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

For about a hundred years, everywhere in the world, the main power unit on cars and motorcycles, tractors and combines, and other equipment has been 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 of various types of internal combustion engines and its main auxiliary systems.

The content of the article:

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 crankshaft. Piston engines are divided, in turn, into
• carburetor, in which the air-fuel mixture is 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 ignition 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 a rotor of a special shape 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 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, cars rotary piston engines only Mazda makes. 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.

Internal combustion engine device

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 motion to the crankshaft;
• gas distribution mechanism, which is designed to ensure the timely opening / closing of valves for intake / exhaust 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.

The operation of a piston internal combustion engine 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 measures that repeat in a certain sequence.

According to the number of strokes within one working cycle, internal combustion engines are divided 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. Once it reaches its bottom dead center(BDC) and proceeds to move upwards, 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.

Opens at this time Exhaust valve 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.

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

- The principle of operation of a four-stroke engine

Four-stroke internal combustion engines are deprived of these shortcomings, which, in various versions, 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

- Ignition system

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. Components ignition systems are:

• Power supply. During engine start, this is accumulator battery, and during its operation - the generator.
• Switch, or ignition switch. It used to be mechanical, but in recent years it has become more and more electrical. 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 air filter. And that's it. The composition of the intake system of modern cars, tractors and other equipment includes:

• air intake. It is a branch pipe of a form convenient for each particular engine. Through it, atmospheric air is sucked into the engine, through the difference in pressure in the atmosphere and in the engine, where vacuum occurs when the pistons move.
• Air filter. This is a consumable product designed to clean the air entering the motor from dust and solid particles, their retention 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 the air flow the desired distribution, special intake flaps and a vacuum booster are used.

- Fuel system

The fuel system, or the power supply system of the internal combustion engine, is "responsible" for uninterrupted fuel supply to form a fuel-air mixture. The 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 - 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

The purpose of the ICE lubrication system is 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 system

exhaust internal combustion engine system serves for removing spent gases And noise reduction motor work. In modern technology, the exhaust system consists of the following parts (in order of exhaust gases leaving 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 on mopeds, scooters and cheap motorcycles is still applied 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.

The principle of operation of a four-stroke internal combustion engine
This principle and cyclicality is called the "OTTO Cycle"

look...
Inline internal combustion engine

V-shaped internal combustion engine

Boxer internal combustion engine

Rotary piston internal combustion engine

Scheme of the ignition system of an internal combustion engine


A. Wire to spark plug
B. Distributor cover
C. Slider
D. high voltage wire ignition coils
E. Distributor housing
F. Distributor cam
G. Ignition pulse sensor
H. Ignition control unit
I. Ignition coil
J. Candles

WANKEL ROTARY PISTON ENGINE

Advantages and disadvantages of modern RPD compared to traditional internal combustion engines

Advantages:
30 - 40% fewer parts
Significantly less specific gravity. Compact design. Complete
mass balance. Lack of gas distribution
mechanism. The engine is high-torque and very elastic, which allows less frequent
change gears. Easily upgradeable for
work on hydrogen.

Flaws:
In a stretched RPD combustion chamber, it is difficult to create turbulent
high intensity movement for fast and complete combustion
combustible mixture, which worsens the efficiency of the engine and
complicates the fight against harmful emissions. Unable to create
diesel RPD. Greater oil consumption (to lubricate the combustion chamber)

1. The rotor rotates on a longitudinal shaft, the shaft has an eccentric,
in fact, the rotor is spinning on it, and the gear is present for
transmission desired phase rotor when rotating on an eccentric.
2. The rotation of the rotor on the shaft is lubricated, there is an oil pump in the RPD
And oil pan. The angular surface of the rotor in the combustion chamber
is not lubricated, it uses a gasket material made of
teflon, which has the function of sealing and sliding, but on
side surfaces of the rotor are supplied with oil, which is inevitable
enters the combustion chamber, therefore, the environmental friendliness of the RPD cannot
to talk...

