Internal combustion engine device, technical terms (educational program), internal combustion engine operation. Internal combustion engine

29.04.2019

Engine internal combustion, or internal combustion engine is the most common type of engine that can be found on cars. Despite the fact that the internal combustion engine in modern cars consists of many parts, its principle of operation is extremely simple. Let's take a closer look at what an internal combustion engine is and how it functions in a car.

DVS what is it?

The internal combustion engine is a type heat engine, in which part of the chemical energy obtained during the combustion of fuel is converted into mechanical energy, which sets the mechanisms in motion.

Internal combustion engines are divided into categories according to work cycles: two-stroke and four-stroke. They are also distinguished by the method of preparing the fuel-air mixture: with external (injectors and carburetors) and internal (diesel units) mixture formation. Depending on how the energy is converted in the engines, they are divided into piston, jet, turbine and combined.

The main mechanisms of the internal combustion engine

An internal combustion engine is made up of a huge number of elements. But there are basic ones that characterize its performance. Let's look at the structure of the internal combustion engine and its main mechanisms.

1. The cylinder is the most important part of the power unit. Automotive engines, as a rule, have four or more cylinders, up to sixteen on production supercars. The arrangement of cylinders in such engines can be in one of three orders: linear, V-shaped and opposed.

2. The spark plug generates a spark that ignites the air/fuel mixture. Due to this, the combustion process takes place. For the engine to work "like a clock", the spark must be supplied exactly at the right time.

3. The intake and exhaust valves also only function at certain times. One opens when you need to let in the next portion of fuel, the other when you need to release exhaust gases. Both valves are firmly closed when the engine is under compression and combustion strokes. This provides the necessary complete tightness.

4. The piston is a metal part that is shaped like a cylinder. The piston moves up and down inside the cylinder.

5. Piston rings serve as sliding seals for the outer edge of the piston and the inner surface of the cylinder. Their use is due to two purposes:

They don't let you hit combustible mixture into the crankcase of the internal combustion engine from the combustion chamber at the moments of compression and the working cycle.

They prevent oil from getting into the combustion chamber from the crankcase, because there it can ignite. Many cars that burn oil are equipped with older engines and their piston rings no longer seal properly.

6. Connecting rod serves connecting element between piston and crankshaft.

7. The crankshaft converts the translational motion of the pistons into rotational.

8. Carter is located around crankshaft. A certain amount of oil is collected in its lower part (pan).

The principle of operation of the internal combustion engine

In the previous sections, we discussed the purpose and internal combustion engine device. As you already understood, each such engine has pistons and cylinders, inside which thermal energy is converted into mechanical energy. This, in turn, makes the car move. This process repeats itself at an astonishing frequency, several times per second. Due to this, the crankshaft that comes out of the engine rotates continuously.

Let us consider in more detail the principle of operation of an internal combustion engine. The mixture of fuel and air enters the combustion chamber through inlet valve. Then it is compressed and ignited by a spark from a spark plug. When the fuel burns, a very heat, which leads to the appearance of excess pressure in the cylinder. This causes the piston to move towards dead center". He thus makes one working move. When the piston moves down, it rotates the crankshaft through the connecting rod. Then, moving from the bottom dead center to the top, it pushes the waste material in the form of gases through the exhaust valve further into the exhaust system of the machine.

A stroke is a process that occurs in a cylinder in one stroke of the piston. The set of such cycles, which are repeated in strict sequence and for a certain period, is the working cycle of the internal combustion engine.

Inlet

The intake stroke is the first. It starts at the top dead center of the piston. It moves down, sucking a mixture of fuel and air into the cylinder. This stroke occurs when the intake valve is open. By the way, there are engines that have several intake valves. Their specifications significantly affect the power of the engine. In some engines, the time the intake valves are open can be adjusted. This is controlled by pressing the gas pedal. Thanks to such a system, the amount of fuel taken in increases, and after its ignition, the power of the power unit also increases significantly. The car in this case can significantly accelerate.

Compression

The second working cycle of an internal combustion engine is compression. When the piston reaches bottom dead center, it rises. Due to this, the mixture that has entered the cylinder is compressed during the first cycle. The fuel-air mixture is compressed to the size of the combustion chamber. It's the same free place between the tops of the cylinder and the piston, which is in its top dead point. The valves are tightly closed during this stroke. The tighter the formed space, the better the compression obtained. It is very important what condition the piston, its rings and cylinder have. If gaps are present somewhere, then there can be no talk of good compression, and, consequently, the power of the power unit will be significantly lower. The amount of compression determines how worn out the power unit is.

working stroke

This third measure starts at top dead center. And this name he received not by chance. It is during this cycle that the processes that move the car take place in the engine. In this stroke, the ignition system is connected. It is responsible for igniting the air-fuel mixture compressed in the combustion chamber. The principle of operation of the internal combustion engine in this cycle is very simple - the candle of the system gives a spark. After ignition of the fuel, a microexplosion occurs. After that, it sharply increases in volume, forcing the piston to move sharply down. The valves in this stroke are in the closed state, as in the previous one.

