The principle of operation of piston engines. Internal combustion engine The main disadvantage of reciprocating internal combustion engines

Engine Features internal combustion

Internal combustion engines belong to the most common type of heat engines, i.e., engines in which the heat released during the combustion of fuel is converted into mechanical energy. Heat engines can be divided into two main groups:

external combustion engines - steam engines, steam turbines, Stirling engines, etc. Of the engines of this group, only Stirling engines are considered in the textbook, since their designs are close to the designs of internal combustion engines;

internal combustion engines. In internal combustion engines, the processes of burning fuel, releasing heat and converting part of it into mechanical work take place directly inside the engine. These engines include reciprocating and combined engines, gas turbines and jet engines.

Schematic diagrams internal combustion engines are shown in fig. one.

For a piston engine (Fig. 1, a), the main parts are: cylinder cover (head) of the cylinder; crankcase piston; connecting rod; crankshaft intake and exhaust valves. Fuel and the air necessary for its combustion are introduced into the volume of the engine cylinder, limited by the bottom of the cover, the walls of the cylinder and the bottom of the piston. The gases of high temperature and pressure formed during combustion press on the piston and move it in the cylinder. The translational movement of the piston through the connecting rod is converted into rotational crankshaft located in the crankcase. In connection with the reciprocating motion of the piston, the combustion of fuel in piston engines is possible only in periodically successive portions, and the combustion of each portion must be preceded by a number of preparatory processes.

V gas turbines(Fig. 1, b) fuel combustion occurs in a special combustion chamber. Fuel is supplied to it by a pump through a nozzle. The air required for combustion is forced into the combustion chamber by a compressor mounted on the same shaft as the gas turbine impeller. The combustion products enter the gas turbine through a guide vane.

A gas turbine having working bodies in the form of blades of a special profile, located on the disk and forming, together with the latter, a rotating impeller, can operate at a high speed. The use of several consecutive rows of blades in a turbine (multi-stage turbines) makes it possible to use the energy of hot gases more fully. However, gas turbines are still inferior in terms of efficiency to reciprocating internal combustion engines, especially when operating at partial load, and, in addition, they are characterized by a high heat stress of the impeller blades due to their continuous operation in a high-temperature gas environment. With a decrease in the temperature of the gases entering the turbine, to increase the reliability of the blades, the power decreases and the efficiency of the turbine deteriorates. Gas turbines are widely used as auxiliary units in piston and jet engines, as well as independent power plants. The use of heat-resistant materials and cooling of the blades, the improvement of the thermodynamic schemes of gas turbines can improve their performance and expand the scope.

Rice. 1. Schemes of internal combustion engines

In liquid-propellant jet engines (Fig. 1, c), liquid fuel and oxidizer are supplied in one way or another (for example, by pumps) under pressure from tanks to the combustion chamber. The combustion products expand in the nozzle and flow out into the environment at high speed. The outflow of gases from the nozzle is the cause of the jet thrust of the engine.

A positive property of jet engines should be considered that their jet thrust is almost independent of the speed of the installation, and its power increases with an increase in the speed of air entering the engine, that is, with an increase in the speed of movement. This property is used when applying turbojet engines in aviation. The main disadvantages of jet engines are relatively low efficiency and a relatively short service life.

Combined internal combustion engines are called engines consisting of a piston part and several compression and expansion machines (or devices), as well as devices for supplying and removing heat, united by a common working fluid. A piston internal combustion engine is used as the piston part of the combined engine.

Energy in such an installation is transmitted to the consumer by the shaft of the piston part, or by the shaft of another expansion machine, or by both shafts simultaneously. The number of compression and expansion machines, their types and designs, their connection with the piston part and among themselves are determined by the purpose of the combined engine, its layout and operating conditions. The most compact and economical combined engines, in which the continuation of the expansion of the exhaust gases of the piston part is carried out in a gas turbine, and the fresh charge is pre-compressed in a centrifugal or axial compressor (the latter has not yet gained distribution), and the power is usually transmitted to the consumer through the crankshaft of the piston part.

A piston engine and a gas turbine as part of a combined engine successfully complement each other: in the first, the heat of small volumes of gas at high pressure is most efficiently converted into mechanical work, and in the second, the heat of large volumes of gas at low pressure is best used.

A combined engine, one of the widespread schemes of which is shown in fig. 2 consists of a piston part, which is used as a piston internal combustion engine, a gas turbine and a compressor. The exhaust gases after the reciprocating engine, while still at high temperature and pressure, rotate the blades of the impeller of the gas turbine, which transmits torque to the compressor. The compressor sucks in air from the atmosphere and, under a certain pressure, pumps it into the cylinders of a piston engine. Increasing the filling of the engine cylinders with air by increasing the intake pressure is called boost. When boosted, the density of the air increases and therefore the fresh charge filling the cylinder at intake increases compared to the charge of air in the same engine without boost.

