For more than a hundred years, internal combustion engines have been used as the power plants of most machines and mechanisms. At the beginning of the 20th century, they replaced a steam engine of external combustion. ICE is now the most economical and efficient among other engines. Let's look at the design of an internal combustion engine.
History of creation
The history of these units began about 300 years ago. It was then that Leonardo Da Vinci developed the first drawing of a primitive engine. The development of this unit gave impetus to the assembly, testing and continuous improvement of ICE.
In 1861, according to the drawings that Da Vinci left the world, they created the first two-stroke engine. At that time, no one had thought that all cars and other equipment would be equipped with such installations, although steam units on railway equipment were then used.
The first to use ICE in cars was Henry Ford. He was the first to write a book about the design and operation of internal combustion engines. Ford was the first to calculate the efficiency of these engines.
ICE classification
In the process of development, the construction of an internal combustion engine became more complicated. His appointment at the same time remained the same. There are several main types of internal combustion engines that are most effective today.
The first in terms of efficiency and economy are piston units. In these units, the energy generated from the combustion of the fuel mixture is converted into motion through a system of connecting rods and crankshaft.
The general arrangement of a carbureted internal combustion engine is no different from other engines. But the combustible mixture is prepared directly in the carburetor. Injection is carried out into a common collector, from where, under the influence of vacuum, the mixture enters the cylinders, where it is then ignited by an electric discharge on a candle.
An injection engine differs from a carburetor in that fuel is supplied to each cylinder directly through separate nozzles. Then, after gasoline is mixed with air, the fuel is ignited by a spark of a candle.
Diesel engine is different from gasoline. Consider briefly the design of a diesel internal combustion engine. No candles are used here for ignition. This fuel ignites under high pressure. As a result, the diesel heats up. The temperature exceeds the combustion temperature. Injection is carried out by means of nozzles.
To the internal combustion engine include rotary piston engines. In these units, thermal energy from fuel combustion acts on the rotor. It has a special shape and special profile. The trajectory of the rotor is planetary (the element is inside a special chamber). The rotor simultaneously performs a huge number of functions - this is gas distribution, the function of the crankshaft and piston.
There are gas turbine internal combustion engines. In these units, thermal energy is converted through a rotor with wedge-shaped blades. Then these mechanisms make the turbine spin.
The most reliable, low-maintenance and economical piston engines are considered. Rotary almost never used in mass automotive technology. Now models of cars equipped with rotary piston engines are produced only by the Japanese Mazda. Chrysler produced experimental cars with gas turbine engines in the 60s, and after that no automaker returned to these units. In the Soviet Union, some models of tanks and landing ships were briefly equipped with gas turbine engines. But then it was decided to abandon such power units. That is why we are considering the design of an internal combustion engine - they are the most popular and effective.
ICE device
In the motor housing several systems are combined. This is a cylinder block, in which the very combustion chambers are located. In the latter, the fuel mixture burns. Also, the engine consists of a crank mechanism designed to convert the energy of movement of the pistons into the rotation of the crankshaft. In the case of the power unit there is also a gas distribution mechanism. Its task is to ensure the timely opening and closing of the intake and exhaust valves. The engine will not be able to work without an injection system, ignition, and also without an exhaust system.
When starting the power unit, a mixture of fuel and air is supplied to the cylinders through the open intake valves. Then it ignites from an electric discharge on the spark plug. When the mixture ignites and the gases begin to expand, the pressure on the piston will increase. The latter will be set in motion and cause the crankshaft to rotate.
The design and operation of the internal combustion engine are such that the engine operates in certain cycles. These cycles are constantly repeated at high frequency. This ensures continuous rotation of the crankshaft.
The principle of operation of two-stroke ICE
When the engine starts, the piston, which is driven by the rotation of the crankshaft, starts to move. When it reaches its lowest point and begins to move upward, fuel is supplied to the cylinder.
When moving upward, the piston compresses the mixture. When it reaches top dead center, the candle ignites the mixture due to an electric discharge. Gases instantly expand and push the piston down.
Then the exhaust valve of the cylinder opens and the combustion products exit the cylinders into the exhaust system. Then, again reaching the bottom point, the piston will begin to move up. The crankshaft will make one revolution.
When a new piston movement begins, the intake valves will open again and the fuel mixture will be supplied. It will take up the entire volume occupied by the combustion products, and the cycle will be repeated again. Due to the fact that the pistons in such engines operate in only two cycles, fewer movements are made, in contrast to the four-stroke ICE. Friction loss of parts is reduced. But these motors get hotter.
In two-stroke power units, the piston also plays the role of a gas distribution mechanism. During the movement, the openings for the intake of the fuel mixture and the release of exhaust gases open and close. The worst gas exchange compared to four-stroke engines is the main disadvantage of such engines. At the time of exhaust gas production, power is significantly lost.
At the moment, two-stroke engines are used in mopeds, scooters, boats, gasoline saws and other low-power equipment.
Four stroke
The device of an internal combustion engine of this type is slightly different from a two-stroke one. The principle of operation is also a little different. There are four clock cycles per rotation of the crankshaft .
The first stroke is the supply of a combustible mixture to the engine cylinder. The motor, under the influence of vacuum, sucks the mixture into the cylinder. The piston in the cylinder goes down at this moment. The inlet valve is open, and atomized gasoline enters the combustion chamber with air.
Next is the compression beat. The inlet valve closes and the piston moves up. In this case, the mixture in the cylinder is significantly compressed. Due to pressure, the mixture heats up. Pressure increases concentration.
This is followed by the third working cycle. When the piston almost reaches its upper position, the ignition system is triggered. A spark jumps on the candle, and the mixture ignites. Due to the instant expansion of gases and the propagation of explosion energy, the piston moves downward under pressure. This cycle in the operation of the four-stroke motor is the main one. The other three measures do not affect the creation of the work and are auxiliary.
At the fourth measure, the release phase begins. When the piston reaches the bottom of the combustion chamber, the exhaust valve opens and the exhaust gases exit first into the exhaust system, and then into the atmosphere.
Here is such a device and the principle of operation of a four-stroke internal combustion engine, which is installed under the hoods of most cars.
Auxiliary systems
We examined the design of an internal combustion engine. But any motor could not work if it were not equipped with additional systems. We will talk about them below.
Ignition
This system is part of electrical equipment. It is designed to form sparks that ignite the fuel mixture.
The system includes a battery and a generator, an ignition switch, a coil, as well as a special device - an ignition distributor.
Intake system
It is necessary so that air enters the motor without any interruptions. Oxygen is needed to form a mixture. Gas alone will not burn. It should be noted that in the carburetors the inlet is only a filter and air ducts. The intake system of modern cars is more complex. It includes an air intake in the form of nozzles, a filter, a throttle valve, as well as an intake manifold.
Supply system
From the principle of the construction of an internal combustion engine, we know that the motor needs to burn something. This is gasoline or diesel. The power system provides fuel supply during the operation of the motor.
In the most primitive case, this system consists of a tank, as well as a fuel line, filter and pump, which provide fuel to the carburetor. In injection cars, the power system is controlled by an ECU.
Lubrication system
The lubrication system includes an oil pump, a sump, a filter for cleaning oil. Diesel and powerful gasoline power units also have a radiator for cleaning grease. The pump is driven by a crankshaft.
Conclusion
This is what an internal combustion engine is. We examined the device and its operating principle, and now it is clear how a car, chainsaw or diesel generator works.