Release

The final cycle of the internal combustion engine is exhaust. After the stroke, the piston reaches bottom dead center and then the exhaust valve opens. After that, the piston moves up, and through this valve ejects the exhaust gases from the cylinder. This is the ventilation process. The degree of compression in the combustion chamber, the complete removal of waste materials and the required amount of air-fuel mixture depend on how clearly the valve works.

After this step, everything starts anew. What makes the crankshaft rotate? The fact is that not all the energy is spent on the movement of the car. Part of the energy spins the flywheel, which, under the action of inertial forces, spins the crankshaft of the internal combustion engine, moving the piston to non-working cycles.

Do you know? A diesel engine is heavier than a gasoline engine due to the higher mechanical stress. Therefore, constructors use more massive elements. But the resource of such engines is higher gasoline analogues. Besides, diesel cars ignite much less often than gasoline ones, since diesel is non-volatile.

Advantages and disadvantages

We have learned what an internal combustion engine is, as well as what its structure and principle of operation are. In conclusion, we will analyze its main advantages and disadvantages.

ICE advantages:

1. The possibility of long-term movement on a full tank.

2. Light weight and tank volume.

3. Autonomy.

4. Versatility.

5. Moderate cost.

6. Compact dimensions.

7. Quick start.

8. Ability to use multiple types of fuel.

ICE Disadvantages:

1. Weak operational efficiency.

2. Strong environmental pollution.

3. Mandatory presence of a gearbox.

4. Lack of energy recovery mode.

5. Works underload most of the time.

6. Very noisy.

7. High speed rotation of the crankshaft.

8. Small resource.

Interesting fact! The smallest engine is designed in Cambridge. Its dimensions are 5 * 15 * 3 mm, and its power is 11.2 watts. The crankshaft speed is 50,000 rpm.

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However, lighting gas was suitable not only for lighting.

The credit for creating a commercially successful internal combustion engine belongs to the Belgian mechanic Jean Étienne Lenoir. While working at an electroplating plant, Lenoir came up with the idea that the air-fuel mixture in a gas engine could be ignited by an electric spark, and decided to build an engine based on this idea. Having solved the problems that arose along the way (tight stroke and overheating of the piston, leading to jamming), having thought through the engine cooling and lubrication system, Lenoir created a workable internal combustion engine. In 1864, more than three hundred of these engines were produced. different power. Having grown rich, Lenoir stopped working on further improvement of his car, and this predetermined her fate - she was forced out of the market by a more advanced engine created by the German inventor August Otto and received a patent for the invention of his model. gas engine in 1864.

In 1864, the German inventor Augusto Otto entered into an agreement with the wealthy engineer Langen to implement his invention - the company "Otto and Company" was created. Neither Otto nor Langen possessed sufficient knowledge in the field of electrical engineering and abandoned electric ignition. They ignited with an open flame through a tube. The cylinder of the Otto engine, unlike the Lenoir engine, was vertical. The rotating shaft was placed above the cylinder on the side. Principle of operation: a rotating shaft raised the piston by 1/10 of the height of the cylinder, as a result of which a rarefied space formed under the piston and a mixture of air and gas was sucked in. The mixture then ignited. During the explosion, the pressure under the piston increased to approximately 4 atm. Under the action of this pressure, the piston rose, the volume of gas increased and the pressure fell. The piston, first under gas pressure, and then by inertia, rose until a vacuum was created under it. Thus, the energy of the burnt fuel was used in the engine with maximum completeness. This was Otto's main original find. The downward working stroke of the piston began under the influence of atmospheric pressure, and after the pressure in the cylinder reached atmospheric pressure, the exhaust valve opened, and the piston displaced the exhaust gases with its mass. Due to a more complete expansion of products combustion efficiency this engine was significantly higher than Engine efficiency Lenoir and reached 15%, that is, it exceeded the efficiency of the best steam engines that time. In addition, Otto's engines were almost five times more economical than engines Lenoir, they immediately began to be in great demand. In subsequent years, about five thousand of them were produced. Despite this, Otto worked hard to improve their design. Soon, a crank gear was used. However, the most significant of his inventions was made in 1877, when Otto received a patent for new engine with a four stroke cycle. This cycle still underlies the operation of most gas and gasoline engines to this day.

