What is the name of the diesel engine. Fuel supply system in diesel engines: varieties and differences

The number of vehicles grows every year, the characteristic sound of power unit which is given by its type. It is diesel engines that this publication will be devoted to, in which we will try to describe as much as possible their features, some performance characteristics and differences from gasoline engines.

Distinctive features of diesel units, such as: efficiency, high performance and fuel, which is cheaper, make this type of engine still in demand today. Latest Models diesel engines in terms of their noise level and environmental performance practically do not differ from their petrol counterparts, except that they are more economical and durable.

Design features

Structurally, diesel-powered motors are no different from gasoline ones, and have the same parts. Except that the valve elements of diesel engines are made more reinforced, otherwise they will not withstand the entire load. For comparison: the compression ratio of a diesel power unit is 19-24 units, which is twice as high as that of a gasoline one. For this reason, the diesel has a slightly larger dimensions and weight.

The noisy operation of this power unit is due to one of its features. The fact is that self-ignition of the mixture inside its cylinders occurs only when the pressure rises. Thanks to this, it is allowed to use cheap fuel in the engine (not to be confused with low-quality), and its operation on unenriched mixtures. Due to this, savings are achieved. Since the unit operates on raw mixtures, accordingly, its harmful emissions into the atmosphere are significantly reduced.

The only drawbacks of diesel engines are considered to be their noisy operation, accompanied by vibration, problems with starting in cold weather and less power in liters. But, such shortcomings are the prerogative of exclusively old engines, in modern diesel engines (due to their design features) these problems are excluded.

Diesel with direct injection

There are several designs of diesel engines that differ from each other in the structure of the combustion chamber. Units in which the combustion chamber is inseparable and the fuel is injected directly into the space above the piston are called direct injection engines. The piston plays the role of the combustion chamber.

Not so long ago, direct injection was used exclusively on low-speed diesel engines with an increased displacement. Such a measure was associated only with problems with fuel combustion, constant vibration and noisy work.

However, the situation changed with the advent of the fuel pump. high pressure controlled electronically, an innovative dual-level injection system and a solution to the problem of incomplete fuel combustion. Such measures made it possible to obtain stable operation of the unit already at 4500 rpm, made it more economical and quieter.

Diesel with separate chamber

Today, this type of diesel power unit is widely used in passenger cars. vehicles... Fuel in such an engine is injected into a separate chamber, not into the cylinder. A widespread model of a vortex chamber, which is located at the base of the cylinder block and through a special channel is connected to the cylinder in such a way that the air, compressed, gets into it, and then swirls inside like a vortex. This contributes to a good saturation of the mixture and increases its self-ignition, which occurs in the vortex chamber and then passes into the main one.

With this design of the motor, the pressure in its cylinders increases gradually, as a result of which the noise level of the unit is significantly reduced, and the speed increases. Almost 90% of diesel vehicles are equipped with vortex chamber engines.

Diesel fuel system

Perhaps this system is the most important part of diesel engine, for the most part characterizing its effectiveness. Its work consists in the metered supply of fuel at a certain pressure and at a certain time. Increased requirements for the accuracy of its operation, and the presence of high pressure inside the system make this unit of the diesel unit expensive and complex.

The fuel supply system consists of:

, which ensures the supply of diesel fuel to the engine injectors according to a strictly specified cycle, which depends on the operation of the unit and the forces applied by the driver to the accelerator pedal. The multi-mode injection pump combines the work of the main executive device, the function of which is to process driver commands, and automatic system control of the power unit.

By controlling the accelerator pedal, the driver does not decrease or increase the flow of the working mixture, but only sets the appropriate mode for the regulators, which independently adjust the fuel flow depending on the pressure, the number of revolutions, the position of the feed regulators, etc. Note that most diesel SUVs produced today are equipped with distribution type Injection pump.

Distribution injection pumps are mainly the prerogative of diesel engines installed on passenger cars. They are distinguished by correctly adjusted fuel supply and increased speed, due to which their stable operation is achieved on high revs... However, this type of fuel pump is too demanding on the quality of diesel fuel and its purity, since it lubricates the working surfaces of their parts.

