The device of the internal combustion engine

For a century, an internal combustion engine has been used in motorcycles, cars and trucks. Until now, it remains the most economical type of motor. But for many, the principle of operation and the design of the internal combustion engine remains incomprehensible. Let's try to understand the basic subtleties and specifics of the structure of the motor.

📌Definition and general features

A key feature of any internal combustion engine is the ignition of the combustible mixture directly in its working chamber, and not in external media. At the time of fuel combustion, the resulting thermal energy provokes the operation of the mechanical components of the motor.

📌Creating history

Before the advent of internal combustion engines, self-propelled vehicles were equipped with external combustion engines. Such units worked from the vapor pressure generated as a result of heating water in a separate tank.

The design of such engines was dimensional and ineffective - in addition to the large weight of the installation, to overcome long distances, transport also had to carry a decent supply of fuel (coal or firewood).

Due to this shortcoming, engineers and inventors tried to solve an important issue: how to combine fuel with the body of the power unit. By removing from the system such elements as a boiler, water tank, condenser, evaporator, pump, etc. it was possible to significantly reduce the weight of the motor.

The creation of an internal combustion engine in the usual form for a modern motorist took place gradually. Here are the main milestones that led to the emergence of a modern ICE:

• 1791 John Barber invents a gas turbine, which operated on the basis of the process of "distillation" of oil, coal and wood in retorts. The resulting gas along with air was pumped by the compressor into the combustion chamber. The resulting hot gas was fed under pressure to the impeller impeller and rotated it.
• 1794 Robert Street patents a liquid fuel engine.
• 1799 Phillip Lebon as a result of pyrolysis of oil receives luminous gas. In 1801, proposes to use it as fuel for gas engines.
• 1807 Francois Isaac de Rivaz - patent on "the use of explosive materials as a source of energy in engines." Based on the development creates a "self-propelled crew."
• 1860 Etienne Lenoir for the first time embodied the reality of his early inventions by creating a workable motor powered by a mixture of light gas and air. The mechanism was driven by a spark from an external power source. The invention was used on boats, but was not installed on self-propelled machines.
• 1861 Alphonse Bo De Roche reveals the importance of fuel compression before ignition, which served to create a theory of the four-stroke engine (suction, compression, combustion with expansion and release).
• 1877 Nikolaus Otto creates the first four-stroke engine with a capacity of 12 hp
• 1879 Karl Benz patented a two-stroke engine.
• 1880s. Ogneslav Kostrovich, Wilhelm Maybach and Gottlieb Daimler are simultaneously developing carburetor modifications of the internal combustion engine, preparing them for serial production.

In addition to gas-fueled engines, the Trinkler Motor appeared in 1899. This invention is another type of ICE (non-compressor high-pressure oil engine), operating on the principle of the invention of Rudolf Diesel. Over the years, power units, both gasoline and diesel, have been improved, which increased their efficiency.

📌Types of internal combustion engines

By the type of design and the specifics of the operation of the internal combustion engine are classified according to several criteria:

• By the type of fuel used - diesel, gasoline, gas.
• According to the principle of cooling - liquid and air.
• Depending on the location of the cylinders - in-line and V-shaped.
• By the method of preparing the fuel mixture - carburetor, gas and injection (mixtures are formed in the outer part of the internal combustion engine) and diesel (in the inner part).
• According to the principle of ignition of the fuel mixture - with forced ignition and self-ignition (typical for diesel units).

Engines are also distinguished by specific design and operational efficiency:

• Piston, in which the working chamber is localized in the cylinders. It is worth considering that such ICEs are divided into several subspecies:
  • carburetor (the carburetor is responsible for creating an enriched working mixture);
  • injection (mixture flows directly into the intake manifold through nozzles);
  • diesel (ignition of the mixture occurs due to the creation of high pressure inside the chamber).
  • Rotary-piston, characterized by the conversion of thermal energy into mechanical energy due to the rotation of the rotor along with the profile. The work of the rotor, whose movement in shape resembles an 8-ku, completely replaces the functions of pistons, timing and crankshaft.
  • Gas turbine, in which the motor is driven by thermal energy obtained by rotating the rotor with blades resembling a blade in shape. He drives the turbine shaft.

The theory, at first glance, seems understandable. Now consider the main components of the powertrain.

📌 ICE device

The housing design includes such components:

• cylinder block;
• crank mechanism;
• gas distribution mechanism;
• systems for supplying and igniting a combustible mixture and removing combustion products (exhaust gases).