Types of internal combustion engines

piston engine

rotary internal combustion engine

Gas turbine internal combustion engine

Reciprocating engines - the combustion chamber is contained in a cylinder where the thermal energy of the fuel is converted into mechanical energy, which from forward movement the piston turns into a rotational one with the help of a crank mechanism.

ICEs are classified:

a) By purpose - are divided into transport, stationary and special.

b) By the type of fuel used - light liquid (gasoline, gas), heavy liquid ( diesel fuel, marine fuel oils).

c) According to the method of formation of a combustible mixture - external (carburetor, injector) and internal (in the engine cylinder).

d) According to the method of ignition (with forced ignition, with compression ignition, calorising).

e) According to the location of the cylinders, they are divided into in-line, vertical, opposed with one and two crankshafts, V-shaped with an upper and lower crankshaft, VR-shaped and W-shaped, single-row and double-row star-shaped, H-shaped, double-row with parallel crankshafts, "double fan", diamond-shaped, three-beam and some others.

Petrol

Petrol carburetor

The working cycle of four-stroke internal combustion engines takes two complete revolutions of the crank, consisting of four separate cycles:

intake,
charge compression,
working stroke and
release (exhaust).

The change in working cycles is provided by a special gas distribution mechanism, most often it is represented by one or two camshafts, a system of pushers and valves that directly provide a phase change. Some internal combustion engines have used spool sleeves (Ricardo) for this purpose, having inlet and/or exhaust ports. The communication of the cylinder cavity with the collectors in this case was provided by the radial and rotational movements of the spool sleeve, opening the desired channel with windows. Due to the peculiarities of gas dynamics - the inertia of gases, the time of occurrence of the gas wind, the intake, power stroke and exhaust strokes in a real four-stroke cycle overlap, this is called valve timing overlap. The higher the operating speed of the engine, the greater the phase overlap and the larger it is, the lower the torque of the internal combustion engine by low revs. Therefore, in modern engines internal combustion devices are increasingly being used to change the valve timing during operation. Particularly suitable for this purpose are engines with solenoid valve control (BMW, Mazda). There are also engines with variable degree compression (SAAB), with greater flexibility characteristics.

Two-stroke engines have many layout options and a wide variety of structural systems. The basic principle of any two-stroke engine is the performance by the piston of the functions of a gas distribution element. The working cycle consists, strictly speaking, of three cycles: the working stroke, lasting from the top dead center ( TDC) up to 20-30 degrees to the bottom dead center ( NMT), purge, which actually combines intake and exhaust, and compression, lasting from 20-30 degrees after BDC to TDC. Purging, from the point of view of gas dynamics, is the weak link of the two-stroke cycle. On the one hand, it is impossible to ensure complete separation of the fresh charge and exhaust gases, therefore, either the loss of a fresh mixture is inevitable, literally flying out into the exhaust pipe (if the internal combustion engine is a diesel, we are talking about air loss), on the other hand, the stroke lasts not half a turn, but less, which in itself reduces efficiency. At the same time, the duration is extremely important process gas exchange, four-stroke engine occupying half the working cycle cannot be increased. Two-stroke engines may not have a gas distribution system at all. However, if we are not talking about simplified cheap engines, a two-stroke engine is more complicated and expensive due to the obligatory use of a blower or a pressurization system, the increased heat stress of the CPG requires more expensive materials for pistons, rings, cylinder liners. The performance by the piston of the functions of the gas distribution element obliges to have its height not less than the piston stroke + the height of the purge windows, which is uncritical in a moped, but significantly makes the piston heavier even at relatively low powers. When the power is measured in hundreds of horsepower, the increase in piston mass becomes a very serious factor. The introduction of vertically stroked distributor sleeves in Ricardo engines was an attempt to make it possible to reduce the size and weight of the piston. The system turned out to be complicated and expensive in execution, except for aviation, such engines were not used anywhere else. Exhaust valves (with direct-flow valve scavenging) have twice the heat density compared to four-stroke exhaust valves and worse conditions for heat removal, and their seats have a longer direct contact with the exhaust gases.