Injectors of a diesel engine are no less important than a high-pressure fuel pump element of the fuel supply system, which, together with the fuel pump, provide an uninterrupted metered supply of the working mixture to the combustion chamber. The pressure in the fuel supply system depends on the angle of the nozzle, and the shape of the fuel torch, on which the entire correct sequence of self-ignition and combustion of the fuel depends, is given by the atomizer. There are two types of nozzles: multi-hole or font.

Injector operation in diesel unit due to conditions that are too difficult for her. This is due to the fact that the working movement of the nozzle needle is two times less than the engine speed, while the nozzle atomizer is constantly exposed to high temperatures and fuel explosions when it comes into contact with the combustion chamber. Accordingly, such an element must be made of durable and heat-resistant materials.

The fuel filter, although it is the simplest element in the diesel fuel supply system, still its absence will not be able to ensure the full operation of the engine. Its characteristics (filtration level and throughput capacity) must be selected in accordance with the type and power indicators of the power unit. In addition to filtering diesel fuel, the filter also acts as a water separator. For this, its design provides for a bottom drain closed with a plug. Often a hand pump is installed on the fuel filter, which is necessary to evacuate air from the system.

Rarely, but still there are electrically heated fuel filters, which at times makes it easier to start the unit in cold weather.

Features of starting diesel engines

Thanks to the preheating, a cold start of the diesel engine is possible. Active preheater so: inside the combustion chambers there are special electric heaters - glow plugs. At the moment the ignition is turned on, these elements provide instant heating of the combustion chambers, thus facilitating the process of self-ignition of the working mixture. The corresponding indicator in the passenger compartment signals the operation of the system.

As soon as the indicator goes out, the power unit is warmed up and ready to start. After starting the motor, the power supply continues to flow to the heating element for 15-20 seconds. This helps to stabilize the operation of the engine while it is still cold. Note that the pre-heater is able to provide a free start to the engine (provided it is in full serviceability and the availability of appropriate diesel fuel) at temperatures down to -30 degrees.

Turbocharged diesel

Effectively increase power diesel engine possible only with turbocharging. Thanks to him, a pump is supplied to the diesel cylinders by means of a pump more air, as a result of which the supply of the mixture increases, its combustion improves and the engine power increases. Since the exhaust gases of a diesel engine have a pressure 1.5-2 times greater than gasoline units, their turbocharger works more efficiently even at low speeds, which allows the turbocharged diesel engine to avoid failures in operation (so-called "turbo").

However, the turbodiesel is not without its drawbacks, which mainly consist in the imperfect design of the turbocharger. Its working resource rarely exceeds the mileage of 150 thousand km, which is much less than the resource of the unit itself.

Benefits of using the Common-Rail system

Thanks to the electronic fuel supply control system, diesel fuel is injected in two successive doses into the combustion chamber. First, a small portion is served, which is necessary to warm up the chamber, and after that, the main portion. Such a fuel metering system is very important for diesel power units, since it provides a smooth increase in pressure inside the combustion chambers, which is due to the lower noise of the engine and its stable operation.

The use of the Common-Rail system can reduce fuel consumption by 20%, while increasing the crankshaft torque by 25% when the engine is running at low speeds.

The video will show the structure and principle of operation of a diesel engine:

The video will tell you about the operation of modern diesel engines:

Diesel Engine - An internal combustion engine invented by Rudolf Diesel in 1897. The device of a diesel engine of those years made it possible to use oil, rapeseed oil, and solid types of combustible substances as fuel. For example, coal dust.

The principle of operation of the diesel engine of our time has not changed. However, motors have become more technologically advanced and demanding on fuel quality. Today, only high quality diesel fuel is used in diesel engines.

Diesel engines are distinguished by their fuel efficiency and good traction at low crankshaft speeds, therefore they are widely used for trucks mobiles, ships and trains.

Since the solution to the problem of high speeds (old diesel engines, with frequent use on high speeds quickly failed) the motors in question were often installed on passenger cars... Diesels designed for high-speed driving received a turbocharging system.

Diesel engine working principle

The principle of operation of a diesel type motor differs from gasoline engines. There are no spark plugs, and fuel is supplied to the cylinders separately from air.

The cycle of operation of such a power unit can be represented as follows:

a portion of air is supplied to the combustion chamber of the diesel engine;
the piston rises, compressing the air;
from compression, the air heats up to a temperature of about 800˚C;
fuel is injected into the cylinder;
Diesel fuel ignites, which leads to the lowering of the piston and the execution of the working stroke;
combustion products are removed by blowing through the outlet ports.