To understand the location of each component, consider the structure of the motor:

The number 6 indicates the place where the cylinder is located. It is one of the key components of ICE. Inside the cylinder there is a piston, indicated by the number 7. It is fastened with a connecting rod and crankshaft (indicated on the diagram by numbers 9 and 12, respectively). Moving the piston inside the cylinder up and down provokes the formation of rotational movements of the crankshaft. A flywheel is shown at the end of the crank, which is shown in the diagram under the number 10. It is necessary for uniform rotation of the shaft. The upper part of the cylinder is equipped with a tight head having valves for the intake of the mixture and the release of exhaust gases. They are shown under the number 5.

The opening of the valves becomes possible due to the camshaft cams, designated number 14, or rather, its transmission elements (number 15). The rotation of the camshaft is provided by the crankshaft gears, indicated by the number 13. When the piston moves freely in the cylinder, it is able to take two extreme positions.

To ensure the normal operation of the internal combustion engine can only a uniform supply of the fuel mixture at the right time. To reduce the engine’s operating costs for heat removal and to prevent premature wear of the moving components, they are lubricated with oil.

📌The principle of the internal combustion engine

Modern ICEs are powered by flammable fuel inside the cylinders and the energy that appeared as a result of this. A mixture of gasoline and air is supplied through the inlet valve (in many engines, two per cylinder). In the same place, it ignites due to the spark that forms spark plug. At the time of the mini-explosion, the gases in the working chamber expand, creating pressure. It drives a piston attached to a cshm.

Diesels operate on a similar principle, only the combustion process is initiated somewhat differently. Initially, the air in the cylinder is compressed, which causes it to heat up. Before the piston reaches TDC in the compression stroke, the nozzle sprays fuel. Because of the hot air, the fuel ignites on its own without a spark. Further, the process is identical to the gasoline engine modification.

KShM converts reciprocating movements of the piston group into rotation crankshaft. Torque goes to the flywheel, then to manual or automatic gearbox and finally - on the drive wheels.

The process while the piston is moving up or down is called a beat. All measures until they are repeated are called a cycle.

One cycle includes the process of absorption, compression, ignition along with the expansion of the resulting gases, exhaust.

There are two modifications of motors:

1. In a push-pull cycle, the crankshaft turns once, and the piston goes down and goes up.
2. In a four-stroke cycle, the crankshaft will crank twice, and the piston will make four complete movements - it will lower, rise, lower, rise.

📌Working principle of two-stroke engine

When the driver starts the engine, the starter drives the flywheel, the crankshaft rotates, the crankshaft moves the piston. When it reaches the BDC and begins to rise, the working chamber is already filled with a combustible mixture.

In the TDC of the piston, it ignites, and moves it down. Then ventilation occurs - the exhaust gases are displaced by a new portion of the working combustible mixture. Purge can occur in different ways depending on the motor device. One of the modifications involves filling the sub-piston space with a fuel-air mixture when it rises, and when the piston drops, it is squeezed out into the working chamber of the cylinder, displacing combustion products.

In such modifications of the engines there is no valve timing system. The piston itself opens / closes the inlet / outlet.

Such motors are used in low-power technology, because gas exchange in them occurs due to the replacement of exhaust gases with another portion of the air-fuel mixture. Since the working mixture is partially removed along with the exhaust, this modification is characterized by increased fuel consumption and lower power compared to four-stroke counterparts.

One of the advantages of such internal combustion engines is less friction in one cycle, but at the same time they heat up more strongly.

📌Working principle of a four-stroke engine

Most cars and other motor vehicles are equipped with four-stroke engines. A gas distribution mechanism is used to supply the working mixture and exhaust gas. It is driven through a timing drive connected to a crankshaft pulley by a belt, chain or gear transmission.

Rotating camshaft raises / lowers the intake / exhaust valves located above the cylinder. This mechanism provides synchronized opening of the corresponding valves for supplying a combustible mixture and exhaust gas.

In such engines, the cycle occurs as follows (for example, gasoline ICE):

1. At the time of starting the engine, the starter cranks the flywheel, which drives the crankshaft. The inlet valve opens. A crank mechanism lowers the piston, creating a vacuum in the cylinder. There is a suction stroke of the air-fuel mixture.
2. Moving from bottom dead center upward, the piston compresses the combustible mixture. This is the second measure - compression.
3. When the piston is at top dead center, the spark creates a spark that ignites the mixture. Due to the explosion, gas expansion occurs. Excess pressure in the cylinder moves the piston down. This is the third step - ignition and expansion (or working stroke).
4. A rotating crankshaft moves the piston up. At this point, the camshaft opens the exhaust valve through which the rising piston displaces the exhaust gases. This is the fourth measure - release.