The simplest in terms of the order of operation and the most complex in terms of design is the Fairbanks-Morse system, presented in the USSR and Russia, mainly by diesel locomotives of the D100 series. Such an engine is a symmetrical two-shaft system with diverging pistons, each of which is connected to its own crankshaft. Thus, this engine has two crankshafts mechanically synchronized; the one connected to the exhaust pistons is ahead of the intake by 20-30 degrees. Due to this advance, the quality of the scavenging is improved, which in this case is direct-flow, and the filling of the cylinder is improved, since the exhaust windows are already closed at the end of the scavenging. In the 30s - 40s of the twentieth century, schemes with pairs of diverging pistons were proposed - diamond-shaped, triangular; There were aviation diesel engines with three radially diverging pistons, of which two were inlet and one exhaust. In the 1920s, Junkers proposed a single-shaft system with long connecting rods connected to the fingers of the upper pistons with special rocker arms; the upper piston transmitted forces to the crankshaft by a pair of long connecting rods, and there were three crankshafts per cylinder. There were also square pistons of the scavenging cavities on the rocker arms. Two-stroke engines with divergent pistons of any system have, basically, two drawbacks: firstly, they are very complex and large, and secondly, exhaust pistons and sleeves in the area of exhaust windows have significant thermal tension and a tendency to overheat. Exhaust piston rings are also thermally stressed, prone to coking and loss of elasticity. These features make the design of such engines a non-trivial task.

Direct-flow valve-scavenged engines are equipped with a camshaft and exhaust valves. This significantly reduces the requirements for materials and execution of the CPG. The intake is carried out through the windows in the cylinder liner, opened by the piston. This is how most modern two-stroke diesels are assembled. The window area and the sleeve in the lower part are in many cases cooled by charge air.

In cases where one of the main requirements for the engine is its reduction in cost, different types of crank-chamber contour window-window purge are used - loop, reciprocating-loop (deflector) in various modifications. To improve the parameters of the engine, a variety of design techniques are used - a variable length of the intake and exhaust channels, the number and location of bypass channels can vary, spools, rotating gas cutters, sleeves and curtains are used that change the height of the windows (and, accordingly, the moments of the start of intake and exhaust). Most of these engines are air-cooled passively. Their disadvantages are the relatively low quality of gas exchange and the loss of the combustible mixture during purging; in the presence of several cylinders, the sections of the crank chambers have to be separated and sealed, the design of the crankshaft becomes more complicated and more expensive.

Additional units required for internal combustion engines

The disadvantage of an internal combustion engine is that it develops its highest power only in a narrow rev range. Therefore, an essential attribute of an internal combustion engine is a transmission. Only in some cases (for example, in airplanes) can a complex transmission be dispensed with. The idea of a hybrid car is gradually conquering the world, in which the engine always works in the optimal mode.

In addition, an internal combustion engine needs a power system (for supplying fuel and air - cooking fuel-air mixture), exhaust system (to remove exhaust gases), you can’t do without a lubrication system (designed to reduce friction forces in engine mechanisms, protect engine parts from corrosion, and also together with the cooling system to maintain optimal thermal conditions), cooling systems (for maintaining the optimal thermal regime of the engine), starting system (starting methods are used: electric starter, with the help of an auxiliary starting motor, pneumatic, with the help of human muscle power), the ignition system (for igniting the fuel-air mixture, used in engines with positive ignition).

Notes

General ICE device

Each of the motors has a cylinder and a piston. In the first, thermal energy is converted into mechanical energy, which can cause the car to move. In just one minute, this process is repeated several hundred times, due to which the crankshaft that exits the engine rotates continuously.

The engine of the machine consists of several complexes of systems and mechanisms that convert energy into mechanical work.

Its base is:

gas distribution;

crank mechanism.

In addition, the following systems work in it:

ignition;
cooling;

crank mechanism

Thanks to him, the reciprocating motion of the crankshaft turns into rotational. The latter is transmitted to all systems more easily than the cyclic, especially since the wheels are the final link in the transmission. And they work by rotation.

If the car was not wheeled vehicle, then this mechanism for locomotion might not have been necessary. However, in the case of a machine, the crank operation is fully justified.

Gas distribution mechanism

Thanks to the timing, the working mixture or air enters the cylinders (depending on the characteristics of the formation of the mixture in the engine), then the exhaust gases and combustion products are removed.

At the same time, the exchange of gases occurs at the appointed time in a certain amount, organized with cycles and guaranteeing a high-quality working mixture, as well as obtaining the greatest effect from the generated heat.

Supply system

The mixture of air and fuel burns in the cylinders. The system under consideration regulates their supply in a strict amount and proportion. There is external and internal mixing. In the first case, air and fuel are mixed outside the cylinder, and in the other - inside it.

The feed system with external mixture formation has special device called a carburetor. In it, the fuel is sprayed into the air, and then enters the cylinders.

A car with an internal mixture formation system is called injection and diesel. They fill the cylinders with air, where fuel is injected through special mechanisms.

Ignition system

Here, forced ignition of the working mixture in the motor occurs. Diesel units this is not necessary, since their process is carried out through high air, which becomes actually red-hot.

Most engines use spark electrical discharge. However, in addition, ignition tubes can be used that ignite the working mixture with a burning substance.

It can be set on fire in other ways. But the electrospark system continues to be the most practical today.