How a diesel engine works depends on its economy. In a working unit, a lean mixture is used, which saves the amount of fuel in the tank.

How a diesel engine works

The main difference between the design of a diesel engine and gasoline engines is the presence of a high-pressure fuel pump, diesel injectors and lack of spark plugs.

The general arrangement of these two types of power unit does not differ. Both have a crankshaft, connecting rods, pistons. At the same time, all elements of a diesel engine are reinforced, since the loads on them are higher.

Note: some diesel engines have glow plugs, which are mistaken by motorists for an analogue of spark plugs. In fact, this is not the case. Glow plugs are used to heat the air in cylinders in cold weather.

At the same time, the diesel engine is easier to start. Spark plugs in gasoline engines are used to ignite air-fuel mixture while the engine is running.

The injection system on diesel engines is made direct, when fuel enters the chamber directly, or indirect, when ignition occurs in the pre-chamber (vortex chamber, fore-chamber). This is a small cavity above the combustion chamber, with one or more holes through which air enters there.

Such a system contributes to better mixture formation, a uniform increase in pressure in the cylinders. Often it is in vortex chambers that glow plugs designed to facilitate cold start... When the ignition switch is turned, the process of heating the spark plugs is automatically started.

Pros and cons of a diesel engine

Like any other type of power unit, a diesel engine has positive and negative features. The "pluses" of a modern diesel engine include:

profitability;
good traction in a wide rpm range;
more resource than that of a gasoline analogue;
less harmful emissions.

Diesel is not without its drawbacks:

motors that are not equipped with glow plugs do not start well in frost;
diesel is more expensive and more difficult to maintain;
high requirements for the quality and timeliness of service;
high requirements for the quality of consumables;
more noise than gasoline engines.

Diesel turbocharged engine

The principle of operation of a turbine on a diesel engine practically does not differ from that on a gasoline engine. The bottom line is to pump additional air into the cylinders, which naturally increases the amount of incoming fuel. Due to this, a serious increase in motor power is noted.

The turbine device of a diesel engine also does not differ significantly from its gasoline counterpart. The device consists of two impellers, rigidly connected to each other, and a body that looks like a snail. There are 2 inlets and 2 outlets on the turbocharger casing. One part of the mechanism is built into the exhaust manifold, the second into the intake.

The scheme of work is simple: the gases coming out of a running motor spin the first impeller, which rotates the second. The second impeller, mounted in intake manifold, pumps atmospheric air into the cylinders. An increase in air supply leads to an increase in fuel supply and an increase in power. This allows the motor to pick up speed faster even at low revs.

Turboyama

During operation, the turbine can make up to 200 thousand revolutions per minute. It is immediately impossible to spin it up to the required rotation speed. This leads to the appearance of the so-called. turbo lags, when some time passes (1-2 seconds) from the moment you press the gas pedal to the start of intensive acceleration.

The problem is solved by finalizing the turbine mechanism and installing several impellers of different sizes. At the same time, small impellers spin up instantly, after which the elements catch up with them big size... This approach allows you to almost completely eliminate the turbo lag.

Turbines with variable geometry, VNT (Variable Nozzle Turbine) are also produced, designed to solve the same problems. At the moment, there are a large number of modifications of this type of turbine. The geometry correction also successfully copes with the reverse situation, when there are too many revolutions and air and it is necessary to slow down the impeller revolutions.

It was noticed that if mixture formation is used cold air, The efficiency of the motor increases up to 20%. This discovery led to the emergence of an intercooler, an additional element of turbines that increases efficiency.

Behind the turbine modern car must be properly cared for. The mechanism is extremely sensitive to quality engine oil and overheating. That's why lubricant it is recommended to change it at least after 5-7 thousand kilometers.

In addition, after stopping the car, the internal combustion engine should be left on for 1-2 minutes. This allows the turbine to cool down (it overheats when the oil circulation stops abruptly). Unfortunately, even with proper operation, the compressor resource rarely exceeds 150 thousand kilometers.

Note: the best solution to the problem of turbine overheating on diesel engines is to install a turbo timer. The device leaves the engine running for the required time after turning off the ignition. After the end of the required period, the electronics itself turns off the power unit.