📌Auxiliary systems of the internal combustion engine

No modern internal combustion engine is capable of working independently. This is so because the fuel must be delivered from the gas tank to the engine, it must be ignited at the right time, and so that the engine does not "suffocate" from the exhaust gases, they must be removed on time.

Rotating parts need constant lubrication. Due to the elevated temperatures generated during combustion, the engine must be cooled. These accompanying processes are not provided by the motor itself, so the internal combustion engine works together with auxiliary systems.

📌Ignition system

This auxiliary system is designed for timely ignition of a combustible mixture with the corresponding piston position (TDC in compression stroke). It is used on gasoline internal combustion engines and consists of the following elements:

• Power supply. When the motor is in a calm state, this function is performed by the battery (how to start a car, if the battery is dead, read separate article) After starting the engine, it acts as an energy source generator.
• Egnition lock. A device that closes an electrical circuit to power it from a power source.
• Storage device. Most gasoline cars have an ignition coil. There are also models in which there are several such elements - one on each spark plug. They convert the low voltage coming from the battery into a high voltage current, which is necessary to create a high-quality spark.
• Distributor-breaker ignition. In carburetor cars, this is a distributor; in most others, this process is controlled by an ECU. Such devices distribute electrical pulses to the respective spark plugs.

📌Introduction system

To create a combustion process, a combination of three factors is necessary: ​​fuel, oxygen and an ignition source. If applying an electric discharge is the task of the ignition system, then the intake system provides oxygen to the engine so that the fuel can ignite.

This system consists of:

• Air intake - a pipe through which clean air is drawn. The admission process depends on the engine modification. In atmospheric engines, air is sucked in by creating a vacuum in the cylinder. In turbocharged models, this process is enhanced by the rotation of the supercharger blades, which increases the power of the motor.
• The air filter is designed to clean the flow of dust and small particles.
• Throttle - a valve that controls the amount of air entering the motor. It is regulated either by pressing the accelerator pedal, or by the electronics of the control unit.
• Intake manifold - a system of pipes connected to one common pipe. In the injection engine, a throttle valve is installed on top and for each cylinder along the fuel nozzle. In carburetor versions, a carburetor is installed on the intake manifold, in which air is mixed with gasoline.

In addition to air, fuel must also be supplied to the cylinders. For this purpose, a fuel system consisting of:

• fuel tank;
• fuel line - hoses and tubes through which gas or diesel fuel moves from the tank to the engine;
• carburetor or injector (nozzle systems spraying fuel);
• fuel pumppumping fuel from the tank to a carburetor or other device for mixing fuel and air;
• a fuel filter that cleans gasoline or diesel fuel from debris.

Today, there are many modifications of engines in which the working mixture is fed into the cylinders by various methods. Among these systems there are:

• single injection (carburetor principle, only with nozzle);
• distributed injection (for each cylinder a separate nozzle is installed, the air-fuel mixture is formed in the intake manifold channel);
• direct injection (nozzle spraying the working mixture directly into the cylinder);
• combined injection (combines the principle of direct and distributed injection)

📌Lubrication system

All friction surfaces of metal parts must be lubricated to cool and reduce their wear. To provide such protection, the motor is equipped with a lubrication system. It also protects metal parts from oxidation and removes carbon deposits. The lubrication system consists of:

• the oil pan - the reservoir in which the engine oil is located;
• an oil pump that creates pressure, due to which lubricant enters all components of the motor;
• an oil filter that traps any particles resulting from the operation of the motor;
• some vehicles are equipped with an oil cooler to further cool the motor lubrication.

📌Exhaust system

A high-quality exhaust system ensures the removal of exhaust gases from the working chambers of the cylinders. Modern cars are equipped with an exhaust system, which includes the following elements:

• exhaust manifold in which the vibrations of the hot exhaust gases are damped;
• a receiving pipe into which the exhaust gases come from the collector (like an exhaust manifold is made of heat-resistant metal);
• a catalyst that cleans exhaust gases from harmful elements, which allows the vehicle to comply with environmental standards;
• resonator - a capacity slightly smaller than the main muffler, designed to reduce exhaust speed;
• main silencer, inside which there are partitions that change the direction of the exhaust gases to reduce their speed and noise.