Start

This system achieves the rotation of the crankshaft of the motor at startup. This is necessary to start the functioning of individual mechanisms and the engine itself as a whole.

To start, the starter is mainly used. Thanks to him, the process is carried out easily, reliably and quickly. But a variant of a pneumatic unit is also possible, which works on a reserve in receivers or is provided with an electrically driven compressor.

The simplest system is the crank, through which the crankshaft rotates in the engine and the operation of all mechanisms and systems begins. Until recently, all drivers carried it with them. However, there was no question of any convenience in this case. So today everyone does without it.

Cooling

The task of this system is to maintain a certain temperature of the operating unit. The fact is that combustion in the cylinders of the mixture occurs with the release of heat. The components and parts of the motor heat up, and they need to be constantly cooled in order to work normally.

The most common are liquid and air systems.

In order for the engine to cool constantly, a heat exchanger is needed. In motors with a liquid version, its role is played by a radiator, which consists of many tubes for moving it and transferring heat to the walls. The outlet is further increased through the fan, which is installed next to the heatsink.

In air-cooled devices, the surfaces of the hottest elements are finned, which significantly increases the heat exchange area.

This cooling system is inefficient, and therefore it is rarely installed on modern cars. It is mainly used on motorcycles and small internal combustion engines that do not require hard work.

Lubrication system

Lubrication of parts is necessary to reduce the loss of mechanical energy that occurs in the crank mechanism and timing. In addition, the process helps to reduce wear on parts and some cooling.

Lubrication in car engines is mainly used under pressure, when oil is supplied through pipelines by means of a pump.

Some elements are lubricated by splashing or dipping in oil.

Two-stroke and four-stroke motors

The device of the car engine of the first type is currently used in a rather narrow range: on mopeds, cheap motorcycles, boats and petrol mowers. Its disadvantage is the loss of the working mixture during the removal of exhaust gases. In addition, forced purge and excessive requirements for the thermal stability of the exhaust valve cause an increase in the price of the motor.

In a four-stroke engine, these disadvantages are not present due to the presence of a gas distribution mechanism. However, this system also has its problems. Best Mode engine operation will be achieved in a very narrow range of revolutions of the crankshaft.

The development of technology and the emergence of electronic control units made it possible to solve this problem. In internal organization engine is now included electromagnetic control, which selects optimal mode gas distribution.

Principle of operation

ICE works as follows. After the working mixture enters the combustion chamber, it is compressed and ignited by a spark. During combustion, super-strong pressure is formed in the cylinder, which sets the piston in motion. It begins to move towards bottom dead center, which is the third stroke (after intake and compression), called the power stroke. At this time, thanks to the piston, the crankshaft begins to rotate. The piston, in turn, moving to the top dead center, pushes out the exhaust gases, which is the fourth stroke of the engine - exhaust.

All four stroke operation happens quite simply. To make it easier to understand how general device the engine of the car, and its operation, it is convenient to watch a video that clearly demonstrates the functioning of the internal combustion engine engine.

tuning

Many car owners, getting used to their car, want to get from it more possibilities than she can give. Therefore, engine tuning is often done for this, increasing its power. This can be done in several ways.

For example, chip tuning is known, when, by computer reprogramming, the motor is tuned for more dynamic operation. This method has both supporters and opponents.

A more traditional method is engine tuning, in which some of its alterations are carried out. For this, a replacement is made with pistons and connecting rods suitable for it; a turbine is installed; complex manipulations with aerodynamics are carried out and so on.

The device of a car engine is not so complicated. However, due to the huge number of elements included in it, and the need to coordinate them among themselves, in order for any alterations to have the desired result, high professionalism of the person who will carry them out is required. Therefore, before deciding on this, it is worth spending the effort to find a real master of his craft.

For about a hundred years, everywhere in the world the main power unit on cars and motorcycles, tractors and combines, other equipment is an internal combustion engine. Coming at the beginning of the twentieth century to replace external combustion engines (steam), it remains the most cost-effective type of motor in the twenty-first century. In this article, we will consider in detail the device, the principle of operation various kinds ICE and its main auxiliary systems.

Definition and general features of the internal combustion engine

The main feature of any internal combustion engine is that the fuel ignites directly inside its working chamber, and not in additional external carriers. During operation, chemical and thermal energy from fuel combustion is converted into mechanical work. The principle of operation of the internal combustion engine is based on the physical effect of thermal expansion of gases, which is formed during the combustion of the fuel-air mixture under pressure inside the engine cylinders.