The structure and principle of operation of the diesel engine make it an indispensable unit for heavy vehicles that need good traction"At the bottom." Modern diesel engines work with equal success in passenger cars, the main requirement for which: throttle response and acceleration time.

Difficult diesel maintenance is compensated by durability, economy and reliability in any situation.

Consider the design of a diesel engine and some of the differences from gasoline internal combustion engines.

Design features

Structurally, the unit is a fairly large-sized cylinder block made of a cast iron body. In its cavity there are nests bored at a certain angle with pressed-in sleeves (cylinders). The block has multiple sections around the sleeves that form a water cooling jacket. The constant circulation of the coolant in the cavities of the block head prevents the engine from overheating.

In its lower part, the block has a spherical bore (pillow) for mounting and fastening the crankshaft.

A large unit is considered to be a block head with cast seats for valve bushings.

The wedge drive of the water pump, air conditioner compressor, generator remains an integral part of the motor.

The main nodes include:

the mechanism of the connecting rod-piston group;
gas distribution mechanism;
crankcase and lubrication system.

It is these nodes, interacting with each other, that determine the characteristics of the power unit.

If we exclude the injection pump ( fuel pump high pressure), high nozzle pressure, reinforcement of individual parts, such as valves and pistons, then structural elements modern diesel and gasoline engines do not vary much.

Work process

The principle of operation of a diesel engine is to form and receive useful work from ignition fuel mixture... There is no mixing of diesel fuel with air and its supply to the combustion chamber with ignition from a spark, as is the case with petrol systems ignition. There is no ignition coil, distributor, candles, carburetor and other attributes of gasoline.

Answering the question of how a diesel engine works, let us note that in a diesel engine the mixing of fuel and air is carried out directly in the combustion chamber. That is, air is injected under the piston, which reaches a temperature of 700-800 ° C during the compression stroke. Having reached this temperature, the fuel pump is injected into the combustion chamber by means of nozzles into the combustion chamber. Injection under pressure, sometimes 30 atmospheres, leads to a reaction with heated air compression and instant autoignition of the resulting mixture. The process ends with pressure pushing the piston down towards BDC.

The system delivers a regulated dose of fuel through a high pressure pump. The presence of injectors and fuel filters predetermines the accuracy and smooth operation fuel equipment. The whole process is based on a high pressure fuel pump that supplies fuel based on the operating mode. The system is pressurized by means of plunger pairs. The injection pump drive is connected to crankshaft... By pressing the accelerator, the functions of regulating the fuel rate corresponding to the engine speed are performed.

Injector, fuel filter

Together with the high-pressure fuel pump, injectors are an extremely important unit of the fuel system. Their function is to supply a specific dose of fuel to the combustion chamber. The pressure at which the injector opens is equal to the value required to maximally crush the diesel and create fuel mist.

At the end of the nozzles, in difficult temperature conditions, a needle atomizer works, which forms a torch contour. The injection circuit is essential for fast, complete combustion. Heavy duty is due to their constant presence in the area of the combustion chamber. Based on this, the nozzle sprayers are made of heat-resistant materials on machines of the highest processing accuracy. For soft, quiet operation, a meager dose of fuel is first fed into the chamber. It only heats up the air in the chamber. At a given moment, the main dose is injected. These actions, by means of electronics, allow a smooth increase in pressure, creating conditions for the complete combustion of the fuel-air mixture.

Into the prerogative fuel filter includes the possibility fine cleaning fuel. But the main function is based on the separation of water from the fuel. Therefore, the filter needs to periodically remove the water sediment through the drain cock.

An electric heating system helps to prevent critical cooling with subsequent waxing of the fuel, which contributes to a quick start of a cold engine.

Start-up, turbocharging

Cold start of the diesel engine is facilitated by the preheating system, for which there are specially placed plugs in the combustion chamber with a glow function up to 900 ° C. Information about the degree of heating is reported warning light on dashboard(swirling spiral). As the engine runs steadily, the spark plug automatically extinguishes. In some cars, the spark plugs are turned off when the starter is energized.

Turbocharging system is focused on increasing power and stability in all modes ICE operation... That is, the turbine compressor supplies an excess portion of air under the piston, thereby increasing the engine power. But the long life of the compressor must be maintained high quality engine oil.