For the combustion of the fuel introduced into the cylinder, a certain mass of air is required (for complete combustion of 1 kg of liquid fuel, theoretically, about 15 kg of air is needed). Therefore, the more air enters the cylinder, the more fuel can be burned in it, i.e., get more power.

The main advantages of a combined engine are small volume and weight per 1 kW, as well as high efficiency, often exceeding that of a conventional piston engine.

The most economical are piston and combined internal combustion engines, which are widely used in transport and stationary energy. They have a fairly long service life, relatively small dimensions and mass, high efficiency, their characteristics are in good agreement with the characteristics of the consumer. The main disadvantage of engines should be considered the reciprocating movement of the piston, associated with the presence of a crank mechanism, which complicates the design and limits the possibility of increasing the speed, especially with significant engine sizes.

Rice. 2. Scheme of the combined engine

The textbook deals with reciprocating and combined internal combustion engines, which are widely used.

TO category: - Design and operation of the engine

CYCLES OF INTERNAL COMBUSTION ENGINES

The idea of using organic fuel combustion products as a working fluid belongs to Sadi Carnot. He substantiated the principle of operation of an internal combustion engine (ICE) with pre-compression of air in 1824, but due to limited technical capabilities, the creation of such a machine could not be realized.

In 1895, in Germany, engineer R. Diesel built an engine with internal mixing of air and liquid fuel. In such an engine, only air is compressed, and then fuel is injected into it through the nozzle. Due to the separate compression of air in the cylinder of such an engine, it turned out great pressure and temperature, and the fuel injected there spontaneously ignited. Such engines are called diesel engines in honor of their inventor.

The main advantages of reciprocating internal combustion engines compared to PTU are their compactness and high temperature level of heat supply to the working fluid. The compactness of the internal combustion engine is due to the combination of three elements of a heat engine in the engine cylinder: a hot heat source, compression and expansion cylinders. Since the ICE cycle is open, it uses the external environment (exhaust of combustion products) as a cold source of heat. The small dimensions of the internal combustion engine cylinder practically remove the restrictions on the maximum temperature of the working fluid. The internal combustion engine cylinder has forced cooling, and the combustion process is fast, so the metal of the cylinder has an acceptable temperature. The efficiency of such engines is high.

The main disadvantage of piston internal combustion engines is the technical limitation of their power, which is directly dependent on the volume of the cylinder.

The principle of operation of piston internal combustion engines

Consider the principle of operation of piston internal combustion engines using the example of a four-stroke carburetor engine(Otto engine). A diagram of a cylinder with a piston of such an engine and a diagram of the change in gas pressure in its cylinder depending on the position of the piston (indicator diagram) are shown in fig. 11.1.

The first stroke of the engine is characterized by the opening of the intake valve 1k and by moving the piston from top dead center (TDC) to bottom dead center (BDC) drawing air or air-fuel mixture into the cylinder. On the indicator diagram, this is the line 0-1, going from the ambient pressure Р os to the rarefaction area created by the piston when it moves to the right.

The second stroke of the engine begins with the valves closed by moving the piston from BDC to TDC. In this case, the working fluid is compressed with an increase in its pressure and temperature (line 1-2). Before the piston reaches TDC, the fuel ignites, resulting in a further increase in pressure and temperature. The process of fuel combustion itself (line 2-3) is completed already when the piston passes TDC. The second stroke of the engine is considered completed when the piston reaches TDC.

The third stroke is characterized by the movement of the piston from TDC to BDC, (working stroke). Only in this cycle is useful mechanical work obtained. Complete combustion of the fuel is completed in (3) and expansion of the combustion products occurs at (3-4).

The fourth stroke of the engine begins when the piston reaches BDC and the exhaust valve 2k opens. At the same time, the gas pressure in the cylinder drops sharply and when the piston moves towards TDC, the gases are pushed out of the cylinder. When gases are pushed out in the cylinder, the pressure is greater than atmospheric pressure, because gases must overcome the resistance of the exhaust valve, exhaust pipe, muffler, etc. in the exhaust tract of the engine. Having reached the TDC position with the piston, valve 2k closes and the internal combustion engine cycle begins anew with the opening of valve 1k, etc.

