The principle of operation of the diesel engine. Everything about diesel engine or "Why diesel?" Diesel engine functions

Did you think of dear motorists think about why economical Europeans most often acquire cars with diesel engines? After all, the standard of living and per capita income in Europe allows people not to think about the cost of fuel. But in spite of the normal welfare of the citizens of Europe, they still continue to buy cars with diesel engines most often. And the reason here is the best not only in fuel economy. Because of the savings, the pedantic Europeans would never have mastedly buy diesel cars. In fact, in the European Union itself is associated with a number of other benefits that have these diesel vehicles, if they compare them with gasoline analogues. Let's find friends with us (you) learn in detail, and what advantages in addition to fuel economy there is diesel engines.

1. Diesel engines are more economical.

As we have long known, the most important and significant advantage of any diesel engine compared to gasoline counterparts is its smaller. The low flow rate of the diesel unit is associated with its feature of the transformation of this diesel fuel into energy. For example, such a diesel power unit becomes more efficiently burning fuel (fuel), which allows it to receive about 45 - 50% of all the energy from one volume of the fuel. The gasoline engine receives from the same volume of approximately 30% of energy. That is, 70% of gasoline burns just wasted !!!

In addition, diesel engines have a higher compression ratio than gasoline motors. And since the time of this compression is influenced by the time of fuel ignition, then it turns out that the higher the degree of compression, the greater the efficiency is the engine.

Also, all modern diesel motors due to the lack of throttle on the intake manifold are more effective, which was usually used and used today in all gasoline cars. This allows diesellers (motors) to avoid the loss of precious energy associated with air absorption, which is necessary to influence fuel in gasoline engines.

2. Diesel engines are more reliable than gasoline.

Over the past 50 years, diesel engines have proven themselves as more reliable than their petoline juice. The main feature of this diesel unit is the absence of an ignition system itself, which runs from high voltage. As a result, it turns out that in the car with a diesel engine there are no radio frequency interference from the high voltage line, which often become perpetrators of the car electronics.

It is also believed that most of the internal components of the diesel engine have a longer service life and this is true. And all because of a higher compression, where the components of such a diesel power unit are already initially more durable.

It is for this important reason in the world there are a lot of diesel cars with mileage about and not so much with the same mileage of gasoline cars.

There is a truth one substantial minus in diesel engines, which previously did not give peace to all fans of powerful cars. The case is next, in the diesel engines of the old generation for each liter of the volume of the motor was (issued) very small power. But our happiness engineers solved this problem with the appearance of machines with turbines at the car market. As a result, almost all modern diesel engines are equipped with turbines today, which allow them to be equal in power (and sometimes even exceed) with gasoline analogues. Including with the development of new technologies in modern diesel engines, engineers managed to minimize almost all its disadvantages, which have proven these diesel engines for a long time.

3. The diesel engine itself automatically burns fuel.

Another major advantage of all diesel engines is that diesel cars are automatically in themselves, burning fuel in itself without spending actually no excess energy. We will remind your readers the following, despite the fact that the diesel engine uses a four-stroke cycle (inlet, compression, combustion and exhaust), the burning of diesel fuel is happening, as it were, spontaneously directly inside the engine from a large compression. For the same fuel burning, the ignition candles are needed (necessary), which are constantly under high voltage and provide a spark, which ignites gasoline in the combustion chamber.

In diesel engines in the Ignition Candle, there is no need, and he also does not need both high-voltage wires, etc. components. For this reason, the costs of the maintenance of cars with diesel units are significantly reduced if they are compared with the same gasoline vehicles in which periodically need to change the spark plugs, high-voltage wires and associated other components.

4. The cost of diesel fuel is comparable to the cost of the same gasoline, or even lower.

Despite the fact that in Russia the cost of diesel fuel is on the same level as the price of gasoline, it should be noted that the cost of diesel fuel in many countries of the world including in Europe in comparison with our country is noticeably below than the same gasoline. That is, it turns out that in addition to the reduced fuel consumption, the data owners of diesel cars in other countries of the world spend much less money on diz-fuel than the remaining owners of gasoline vehicles.

But even with the condition that in our country, the diesel engine is also like gasoline (or even more expensive), then the advantage of the same efficiency of these diesel cars is obvious to many. After all, the reserve of the machine running on a full-filled diz-fuel tank is much larger than on the same car equipped with a gasoline power unit.