📌Cooling system

This additional system allows the motor to work without overheating. She supports engine operating temperaturewhile it is wound up. So that this indicator does not exceed critical boundaries even when the machine is standing, the system consists of the following parts:

• cooling radiatorconsisting of tubes and plates designed for quick heat exchange between the coolant and the ambient air;
• a fan that provides a larger flow of air, for example, if the car is in a traffic jam and the radiator is not sufficiently blown;
• a water pump, which ensures the circulation of the coolant that removes heat from the hot walls of the cylinder block;
• thermostat - a valve that opens after the engine warms up to operating temperature (before its operation, the coolant circulates in a small circle, and when it opens, the fluid moves through the radiator).

The synchronous operation of each auxiliary system ensures the smooth operation of the internal combustion engine.

📌 Engine Cycles

A cycle means actions that are repeated in a single cylinder. The four-stroke motor is equipped with a mechanism that triggers each of these cycles.

In the internal combustion engine, the piston performs reciprocating movements (up / down) along the cylinder. The connecting rod and the crank attached to it convert this energy into rotation. During one action - when the piston reaches from the lowest point to the top and back - the crankshaft makes one revolution around its axis.

In order for this process to occur constantly, an air-fuel mixture must enter the cylinder, it must be compressed and ignited in it, and combustion products must be removed. Each of these processes takes place in one crankshaft revolution. These actions are called bars. There are four of them in a four-stroke:

1. Intake or suction. At this stroke, an air-fuel mixture is sucked into the cylinder cavity. It enters through an open intake valve. Depending on the type of fuel system, gasoline is mixed with air in the intake manifold or directly in the cylinder, such as in diesel engines;
2. Compression. At this point, both the intake and exhaust valves are closed. The piston moves up due to cranking of the crankshaft, and it rotates due to performing other strokes in adjacent cylinders. In a gasoline engine, VTS is compressed to several atmospheres (10-11), and in a diesel engine - more than 20 atm;
3. Working stroke. At the moment when the piston stops at the very top, the compressed mixture is ignited using a spark from a spark plug. In a diesel engine, this process is slightly different. In it, the air is compressed so much that its temperature jumps to a value at which the diesel fuel ignites on its own. As soon as an explosion of a mixture of fuel and air occurs, the released energy has nowhere to go, and it moves the piston down;
4. Combustion products release. In order to fill the chamber with a fresh portion of the combustible mixture, the gases formed as a result of ignition must be removed. This happens in the next stroke when the piston goes up. At this moment, the outlet valve opens. When the piston reaches top dead center, the cycle (or set of strokes) in a separate cylinder is closed, and the process is repeated.

📌Advantages and disadvantages of ICE

To date, the best engine option for motor vehicles is ICE. Among the advantages of such units can be identified:

• ease of repair;
• profitability for long trips (depends on its volume);
• large working resource;
• accessibility for a middle-income motorist.

An ideal motor has not yet been created, so these units have some disadvantages:

• the more complex the unit and related systems, the more expensive their maintenance (example - EcoBoost motors);
• requires fine tuning of the fuel supply system, ignition distribution and other systems, which requires certain skills, otherwise the engine will not work efficiently (or will not start at all);
• more weight (compared to electric motors);
• wear of the crank mechanism.

Despite equipping many vehicles with other types of engines ("clean" cars powered by electric traction), ICEs will remain competitive due to their availability for a long time to come. Hybrid and electric versions of the car are gaining popularity, however, due to the high cost of such vehicles and the cost of their maintenance, they are not yet available to the average motorist.

Common questions:

What is an internal combustion engine? This is a kind of power units, where a closed combustion chamber is provided in the design, in which thermal energy is generated (due to the ignition of the fuel-air mixture) and converted into mechanical energy.

Who invented the internal combustion engine? A sample of the world's first internal combustion engine was discovered by the French inventor Etven Lenoir in 1860. The first four-stroke internal combustion engine, according to the scheme of which absolutely all power units work, was invented by Nikolaus Otto.

What is the engine made of? The simplest ICE consists of a cylinder block in which a crank-connecting rod system, a cylinder-piston group is installed, the block is covered with a cylinder head with a gas distribution mechanism (camshaft and valves), an intake and exhaust system, a fuel and ignition system.