ICE with piston "Swing"

The piston of the new motor, cut in half, clearly shows
one of its main advantages. The blue inserts represent
coolant that is supplied to the piston through its
reference axis

Technical terms

DOHC - Double Over-Head Camshaft (Two Overhead Camshafts)
SOHC - Single Over-Head Camshaft
OHC - Over-Head Camshaft
Twin Cam - Twin Cam - NOT TWO CAMS!
(If the engine uses two valves with a single and
simultaneous function, at the air inlet or outlet
exhaust gases, while both single-function valves,
simultaneously driven by their own cam
camshaft. Two valves - "twin", plus two single-phase
camshaft cams and are the "TWIN CAM" system.
This system is used only in engines with a "DOHC" system)

HETC - High Efficiency Twin Cam - (Double cam with high efficiency,
Twin Cam system with variable valve timing)
Supercharger - Supercharger (Roots compressor, mechanical supercharger, which
It is driven by the crankshaft through a drive belt.
Power increase system, without engine speed increase)
EFI - Electronic Fuel Injection - ( electronic injection fuel)
GDI - Gasolin Direct Injection - (gasoline direct injection)
MPI - Multi Point Injection - ( distributed injection fuel)
Intercooler - Intermediate air cooling.
4WD - 4 Wheel Drive - (4 wheel drive)
4WS - 4 Wheels Swivel - (4 swivel wheels) All 4 wheels are steered
when turning, and rear wheels at speeds up to 35 km/h. turn around
in the opposite direction to the front, and at a higher speed in the same direction.
AWD- All wheel Drive - (All wheel drive)
FWD - Four Wheel Drive - (Four wheel drive)

GT (Gran Turismo)
Literally translated as "big trip"
GT car class are high speed cars like
rule with a 2- or 4-seater coupe body designed for
roads common use. The abbreviation GT is also
racing class designation in motor racing.
There is also an incorrect broad interpretation of the term,
according to which all sports cars are included in the GT category
shape.

GTi - Gran Turismo Iniezione (vehicle equipped with fuel injection)
GTR-Gran Turismo Racer
GTO - Gran Turismo Omologato (Vehicle eligible for GT racing)
GTS-Gran Turismo Spider
GTB - Gran Turismo Berlinetta (coupé with long bonnet and gently sloping roof)
GTV - Gran Turismo Veloce (Designation for uprated GT cars)
GTT-Gran Turismo Turbo
GTE - Einspritzung German for fuel injection (this is the German analogue of the GTi index)
GTA - Gran Turismo Alleggerita (Light GT car)
GTAm modified lightened car
GTC - Gran Turismo Compressore/Compact/Cabriolet/Coupe
GTD-Gran Turismo Diesel
HGT-High Gran Turismo

BEAMS (Breakthrough Engine with Advanced Mechanism System)
The latest engine with an improved system of mechanisms
BEAMS is a whole family (or generation) of engines
(absolutely all types) with installed mechanical
gas distribution mechanisms with the possibility of changing
phases of any design: VVT, VTEC, MIVEC, Vanos or any
others. BEAMS is a general automotive term referring to
only to Toyota, but also to Subaru, BMW, Mercedes, Audi, Honda and others.
The next generation of engines was named Dual BEAMS and
applied to internal combustion engines with installed gas distribution
mechanisms VVT-i, iVTEC, Double Vanos, Bi-Vanos and others with
additional electronic control, except for mechanical
drive.

CVVT (Continuous variable valve timing)
Variable valve timing system
Alfa Romeo - Double continuous variable valve timing. CVVT is used on intake and exhaust
BMW - VANOS/Double VANOS. First used in 1993 for the BMW 3 and 5 series
PSA Peugeot Citro?n - Continuous variable valve timing (CVVT)
Chrysler - dual Variable Valve Timing (dual VVT)
Daihatsu - Dynamic variable valve timing (DVVT)
General Motors - Continuous variable valve timing (CVVT)
Honda - i-VTEC = VTEC. It was first used in 1990 on Civic vehicles and CRX
Hyundai - Continuous variable valve timing (CVVT) - debuted in 2.0 L Beta I4 engine
in 2005 in the car "Elantra" and "Kia Spectra", was also applied
in a new engine (Alpha II DOHC) in 2006 for Accent \ Verna, Tiburon and Kia cee'd cars
MG Rover - Variable Valve Control (VVC)
Mitsubishi - Mitsubishi Innovative Valve timing Electronic Control (MIVEC). First used in 1992 in the 4G92 engine
Nissan - Continuous Variable Valve Timing Control System (CVTCS)
Toyota - Variable Valve Timing with intelligence (VVT-i), Variable Valve Timing with Lift and Intelligence (VVTL-i)
Volvo - Continuous variable valve timing (CVVT)