5. Lower cost of ownership.

With such an advantage (possession of a car with a gasoline engine), it is difficult to argue, since in certain cases, the cost of maintenance and repair of diesel cars can significantly exceed the cost (maintenance) of gasoline machines. And this is really an indisputable and proven fact. But on the other hand, if you take the total costs, the cost of ownership of a diesel car in the aggregate is much less than the same gasoline analogue. Especially on those world car markets, where there is an increased demand for diesel cars. Let us explain our readers, the fact is that in the cost of ownership the car must always be taken into account in the second-hand market and the specific loss of the car's market price and the natural wear of all auto parts during the operation of the vehicle (vehicle). As a rule, diesel cars are lost in price much less (and slower) than the same gasoline analogs. Also, due to the higher durability of the diesel engine parts, these cars have a longer service life, which naturally allows you to spend significantly smaller amounts of cash on.

Thus, it can be said that in the long run (from 5 years and above), holding a diesel engine is more profitable than a car with a gasoline unit. True, here friends need to notice that the cost of diesel automodels is usually significantly higher than gasoline. But, if you are in the future for a long time to own such a diz-car and pass on it 20.000 - 30,000 thousand km per year, then such a overpayment will pay off for you at the expense of the same fuel economy.

6. Diesel cars are safer.

Over the years, the following has been proved that diesel fuel is significantly safer than the same gasoline for several reasons. First, the isolar is less susceptible to rapid and light ignition (fire) compared with gasoline. For example, the most diesel fuel is not ignited as a rule, when exposed to a high heat source.

Secondly, - diesel fuel does not highlight dangerous vapors as the same gasoline. As a result, the probability of ignition of vapor salarkey that can cause a fire fire, in diesel vehicles is significantly lower than in the same gasoline.

All these factors make diesel cars on the roads around the world much safer in contrast to gasoline cars. For example, in cases of accidents.

7. In the exhaust of the diesel car, there is less carbon oxide than in gasoline.

From the very beginning of these turbines, engineers faced a certain problem that was associated with the nutrition of these turbocharger. As a rule, the turbine impeller itself rotates due to the energy obtained from the car exhaust gases. If you compare gasoline and diesel cars with each other, the turbines in diesel engines work much more efficiently, since in a diesel car, the number of exhaust gases on the volume produced is much more than in a gasoline unit. It is for this reason that the turbocharger (s) of a diesel engine gives the maximum power much faster and earlier than gasoline cars. That is, already on low speeds begin to feel the maximum power of the car and its torque.

9. Diesel motors without additional modifications can operate on synthetic fuel.

Another major advantage of diesel engines is the possibility of their work on synthetic fuel without any significant changes in the design of the power unit. The gasoline engines are also essentially working on alternative fuel. But it requires significant changes in the design of the power unit. Otherwise, the gasoline engine operating on alternative fuel simply will quickly fail.

Currently, experiments with biobutanol (fuel), which is greatly suitable in the form of a synthetic biofuel for all gasoline cars. This type of fuel may not be caused by gasoline cars of anyone significant harm without any changes in the engine design.

Very common on passenger cars. Many models have at least one option in the motor gamma. And it is excluding trucks, buses and construction equipment, where they are used everywhere. Further reviewed what diesel, design, principle of operation, features.

Definition

This unit is the functioning of which is based on the self-ignition of sprayed fuel from heating or compression.

Design features

The gasoline engine has the same structural elements as diesel. The functioning scheme is generally similar. The difference consists in the processes of formation of the fuel and air mixture and its combustion. In addition, diesel engines are characterized by more durable details. This is due to a roughly high degree of compression than that of gasoline engines (19-24 against 9-11).

Classification

By the design of the combustion chamber, diesel engines are divided into options with a separate combustion chamber and with direct injection.

In the first case, the combustion chamber is separated from the cylinder and is connected to it with the channel. When compressed into a vortex type of air, the air is spinning, which improves the mixing and self-ignition, which begins there and continues in the main chamber. Diesel engines of this type were previously distributed on passenger cars due to the fact that they have differed by a reduced level of noise and a large revolutions from the options discussed.

