and tear. Though the lubrication system does offer some level of engine cooling, its basic function is to help reduce the wear and tear of the moving engine parts.
THE COMPONENTS THAT TRANSMIT THE POWER FROM THE IC ENGINES
The components that transmit the power are the pistons, connecting rods, and crankshaft and they are hidden inside the cylinder block, and the outside of the block and cylinder head carries a number of vital ancillary components.
The components include; the inlet and exhaust manifolds, which carry fuel and air to the cylinders and pipe exhaust gas out, carburetor, distributor, starter motor, generator and usually the petrol pump. The positions of these components vary a little depending on the layout of the engine. Some of the outside components are hard to find. The carburetor is usually beneath a big air filter and the exhaust manifold may be half buried in a heat box that directs warm air to the carburetor.
Also, there will be a number of small diameter hoses. Besides taking water to and from the interior heater, hoses often feed water from the cylinder block to a jacket around the inlet manifold where warmth helps to vaporize the mixture. They also pipe crankcase fumes to the inlet manifold.
However, at the external parts of the engine, the ends of the crankshaft is usually connected to flywheel, pulley, or any drive mechanism where the power can be put into use for any purpose it is meant for. In the case of the car engine, the power will be directed into the driving mechanism of the car wheels.
THE HEAVY-METAL PARTS OF THE IC ENGINES
Because of substantial temperatures and forces generated within the IC engine, components in direct contact with the loads must be extremely rigid and very strong to withstand the severe environment in the engine. When it comes to parts and assemblies in the IC engine, three major assemblies can be found for the mentioned purpose and they are:
THE CYLINDER HEAD
The cylinder head contains combustion chambers, the valves (usually two in each cylinder), spark plugs, the springs that close the valves and the valve gear that opens them and the inlet and exhaust ports.
THE CYLINDER BLOCK
The cylinder block contains cylinders and houses the crankshaft, pistons and connecting rods.it may also carry the camshaft but on some engines, it can be mounted above the cylinder head and where this is done, the engine is known as an overhead camshaft engine (OHC.). in water-cooled engines, both the cylinder block and cylinder head contain passages through which cooling water circulates.
THE CRANKSHAFT ASSEMBLY
The crankshaft assembly includes the piston, connecting rods, and the crankshaft. The shaft is carried in main bearings mounted between the cylinders at the bottom of the cylinder block. At one end of the crankshaft is the flywheel. At the base of the engine, a pressed steel or cast aluminum sump provides a reservoir for lubricating oil. At the top, a cover keeps in the oil that lubricates the valves gear and, on modern engines, provides a seal against atmospheric air.