Classification of internal combustion engines

In the process of evolution of internal combustion engines, the following types of these motors have proven their effectiveness:

Piston internal combustion engines. In them, the working chamber is located inside the cylinders, and the thermal energy is converted into mechanical work by means of a crank mechanism that transfers the energy of motion to the crankshaft. piston motors divided in turn into
carburetor, in which air-fuel mixture formed in the carburetor, injected into the cylinder and ignited there by a spark from a spark plug;

injection, in which the mixture is fed directly into intake manifold, through special nozzles, under the control of the electronic control unit, and also ignites by means of a candle;
diesel, in which the ignition of the air-fuel mixture occurs without a candle, by compressing air, which is heated by pressure from a temperature exceeding the combustion temperature, and fuel is injected into the cylinders through nozzles.
Rotary piston internal combustion engines. in motors of this type thermal energy is converted into mechanical work by rotating the working gases of the rotor special form and profile. The rotor moves along a "planetary trajectory" inside the working chamber, which has the shape of a "eight", and performs the functions of both a piston and a timing (gas distribution mechanism), and a crankshaft.
gas turbine internal combustion engines. In these motors, the transformation of thermal energy into mechanical work is carried out by rotating the rotor with special wedge-shaped blades, which drives the turbine shaft.

The most reliable, unpretentious, economical in terms of fuel consumption and the need for regular maintenance are piston engines.

Equipment with other types of internal combustion engines can be included in the Red Book. Nowadays only Mazda makes cars with rotary piston engines. An experimental series of cars with a gas turbine engine was produced by Chrysler, but it was in the 60s, and none of the automakers returned to this issue. IN THE USSR gas turbine engines tanks "T-80" and landing ships "Zubr" were equipped, but in the future it was decided to abandon this type of motor. In this regard, let us dwell in detail on the “winning world domination» piston internal combustion engines.

The engine housing combines into a single organism:

cylinder block, inside the combustion chambers of which the fuel-air mixture ignites, and the gases from this combustion drive the pistons;
crank mechanism, which transfers the energy of movement to the crankshaft;
gas distribution mechanism, which is designed to ensure the timely opening / closing of valves for the inlet / outlet of the combustible mixture and exhaust gases;
supply system ("injection") and ignition ("ignition") of the fuel-air mixture;
combustion products removal system(exhaust gases).

Cross section of a four-stroke internal combustion engine

When the engine is started, an air-fuel mixture is injected into its cylinders through the intake valves and ignites there from a spark plug spark. During combustion and thermal expansion of gases from excess pressure, the piston sets in motion, transferring mechanical work to the rotation of the crankshaft.

Job piston engine internal combustion is carried out cyclically. These cycles are repeated at a frequency of several hundred times per minute. This ensures continuous translational rotation of the crankshaft exiting the engine.

Let's define terminology. A stroke is a work process that occurs in an engine in one stroke of the piston, more precisely, in one of its movements in one direction, up or down. A cycle is a set of cycles that repeat in a certain sequence. By the number of cycles within one worker ICE cycle They are subdivided into two-stroke (the cycle is carried out in one revolution of the crankshaft and two strokes of the piston) and four-stroke (for two revolutions of the crankshaft and four pistons). At the same time, both in those and in other engines, the working process goes according to the following plan: intake; compression; combustion; expansion and release.

The principles of operation of the internal combustion engine

- The principle of operation of a two-stroke engine

When the engine starts, the piston, entrained by the rotation of the crankshaft, begins to move. As soon as it reaches its bottom dead center (BDC) and proceeds to move up, a fuel-air mixture is supplied to the combustion chamber of the cylinder.

In its upward movement, the piston compresses it. When the piston reaches its top dead center (TDC), a spark from the electronic spark plug ignites the air-fuel mixture. Instantly expanding, the vapors of burning fuel rapidly push the piston back to the bottom dead center.

At this time, the exhaust valve opens, through which hot exhaust gases are removed from the combustion chamber. Having passed BDC again, the piston resumes its movement to TDC. During this time, the crankshaft makes one revolution.

With a new movement of the piston, the inlet channel of the fuel-air mixture opens again, which replaces the entire volume of exhaust gases, and the whole process is repeated anew. Due to the fact that the work of the piston in such motors is limited to two strokes, it makes a much smaller number of movements per unit of time than in a four-stroke engine. Friction losses are minimized. However, a lot of heat energy is released, and two-stroke engines heat up faster and more strongly.

In two-stroke engines, the piston replaces valve train gas distribution, in the course of its movement at certain moments, opening and closing the working openings of the inlet and outlet in the cylinder. Worse, compared to a four-stroke engine, gas exchange is the main disadvantage push-pull system ICE. At the moment of removal of exhaust gases, a certain percentage of not only the working substance, but also power is lost.

Areas of practical application two-stroke engines internal combustion steel mopeds and scooters; boat motors, lawn mowers, chainsaws, etc. low power technology.