An internal combustion engine with a rotating cylinder
intake and exhaust valve function.



four-stroke engine, which does not have the usual valves and
their entire drive system. Instead, the British forced to work
the gas distributor itself is the working cylinder of the engine, which in
motors RCV rotates around its own axis. The piston at the same time
makes exactly the same movements as before. And here are the walls
cylinder rotate around the piston (the cylinder is fixed inside
motor on two bearings). A branch pipe is arranged from the edge of the cylinder,
which alternately opens to the inlet or outlet
window. A sliding seal is also provided here, working
similar to piston rings - it allows the cylinder
expand when heated, without losing tightness. lead
cylinder in rotation, only three gears: one on the cylinder, one
on the crankshaft and one - intermediate. Naturally, the speed
rotation of the cylinder - half the revolutions of the crankshaft.

The key part of the cylinder rotation drive is the intermediate
combination gear.

A two-stroke engine is a piston internal combustion engine in which the working process in each of the cylinders takes place in one revolution of the crankshaft, that is, in two piston strokes. The compression and stroke strokes in a two-stroke engine occur in the same way as in a four-stroke engine, but the processes of cleaning and filling the cylinder are combined and are carried out not within individual strokes, but in a short time, when the piston is near the bottom dead center, using auxiliary unit- purge pump.
Due to the fact that in a two-stroke engine, with an equal number of cylinders and the number of revolutions of the crankshaft, the working strokes occur twice as often, the liter power of two-stroke engines is higher than that of four-stroke engines - theoretically twice, in practice 1.5-1.7 times, since part of the useful stroke of the piston is occupied by gas exchange processes, and the gas exchange itself is less perfect than in four-stroke engines.
Unlike four-stroke engines, where the displacement of exhaust gases and the suction of a fresh mixture is carried out by the piston itself, in two-stroke engines, gas exchange is carried out by supplying to the cylinder working mixture or air (in diesel engines) under pressure created by a purge pump, and the gas exchange process itself is called purge. During the scavenging process, fresh air (mixture) forces combustion products out of the cylinder into the exhaust organs, taking their place.
According to the method of organizing the movement of purge air flows (mixtures), two-stroke engines are distinguished with contour and direct-flow purge.

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 of various capacities were produced. 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 who received a patent for the invention of his gas engine model 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 the more complete expansion of the combustion products, the efficiency of 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-and-rod transmission 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

• 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 oil).

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

Working cycle four-stroke engines Internal combustion takes two complete revolutions of the crank, consisting of four separate strokes:

1. intake,
2. charge compression,
3. working stroke and
4. 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 motors with electromagnetic control valves (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 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 provide a complete separation 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 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 diesels with three star-shaped 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).

see also

• Philippe Lebon - French engineer who received a patent in 1801 for an internal combustion engine that compresses a mixture of gas and air.
• Rotary engine: designs and classification
• Rotary piston engine (Wankel engine)

Notes

Links

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

On our roads, most often you can find cars that consume gasoline and diesel fuel. The time for electric cars has not yet come. Therefore, consider the principle of operation of an internal combustion engine (ICE). Its distinctive feature is the transformation of explosion energy into mechanical energy.

When working with gasoline power plants, there are several ways to form the fuel mixture. In one case, this happens in the carburetor, and then it's all fed into the engine cylinders. In another case, gasoline is injected through special nozzles (injectors) directly into the manifold or combustion chamber.

To fully understand the operation of an internal combustion engine, it is necessary to know that there are several types modern motors that have proven their effectiveness in the work:

• gasoline engines;
• engines consuming diesel fuel;
• gas installations;
• gas-diesel devices;
• rotary options.

The principle of operation of these types of internal combustion engines is almost the same.

ICE cycles

Each has fuel that explodes in the combustion chamber, expands and pushes a piston mounted on a crankshaft. Further, this rotation is transmitted to the wheels of the car through additional mechanisms and nodes.

As an example, we will consider gasoline four stroke motor, because it is the most common power plant in cars on our roads.