Area limited indicator diagram 0-1-2-3-4-0, corresponds to two turns crankshaft engine (full 4 cycles of the engine). To calculate the power of the internal combustion engine, the average indicator pressure of the engine Р i is used. This pressure corresponds to the area 0-1-2-3-4-0 (Fig. 11.1) divided by the piston stroke in the cylinder (the distance between TDC and BDC). Using the indicator pressure, the work of the internal combustion engine for two revolutions of the crankshaft can be represented as the product of P i per piston stroke L (the area of the shaded rectangle in Fig. 11.1) and the cross-sectional area of \u200b\u200bthe cylinder f. The indicator power of the internal combustion engine per cylinder in kilowatts is determined by the expression

, (11.1)

where P i - average indicator pressure, kPa; f - cylinder cross-sectional area, m 2; L - piston stroke, m; n - number of revolutions of the crankshaft, s -1; V \u003d fL - useful volume of the cylinder (between TDC and BDC ), m 3 .

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 with 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 had sufficient knowledge 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 action 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 the more complete expansion of the combustion products, the efficiency of this engine was significantly higher than the efficiency of the Lenoir engine and reached 15%, that is, it exceeded the efficiency of the best steam engines that time. In addition, Otto engines were almost five times more economical than Lenoir engines, they immediately became 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.

Types of internal combustion engines

piston engine

rotary internal combustion engine

Gas turbine internal combustion engine

Piston engines - the combustion chamber is contained in a cylinder, where the thermal energy of the fuel is converted into mechanical energy, which is converted from the translational movement of the piston into rotational motion using 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) By way of education 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 full turnover 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, modern internal combustion engines are increasingly using devices that allow you to change the valve timing during operation. Particularly suitable for this purpose are engines with solenoid valve control (BMW, Mazda). Variable compression ratio (SAAB) engines are also available for greater flexibility.

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 exhaust pipe(if the internal combustion engine is diesel, we are talking about air loss), on the other hand, the power stroke does not last half a turn, but less, which in itself reduces efficiency. At the same time, the duration of the extremely important process of gas exchange, which in a four-stroke engine takes 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 not critical 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 heat dissipation conditions, and their seats have 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 diesel engines 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 basically have two disadvantages: firstly, they are very complex and bulky, and secondly, the exhaust pistons and liners in the area of the 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 to reduce its cost, are used different types crank-chamber contour window-window purge - 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 divided 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), an exhaust system (for 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 a 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 engine, pneumatic, with the help of human muscle power), ignition system (for igniting the fuel-air mixture, used for engines with forced ignition).

Notes

Links

Ben Knight "Increasing mileage" //Article on technologies that reduce fuel consumption of automotive internal combustion engines

At present, the internal combustion engine is the main type car engine. An internal combustion engine (abbreviated name - ICE) is a heat engine that converts the chemical energy of fuel into mechanical work.

There are the following main types of internal combustion engines: piston, rotary piston and gas turbine. Of the presented types of engines, the most common is a piston internal combustion engine, so the device and the principle of operation are considered using its example.

Virtues piston internal combustion engine, which ensured its widespread use, are: autonomy, versatility (combination with various consumers), low cost, compactness, low weight, the ability to quickly start, multi-fuel.

However, internal combustion engines have a number of significant shortcomings, which include: high noise level, high crankshaft speed, exhaust gas toxicity, low resource, low coefficient useful action.

Depending on the type of fuel used, gasoline and diesel engines are distinguished. Alternative fuels used in internal combustion engines are natural gas, alcohol fuels - methanol and ethanol, hydrogen.

From the point of view of ecology, the hydrogen engine is promising, because. does not create harmful emissions. Along with internal combustion engines, hydrogen is used to create electrical energy in fuel cells cars.

Internal combustion engine device

A piston internal combustion engine includes a housing, two mechanisms (crank and gas distribution) and a number of systems (inlet, fuel, ignition, lubrication, cooling, exhaust and control system).

The engine housing integrates the cylinder block and the cylinder head. The crank mechanism converts the reciprocating motion of the piston into rotational motion of the crankshaft. The gas distribution mechanism ensures the timely supply of air or a fuel-air mixture to the cylinders and the release of exhaust gases.

The engine management system provides electronic control operation of internal combustion engine systems.

The operation of the internal combustion engine

Principle ICE operation is based on the effect of thermal expansion of gases that occurs during the combustion of the fuel-air mixture and ensures the movement of the piston in the cylinder.

The operation of a piston internal combustion engine is carried out cyclically. Each work cycle occurs in two revolutions of the crankshaft and includes four cycles (four-stroke engine): intake, compression, power stroke and exhaust.

During the intake and power strokes, the piston moves down, while the compression and exhaust strokes move up. The operating cycles in each of the engine cylinders do not coincide in phase, which ensures uniform operation of the internal combustion engine. In some designs of internal combustion engines, the operating cycle is implemented in two cycles - compression and power stroke (two-stroke engine).