These shortcomings are deprived of four-stroke internal combustion engines, which, in various options, and are installed on almost all modern cars, tractors and other equipment. In them, the intake / exhaust of a combustible mixture / exhaust gases are carried out as separate workflows, and not combined with compression and expansion, as in two-stroke ones. With the help of the gas distribution mechanism, the mechanical synchronization of the operation of the intake and exhaust valves with the crankshaft speed is ensured. In a four-stroke engine, the injection of the fuel-air mixture occurs only after the complete removal of exhaust gases and the closing of the exhaust valves.

The working process of an internal combustion engine

Each stroke of work is one stroke of the piston in the range from top to bottom dead center. In this case, the engine goes through the following phases of operation:

Stroke one, inlet. The piston moves from top dead center to bottom dead center. At this time, a vacuum occurs inside the cylinder, the intake valve opens and the fuel-air mixture enters. At the end of the intake, the pressure in the cylinder cavity is in the range from 0.07 to 0.095 MPa; temperature - from 80 to 120 degrees Celsius.
Bar two, compression. When the piston moves from bottom to top dead center and the intake and exhaust valves are closed, the combustible mixture is compressed in the cylinder cavity. This process is accompanied by an increase in pressure up to 1.2-1.7 MPa, and temperature - up to 300-400 degrees Celsius.
Bar three, expansion. The fuel-air mixture ignites. This is accompanied by the release of a significant amount of thermal energy. The temperature in the cavity of the cylinder rises sharply to 2.5 thousand degrees Celsius. Under pressure, the piston moves quickly to its bottom dead center. The pressure indicator in this case is from 4 to 6 MPa.
Bar four, issue. During the reverse movement of the piston to the top dead center, the exhaust valve opens, through which the exhaust gases are pushed out of the cylinder into the exhaust pipe, and then into environment. The pressure indicators in the final stage of the cycle are 0.1-0.12 MPa; temperature - 600-900 degrees Celsius.

Auxiliary systems of the internal combustion engine

The ignition system is part of the electrical equipment of the machine and is designed to provide a spark, igniting the fuel-air mixture in the working chamber of the cylinder. The components of the ignition system are:

Power supply. During engine start, this is accumulator battery, and during its operation - the generator.
Switch, or ignition switch. It was previously mechanical, and in last years increasingly electric contact device to supply electricity.
Energy storage. A coil, or autotransformer, is a unit designed to store and convert enough energy to cause the desired discharge between the spark plug electrodes.
Ignition distributor (distributor). A device designed to distribute an impulse high voltage along the wires leading to the candles of each of the cylinders.

ICE ignition system

- intake system

The ICE intake system is designed For uninterrupted filing into the motor atmospheric air, for mixing it with fuel and preparing a combustible mixture. It should be noted that in carbureted engines The past intake system consists of an air duct and an air filter. And that's it. Part intake system modern cars, tractors and other equipment includes:

air intake. It is a branch pipe of a form convenient for each specific engine. Through him atmospheric air is sucked into the engine, through the difference in pressure in the atmosphere and in the engine, where a vacuum occurs when the pistons move.
Air filter. This consumable, designed to clean the air entering the motor from dust and solid particles, their delay on the filter.
throttle valve. Air valve designed to regulate the supply of the desired amount of air. Mechanically, it is activated by pressing the gas pedal, and in modern technology- with the help of electronics.
Intake manifold. Distributes the air flow through the engine cylinders. To give air flow the desired distribution, special intake flaps and a vacuum booster are used.

Fuel system, or system ICE power supply, "responsible" for uninterrupted fuel supply to form a fuel-air mixture. Part fuel system includes:

Fuel tank- a container for storing gasoline or diesel fuel, with a device for taking fuel (pump).
Fuel lines- a set of tubes and hoses through which its "food" enters the engine.
Mixing device, i.e. carburetor or injector- a special mechanism for the preparation of the fuel-air mixture and its injection into the internal combustion engine.
Electronic control unit(ECU) mixture formation and injection - in injection engines this device is "responsible" for synchronous and efficient work on the formation and supply of a combustible mixture to the engine.
Fuel pump- an electrical device for pumping gasoline or diesel fuel into the fuel line.
The fuel filter is a consumable for additional purification of fuel during its transportation from the tank to the engine.

