Currently, the internal combustion engine is the main type of automobile engine. An internal combustion engine (abbreviated as ICE) is a thermal machine that converts the chemical energy of fuel into mechanical work. In some situations, its breakage is a reason to call mississauga junk car removal.
There are the following basic types of internal combustion engines:
reciprocating internal combustion engine;
rotary-piston internal combustion engine;
Gas-turbine combustion engine.
Of the presented types of engines, the most common is a piston internal combustion engine, so the device and principle of operation are considered on its example.
The advantages of the reciprocating internal combustion engine, which ensured its wide application, are:
universality (combination with different consumers);
possibility of quick start-up;
At the same time, internal combustion engines have a number of significant drawbacks, which include:
high noise level;
high crankshaft rotation speed;
toxicity of exhaust gases;
low service life;
Depending on the type of fuel used, the following piston internal combustion engines are distinguished:
Alternative fuels used in internal combustion engines are natural gas, alcoholic fuels – methanol and ethanol, hydrogen.
Hydrogen engine is environmentally promising, because it does not create harmful emissions. Along with the internal combustion engine hydrogen is used to create electrical energy in the fuel cells of cars.
A reciprocating internal combustion engine has the following general structure:
ignition system (gasoline engines);
The engine casing combines the cylinder block and cylinder head. The crank mechanism converts the reciprocating motion of the piston into the rotary motion of the crankshaft. The timing mechanism ensures the timely supply of air or fuel-air mixture into the cylinders and the exhaust of exhaust gases.
The intake system is designed to supply air to the engine. The fuel system feeds fuel to the engine. These systems work together to produce the fuel-air mixture. The fuel system is based on the injection system.
The ignition system carries out the forced ignition of the fuel-air mixture in gasoline engines. In diesel engines, the mixture is self-ignited.
The lubrication system has the function of reducing friction between the mating parts of the engine. The cooling system cools engine parts that are heated as a result of operation. The exhaust system has an important function in dissipating exhaust gases from the engine cylinders, reducing noise and toxicity.
The engine management system electronically controls the combustion engine systems.
The principle of operation of the internal combustion engine is based on the thermal expansion of gases, which occurs during combustion of the fuel-air mixture and ensures the movement of the piston in the cylinder.
Operation of the piston internal combustion engine is cyclic. Each operating cycle takes two revolutions of the crankshaft and includes four strokes (four-stroke engine):
During the intake and stroke cycles, the piston moves downward, while the compression and exhaust cycles move upward. The operating cycles in each of the engine cylinders do not coincide in phase, which achieves the uniformity of the internal combustion engine. In some combustion engine designs, the work cycle is realized in two strokes – compression and stroke (two-stroke engine).
During the intake stroke, the intake and fuel systems ensure the formation of the fuel-air mixture. Depending on the design, the mixture is generated in the intake manifold (central and distributed injection for gasoline engines) or directly in the combustion chamber (direct injection for gasoline engines, injection for diesel engines). When the intake valves of the timing gear open, air or fuel-air mixture is fed into the combustion chamber due to the vacuum resulting from the downward movement of the piston.
During the compression stroke, the intake valves close and the fuel-air mixture is compressed in the engine cylinders.
The stroke stroke is accompanied by the ignition of the fuel-air mixture (forced or self-ignition). As a result of the combustion, a large amount of gas is produced, which presses on the piston and makes it move downward. The movement of the piston through the crank mechanism is converted into a rotary movement of the crankshaft, which is then used to move the vehicle.
During the exhaust stroke the exhaust valves of the timing gear open and the exhaust gases are removed from the cylinders into the exhaust system, where they are cleaned, cooled and noise is reduced. The gases are then discharged into the atmosphere.
The considered principle of operation of the internal combustion engine allows us to understand why the internal combustion engine has a small efficiency of about 40%. At a particular moment of time, as a rule, only one cylinder performs useful work, the rest – providing strokes: intake, compression, exhaust.