On the intake stroke inlet and fuel systems provide the formation of a fuel-air mixture. Depending on the design, the mixture is formed in intake manifold(central and distributed injection of gasoline engines) or directly in the combustion chamber ( direct injection petrol engines, injection diesel engines). When the intake valves of the gas distribution mechanism are opened, air or a fuel-air mixture is supplied into the combustion chamber due to the vacuum that occurs when the piston moves down.

On the compression stroke The intake valves close and the air-fuel mixture is compressed in the engine cylinders.

Stroke stroke accompanied by ignition of the fuel-air mixture (forced or self-ignition). As a result of ignition, a large amount of gases is formed, which put pressure on the piston and force it to move down. The movement of the piston through the crank mechanism is converted into rotational movement of the crankshaft, which is then used to propel the car.

On tact release the exhaust valves of the gas distribution mechanism open, and the exhaust gases are removed from the cylinders to the exhaust system, where they are cleaned, cooled and noise is reduced. The gases are then released into the atmosphere.

The considered principle of operation of the internal combustion engine makes it possible to understand why the internal combustion engine has a low efficiency - about 40%. At a particular moment in time, as a rule, useful work is performed in only one cylinder, while in the rest - providing cycles: intake, compression, exhaust.

INTERNAL COMBUSTION PISTON ENGINES

As mentioned above, thermal expansion is used in internal combustion engines. But how it is applied and what function it performs, we will consider using the example of the operation of a piston internal combustion engine. An engine is an energy-power machine that converts any energy into mechanical work. Engines in which mechanical work is created as a result of the conversion of thermal energy are called thermal. Thermal energy is obtained by burning any fuel. A heat engine in which part of the chemical energy of the fuel burning in the working cavity is converted into mechanical energy is called a reciprocating internal combustion engine.

WORKING PROCESSES IN PISTON AND COMBINED ENGINES CLASSIFICATION OF INTERNAL COMBUSTION ENGINES

An internal combustion engine is a piston heat engine in which the processes of fuel combustion, heat release and its transformation into mechanical work occur directly in the engine cylinder.

Internal combustion engines can be divided into:

gas turbines;

piston engines;

jet engines.

In gas turbines, fuel is burned in a special combustion chamber. Gas turbines having only rotating parts can operate at high speeds. The main disadvantages of gas turbines are low efficiency and operation of the blades in a high temperature gas environment.

In a piston engine, the fuel and air required for combustion are introduced into the engine's cylinder volume. The gases formed during combustion have a high temperature and create pressure on the piston, moving it in the cylinder. The translational movement of the piston through the connecting rod is transmitted to the crankshaft installed in the crankcase, and is converted into rotational movement of the shaft.

In jet engines, power increases with increasing speed. Therefore, they are common in aviation. The disadvantage of such engines is their high cost.

The most economical are piston-type internal combustion engines. But the presence of a crank mechanism, which complicates the design and limits the possibility of increasing the number of revolutions, is their disadvantage.

Internal combustion engines are classified according to the following main features:

1. according to the method of mixture formation:

a) engines with external mixture formation, when the combustible mixture is formed outside the cylinder. An example of such engines are gas and carburetor.

b) engines with internal mixture formation, when the combustible mixture is formed directly inside the cylinder. For example, diesel engines and engines with light fuel injection into the cylinder.

2. by type of fuel used:

a) engines running on light liquid fuels (gasoline, naphtha and kerosene);

b) engines running on heavy liquid fuel (solar oil and diesel fuel);

c) engines running on gas fuel (compressed and liquefied gases).

3. according to the method of ignition of the combustible mixture:

a) engines with ignition of a combustible mixture from an electric spark (carburetor, gas and light fuel injection);

b) compression ignition engines (diesels).

4. according to the method of implementation of the working cycle:

a) four strokes. For these engines, the duty cycle is completed in 4 piston strokes or 2 revolutions of the crankshaft;

b) two-stroke. For these engines, the duty cycle in each cylinder is completed in two strokes of the piston or in one revolution of the crankshaft.

5. according to the number and arrangement of cylinders:

a) single and multi-cylinder engines (two-, four-, six-, eight-cylinder, etc.)

b) single-row engines (vertical and horizontal);

c) two-row engines (V-shaped and with opposite cylinders).

6. by cooling method:

a) liquid-cooled engines;

b) air-cooled engines.

7. by appointment:

a) transport engines installed on cars, tractors, construction machines and other transport vehicles;

b) stationary engines;

c) special purpose engines.