ICE fuel system diagram

- Lubrication system

Purpose of the system engine lubricants -friction reduction and its destructive effect on parts; abduction parts of the excess heat; removal products soot and wear; protection metal against corrosion. The engine lubrication system includes:

Oil pan- storage tank engine oil. The oil level in the sump is controlled not only by a special dipstick, but also by a sensor.
Oil pump- pumps oil from the sump and delivers it to the necessary engine parts through special drilled channels - "lines". Under the influence of gravity, the oil flows down from the lubricated parts, back into the oil pan, accumulates there, and the lubrication cycle is repeated again.
Oil filter traps and removes solid particles from engine oil formed from soot and wear products of parts. The filter element is always replaced with a new one with every engine oil change.
Oil radiator Designed to cool engine oil using liquid from the engine cooling system.

exhaust internal combustion engine system serves for removing spent gases And noise reduction motor work. In modern technology exhaust system consists of the following parts (in order of exhaust gas exit from the engine):

An exhaust manifold. This is a pipe system made of heat-resistant cast iron, which receives hot exhaust gases, dampens their primary oscillatory process and sends them further to the exhaust pipe.
Downpipe- a curved gas outlet made of fire-resistant metal, popularly referred to as "pants".
Resonator, or, in popular language, the “bank” of the muffler is a container in which exhaust gases are separated and their speed is reduced.
Catalyst- a device designed for purification of exhaust gases and their neutralization.
Muffler- a container with a complex of special partitions designed to repeatedly change the direction of gas flow and, accordingly, their noise level.

Exhaust system

- Cooling system

If mopeds, scooters and inexpensive motorcycles still use air system engine cooling - oncoming air flow, then for more powerful technology it is, of course, not enough. Works here fluid system cooling designed For absorbing excess heat at the motor and reduction of thermal loads on its details.

Radiator The cooling system is used to release excess heat to the environment. It consists of a large number of curved aluminum tubes, with fins for additional heat dissipation.
Fan designed to enhance the cooling effect on the radiator from the oncoming air flow.
Water pump(pump) - "drives" the coolant in the "small" and "large" circles, ensuring its circulation through the engine and radiator.
Thermostat- a special valve that ensures the optimum temperature of the coolant by starting it in a "small circle", bypassing the radiator (when the engine is cold) and in a "large circle", through the radiator - when the engine is warm.

The coordinated work of these auxiliary systems ensures maximum efficiency from the internal combustion engine and its reliability.

In conclusion, it should be noted that in the foreseeable future, worthy competitors to the internal combustion engine are not expected to appear. There is every reason to assert that in its modern, improved form, it will remain the dominant type of motor in all sectors of the world economy for several decades to come.

Before considering the issue how a car engine works, it is necessary at least in general terms understand his device. In any car, an internal combustion engine is installed, the operation of which is based on the conversion of thermal energy into mechanical energy. Let's look deeper into this mechanism.

How a car engine works - we study the device diagram

The classic engine device includes a cylinder and a crankcase, closed in the lower part by a pan. Inside the cylinder is located with various rings, which moves in a certain sequence. It has the shape of a glass, in its upper part there is a bottom. To finally understand how a car engine works, you need to know that the piston with the help of piston pin and the connecting rod is connected to the crankshaft.

For smooth and soft rotation, indigenous and connecting rod bearings playing the role of bearings. The composition of the crankshaft includes the cheeks, as well as the main and connecting rod journals. All these parts, assembled together, are called a crank mechanism, which converts the reciprocating movement of the piston into circular rotation.

The upper part of the cylinder is closed by the head, where the intake and exhaust valves. They open and close in accordance with the movement of the piston and the movement of the crankshaft. To accurately understand how a car engine works, the videos in our library should be studied in as much detail as the article. In the meantime, we will try to express its effect in words.

How a car engine works - briefly about complex processes

So, the piston displacement limit has two extreme positions- top and bottom dead spots. In the first case, the piston is at the maximum distance from the crankshaft, and the second option is the smallest distance between the piston and the crankshaft. In order to ensure that the piston passes through dead centers without stopping, a flywheel made in the form of a disk is used.

An important parameter for internal combustion engines is the compression ratio, which directly affects its power and efficiency.

To correctly understand the principle of operation of a car engine, you need to know that it is based on the use of the work of gases expanded during the heating process, as a result of which the piston moves between the upper and lower dead spots. At top position The piston burns fuel that enters the cylinder and mixes with air. As a result, the temperature of gases and their pressure increases significantly.

Gases do useful work, due to which the piston moves down. Further, through the crank mechanism, the action is transmitted to the transmission, and then to car wheel. Waste products are removed from the cylinder through the exhaust system, and a new portion of fuel is supplied in their place. The entire process, from fuel injection to exhaust gas, is called the engine's duty cycle.

The principle of operation of a car engine - differences in models

There are several main types of internal combustion engines. The simplest is an in-line engine. Arranged in one row, they make up a certain working volume as a whole. But gradually, some manufacturers moved away from this manufacturing technology to a more compact version.

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