So you:

1. the intake opening opens and the combustion chamber is filled with the prepared fuel mixture
2. the chamber is sealed and its volume decreases in the compression stroke
3. the mixture explodes and pushes the piston, which receives an impulse of mechanical energy
4. the combustion chamber is freed from combustion products

Each of these stages of the work of the internal combustion engine has its own, several simultaneous processes take place. In the first case, the piston is in its lowest position, while all valves that inlet fuel are open. The next stage begins with the complete closing of all holes and the movement of the piston to the maximum upper position. At the same time, everything is compressed.

Reaching the extreme top position of the piston again, voltage is applied to the candle, and it creates a spark, igniting the mixture for an explosion. The force of this explosion pushes the piston down, while the outlet openings open and the chamber is cleared of residual gas. Then everything repeats.

Carburetor operation

The formation of the fuel mixture in the cars of the first half of the last century took place with the help of a carburetor. To understand how an internal combustion engine works, you need to know that automotive engineers the fuel system was designed in such a way that an already prepared mixture was fed into the combustion chamber.

Carburetor device

The carburetor was engaged in its formation. He mixed gasoline and air in the right proportions and sent it all to the cylinders. This relative simplicity of system design allowed him to for a long time remain an indispensable part of gasoline units. But later, its shortcomings began to prevail over the merits and did not meet the increasing requirements for cars in general.

Disadvantages of carburetor systems:

• it is not possible to provide economical modes with sudden changes in driving modes;
• exceeding limits harmful substances in exhaust gases;
• low power of cars due to inconsistency of the prepared mixture with the condition of the car.

They tried to compensate for these shortcomings by direct supply of gasoline through the injectors.

The operation of injection engines

The principle of operation of the injection engine is direct injection gasoline into the intake manifold or combustion chamber. Visually, everything is similar to the work diesel plant when the feed is metered and only into the cylinder. The only difference is that the injection units spark plugs installed.

Injector design

Stages of work gasoline engines with direct injection do not differ from the carburetor version. The difference is only in the place where the mixture is formed.

Due to this design option, the advantages of such engines are provided:

• an increase in power up to 10% with similar technical characteristics with a carburetor;
• noticeable savings in gasoline;
• improvement of environmental performance in terms of emissions.

But with such advantages, there are also disadvantages. The main ones are maintenance, maintainability and customization. Unlike carburetors, which can be disassembled, assembled and adjusted independently, injectors require special expensive equipment and a large number of different sensors installed in the car.

Fuel injection methods

In the course of the evolution of the fuel supply to the engine, this process has been constantly approaching the combustion chamber. In the most modern internal combustion engines, the point of supply of gasoline and the place of combustion have merged. Now the mixture is no longer formed in the carburetor or intake manifold, but is injected directly into the chamber. Consider all options for injection devices.

Single point injection option

The simplest design option looks like fuel injection through a single nozzle into the intake manifold. The difference with the carburetor is that the latter delivers the finished mixture. In the injection version, fuel is supplied through the nozzle. The benefit is to save on costs.

Single point fuel supply option

This method also forms the mixture outside the chamber, but here sensors are involved that provide supply directly to each cylinder through the intake manifold. This is a more economical option for using fuel.

Direct injection into the chamber

This variant so far uses the possibilities of the injector design most effectively. The fuel is directly sprayed into the chamber. Due to this, the level of harmful emissions is reduced, and the car receives, in addition to greater gasoline savings, increased power.

The increased degree of system reliability reduces the negative factor regarding maintenance. But such devices need high-quality fuel.

The internal combustion engine, or internal combustion engine, is the most common type of engine found in automobiles. 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?

An internal combustion engine is a type of heat engine that converts part of the chemical energy obtained from the combustion of fuel into mechanical energy that 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 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 prevent the combustible mixture from entering 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 vehicles that burn oil are equipped with older engines and piston rings no longer provide adequate sealing.

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

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

8. The crankcase is located around the 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 considered the purpose and design of the internal combustion engine. 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 the intake valve. Then it is compressed and ignited by a spark from a spark plug. When the fuel burns, a very high temperature is generated in the chamber, which leads to an overpressure in the cylinder. This causes the piston to move towards the "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 at its top dead center. 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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