Turbocharging system design

Injection system

Most effective system fuel injection is considered Common rail... The principle of the system is that fuel is accumulated in the main rail, from which it flows directly into the injector. And this is the way to save diesel fuel, low noise from the working stroke and exhaust gases. During a cycle of operation, the device performs two stages of injection. The smallest amount of fuel in the beginning and the main dose to get the most out of combustion.

These advantages have led to the use of this injection system on almost every truck. diesel car and in most civilian models.

The pump-injector system involves the installation of one injector for each cylinder. The device differs from Common Rail in its high injection pressure. The starting point is considered to be a high capacity of transport up to 20%, efficiency, low toxicity of mining. In both cases, the control functions are carried out by the engine management system via magnetic solenoids.

An additional system, used in conjunction with diesel internal combustion engines, is designed to reduce the toxicity of exhaust gases. Catalytic converter is designed to burn the remains of gas particles in the particulate grid. But this is already from the field of mining regeneration, which is widely used on gasoline internal combustion engines. The only peculiarity is that when paired with an internal combustion engine running on diesel fuel, the system is especially effective and allows you to achieve impressive indicators of the environmental friendliness of diesel internal combustion engines.

Diesel engines have managed to go through a long and successful path of development from inefficient and environmentally polluting units of the early twentieth century to super economical and completely silent, which are now installed on a good half of all cars produced. But, despite such successful modifications, general principle their actions, distinguishing diesel engines from gasoline ones, remained the same. We will try to consider this topic in more detail.

What are the main differences between diesel and gasoline engines?

It is already clear from the name itself that diesel engines do not run on gasoline, but on diesel fuel, which is also called diesel fuel, diesel fuel or simply diesel. Go into all the details chemical processes We will not distill oil, we will only say that both gasoline and diesel are produced from oil. During distillation, oil is divided into different fractions:

gaseous - propane, butane, methane;
sledges (short chains of carbohydrates) - used for the production of solvents;
gasoline is an explosive and quickly evaporating transparent liquid;
kerosene and diesel are liquids with a yellowish tint and a more viscous structure than gasoline.

That is, diesel fuel is produced from heavier fractions of oil, its most important indicator is flammability, determined by the cetane number. Diesel fuel is also characterized by a high sulfur content, which, however, they are trying to reduce by all means so that the fuel meets environmental standards.

Like gasoline, diesel is divided into different types depending on temperature conditions:

summer;
winter;
arctic.

It is also worth noticing that diesel fuel They are produced not only from oil, but also from various vegetable oils - palm, soybean, rapeseed, etc., mixed with technical alcohol - methanol.

However, the fuel being poured is not the main difference. If we look at the gasoline and diesel engines "in a cut", then we will not notice any difference visually - the same pistons, connecting rods, crankshaft, flywheel and so on. But there is a difference and it is very significant.

Diesel engine working principle

Unlike gasoline engines, in a diesel engine, an air-fuel mixture is ignited according to a completely different principle. If in gasoline - both in carburetor and injection - engines, the mixture is first prepared, and then ignited with the help of a spark from the spark plug, then in a diesel engine air is pumped into the combustion chamber of the piston, then the air is compressed, warming up to temperatures of 700 degrees, and at this moment, fuel enters the chamber, which immediately explodes and pushes the piston down.

Diesel engines are four-stroke. Let's take a look at each beat:

First stroke - the piston moves down, the intake valve opens, thereby air enters the combustion chamber;
Second stroke - the piston begins to rise, the air begins to compress and heat up under pressure, it is at this moment that diesel fuel is injected through the nozzle, and it ignites;
The third cycle is a worker, an explosion occurs, the piston begins to move down;
Fourth measure - opens Exhaust valve and all exhaust gases go to the exhaust manifold or to the turbine pipes.

Of course, all this happens very quickly - several thousand revolutions per minute, very well-coordinated work and adjustment of all units - pistons, cylinders, camshaft, crankshaft connecting rods, and most importantly sensors - which must transmit hundreds of pulses to the CPU per second for instant processing and calculation required volumes air and diesel fuel.

Diesel engines give out a greater efficiency, which is why they are used on trucks, combines, tractors, military equipment etc. Diesel fuel is cheaper, but it should be noted that the engine itself is more expensive to operate, because the compression level here is almost two times higher than in gasoline, accordingly, pistons of a special design are needed, and all the components, parts and materials used are reinforced, that is, they cost expensive.

Also very strict requirements are applied to fuel supply and exhaust gas removal systems. Not a single diesel engine can work without a high-quality and reliable high-pressure fuel pump - a high-pressure fuel pump. It ensures the correct supply of fuel to each injector. In addition, turbines are used on diesel engines - with their help, exhaust gases are reused, thereby increasing engine power.

The diesel engine also has a number of problems:

increased noise;
more waste - the fuel is more oily, so you need to regularly replace filters, monitor the exhaust;
problems with starting, especially cold, a more powerful starter is used, the fuel thickens quickly when the temperature drops;
repairs are expensive, especially for fuel equipment.

In a word - to each his own, diesel engines are characterized by more power are associated with powerful SUVs and trucks. For a simple city dweller who commutes to work - from work and on weekends leaves the city, a low-power gasoline engine is enough.

A video showing the whole principle of operation of a diesel internal combustion engine

The diesel engine's features such as economy and high torque make it the preferred option. Modern diesel engines are close to gasoline engines in terms of noise, while retaining the advantages in efficiency and reliability.

Design and structure

By design, a diesel engine does not differ from a gasoline engine - the same cylinders, pistons, connecting rods. True, the valve parts are reinforced to handle high loads - after all, the compression ratio of the diesel engine is much higher (19-24 units versus 9-11 units) gasoline engine). This explains the large weight and dimensions of a diesel engine in comparison with a gasoline one.

The fundamental difference lies in the methods of forming a mixture of fuel and air, its ignition and combustion. In a gasoline engine, the mixture is formed in the intake system, and in the cylinder it is ignited by a spark plug. In a diesel engine fuel and air are supplied separately... First, air enters the cylinders. At the end of the compression stroke, when it heats up to a temperature of 700-800 ° C, diesel fuel is injected into the combustion chamber under high pressure, which spontaneously ignites almost instantly.

Mixing in diesel engines takes place in a very short period of time. To obtain a combustible mixture capable of quickly and completely combusting, it is necessary that the fuel is atomized into as small particles as possible and that each particle has a sufficient amount of air for complete combustion. For this purpose, fuel is injected into the cylinder by a nozzle at a pressure several times higher than the air pressure during the compression stroke in the combustion chamber.

In diesel engines, unseparated combustion chambers are used. They represent a single volume limited by the bottom piston 3 and cylinder head and wall surfaces. For better mixing of fuel with air, the shape of the unseparated combustion chamber is adapted to the shape of the fuel flares. Recess 1, made in the piston crown, contributes to the creation of a vortex air movement.

Finely atomized fuel is injected from nozzles 2 through several holes directed to certain places of the recess. In order for the fuel to completely burn out and the diesel engine has the best power and economic performance, fuel must be injected into the cylinder before the piston reaches TDC.

Self-ignition is accompanied by a sharp increase in pressure - hence the increased noise and rigidity of work. This organization of the workflow allows you to work on very lean mixtures, which determines high efficiency. Better environmental performance too - when running on lean mixtures, emissions harmful substances less than gasoline engines.

The disadvantages include increased noise and vibration, less power, difficulties in cold starting, problems with winter diesel fuel. With modern diesel engines, these problems are not so obvious.

Diesel fuel must meet certain requirements. The main indicators of fuel quality are purity, low viscosity, low temperature self-ignition, high cetane number(not lower than 40). The higher the cetane number, the shorter the autoignition delay period after the moment it is injected into the cylinder and the engine runs softer (no knocking).

Diesel engine types

There are several types of diesel engines, the difference between which lies in the design of the combustion chamber. In diesel engines with an unseparated combustion chamber- I call them diesel engines with direct injection - fuel is injected into the space above the piston, and the combustion chamber is made in the piston. Direct injection it is used on low-speed engines of large displacement. This is due to the difficulties of the combustion process, as well as increased noise and vibration.

Thanks to the introduction of high-pressure fuel pumps (TNVD) with electronic control, two-stage fuel injection and optimization of the combustion process, it was possible to achieve stable operation of a diesel engine with an unseparated combustion chamber at speeds up to 4500 rpm, improve efficiency, reduce noise and vibration.

The most common is another type of diesel - with a separate combustion chamber... Fuel is injected not into the cylinder, but into an additional chamber. Usually, a vortex chamber is used, made in the cylinder head and connected to the cylinder by a special channel so that when compressed, air entering the vortex chamber swirls intensively, which improves the process of self-ignition and mixture formation. Self-ignition starts in the vortex chamber and then continues in the main combustion chamber.

With a separate combustion chamber, the rate of pressure rise in the cylinder decreases, which contributes to a decrease in noise and an increase in maximum speed... Such engines make up the majority of those installed on modern cars.

Fuel system device

The most important system is the fuel supply system. Its function is to supply a strictly defined amount of fuel at a given moment and at a given pressure. High fuel pressure and precision requirements make the fuel system complex and expensive.

The main elements are: a high pressure fuel pump (injection pump), injectors and a fuel filter.

Injection pump

The injection pump is designed to supply fuel to the injectors according to a strictly defined program, depending on the engine operating mode and the driver's actions. At its core, a modern injection pump combines the functions of a complex system automatic control the engine and the main actuator, which fulfills the driver's commands.

By pressing the gas pedal, the driver does not directly increase the fuel supply, but only changes the operating program of the regulators, which themselves change the supply according to strictly defined dependences on the speed, boost pressure, position of the regulator lever, etc.

On modern cars the distribution type injection pump is used. Pumps of this type are widely used. They are compact, characterized by high uniformity of fuel flow through the cylinders and excellent operation at high speeds due to the speed of the regulators. At the same time, they make high demands on the purity and quality of diesel fuel: after all, all their parts are lubricated with fuel, and the gaps in precision elements are small.

Injectors.

Another important element of the fuel system is the injector. Together with the high-pressure fuel pump, it supplies a strictly metered amount of fuel to the combustion chamber. The adjustment of the opening pressure of the injector determines operating pressure v fuel system, and the type of atomizer determines the shape of the fuel flame, which is essential for the autoignition and combustion process. Usually, nozzles of two types are used: with a font or multi-hole distributor.

The injector on the engine works in difficult conditions: the nozzle needle reciprocates at half the engine speed, with the nozzle in direct contact with the combustion chamber. Therefore, the nozzle atomizer is manufactured from heat-resistant materials with particular precision and is a precision element.

Fuel filters.

The fuel filter, despite its simplicity, is the most important element of a diesel engine. Its parameters, such as filtering fineness, throughput, must strictly correspond to a specific type of engine. One of its functions is the separation and removal of water., which is usually the bottom drain plug... A manual priming pump is often installed on the top of the filter housing to remove air from the fuel system.

Sometimes an electric fuel filter heating system is installed, which makes it somewhat easier to start the engine, preventing clogging of the filter with paraffins formed during the crystallization of diesel fuel in winter conditions.

How does the launch take place?

Cold start of the diesel engine is provided by the preheating system. For this, electric heating elements- glow plugs. When the ignition is turned on, the candles heat up to 800-900 ° C in a few seconds, thereby heating the air in the combustion chamber and facilitating self-ignition of the fuel. The driver in the cab is signaled by a warning lamp about the system operation.

Extinction control lamp indicates readiness for launch. The power supply from the spark plug is removed automatically, but not immediately, but 15-25 seconds after starting, in order to ensure stable operation of an unheated engine. Modern systems pre-heating ensure easy start-up of a serviceable diesel engine up to a temperature of 25-30 ° C, of course, provided that the oil and diesel fuel are suitable for the season.

Turbocharging and Common-Rail

Turbocharging is an effective means of increasing power. It allows additional air to be supplied to the cylinders and, as a result, increases power. The exhaust gas pressure of a diesel engine is 1.5-2 times higher than that of a gasoline engine, which allows the turbocharger to provide effective boost from the most low revs, avoiding the failure characteristic of gasoline turbo engines - "turbo lags".

Computer control of the fuel supply made it possible to inject it into the combustion chamber of the cylinder in two precisely metered portions. First comes a tiny dose, only about a milligram, which, when burned, raises the temperature in the chamber, followed by the main "charge". For a diesel engine - an engine with compression ignition - this is very important, since the pressure in the combustion chamber increases more smoothly, without a "jerk". As a result, the motor runs smoother and quieter.

As a result, in diesel engines with the Common-Rail system, fuel consumption is reduced by 20%, and the torque at low crankshaft speeds increases by 25%. Also, the content of soot in the exhaust is reduced and the noise of the engine is reduced.