In with the immediate injection, the combustion chamber is in the piston, and the fuel is fed into the epipper space. This design was originally used on low-speed Motor Motor. They differed in high noise and vibration and low fuel consumption. Later, with the advent of electronic control and optimization of the combustion process, the designers have achieved stable operation at a range of up to 4500 rpm. In addition, economy increased, noise and level of vibrations decreased. Among measures to reduce stiffness of work - multistage antipsychos. Thanks to this, the engines of this type have received extensive distribution over the past two decades.

According to the principle of functioning, diesel engines are divided into four-stroke and two-stroke, like gasoline motors. Their features are discussed below.

Principle of operation

To understand what diesel is and what its functional features are due, it is necessary to consider the principle of operation. The above classification of piston DVS is based on the number of tacts included in the working cycle, which are isolated by the magnitude of the angle of rotation of the crankshaft.

Therefore, includes 4 phases.

Inlet. It occurs when the crankshaft is rotated from 0 to 180 °. In this case, the air passes into the cylinder through an intake valve open at 345-355 °. Simultaneously with it, during the rotation of the crankshaft by 10-15 °, the exhaust valve is open, which is called overlapping.
Compression. Piston, moving up at 180-360 °, compresses air at 16-25 times (compression ratio), and the intake valve closes at the beginning of the clock (at 190-210 °).
Working, expansion. Occurs at 360-540 °. At the beginning of the clock to reach the piston of the upper ground, the fuel is served in hot air and flammified. This feature of diesel engines, distinguishing them from gasoline, where the ignition is ahead occurs. The combustion products distinguishes with the piston down. At the same time, the combustion time of the fuel is equal to the time of its supply to the nozzle and lasts no longer the duration of the working stroke. That is, with the workflow, the pressure of gases constantly, as a result of which diesel engines develop a greater torque. Also an important feature of such motors is the need to ensure an excess of air in the cylinder, since the flame occupies a small part of the combustion chamber. That is, the proportion of the fuel and air mixture is different.
Release. At 540-720 ° crankshaft rotation Open exhaust valve piston, moving up, displaces exhaust gases.

The two-stroke cycle is distinguished by shortened phases and a single gas exchange process in a cylinder (purge) occurring between the end of the working stroke and the beginning of compression. When the piston moves down, the combustion products are removed through the outlet valves or windows (in the cylinder wall). Later, the inlet windows open for the receipt of fresh air. When the piston rises, all windows are closed, and compression begins. A little earlier, the achievements of the NTC are injected and felted fuel, the expansion begins.

Due to the complexity of ensuring the blowing of the vortex chamber, the two-stroke engines are only with immediate injection.

The performance of such engines is higher than 1.6-1.7 times than the characteristics of the four-stroke diesel engine. Its increase is provided by twice by more frequent exercise of work moves, but is partially reduced due to their smaller size and purge. Due to the double number of working moves, the two-stroke cycle is particularly relevant in case of the impossibility of increasing the frequency of rotation.

The main problem of such engines is purging due to its short, which is impossible to compensate for without reducing efficiency due to the shortening of the working stroke. In addition, it is impossible to divide the exhaust and fresh air, which is why the part of the latter is removed with the spent gases. This problem can be solved by ensuring the advance of final windows. In this case, the gases begin to be removed before the purge, and after closing the release, the cylinder is complemented by fresh air.

In addition, when using one cylinder, difficulties arise with the synchronicity of opening / closing windows, therefore there are engines (PDP), in which each cylinder has two pistons moving in the same plane. One of them controls the inlet, the other is the release.

By the implementation mechanism, the purge is divided into slit (window) and valve-slot. In the first case, the windows serve both intake and outlet holes. The second option involves their use as inlets, and for the release serves valve in the cylinder head.

Usually, two-stroke diesel engines are used on heavy vehicles like ships, diesel locomotives, tanks.

Fuel system

Fuel apparatus of diesel engines is much more complicated than gasoline. This is due to high demands for the accuracy of supplying fuel in time, quantity and pressure. The main components of the fuel system - TNVD, nozzles, filter.

Computer control fuel supply system (Common-Rail) is widely applied. She injected him with two portions. The first one is small, serving to increase the temperature in the combustion chamber (antipheracy), which reduces the noise and vibration. In addition, this system increases a 25% torque on small revolutions, reduces fuel consumption by 20% and the content of soot in exhaust gases.

Turbochards.

Turbines are very widely used on diesel engines. This is due to higher (1.5-2) times the pressure of exhaust gases, which are promoting the turbine, which avoids the turboyama, ensuring reducing lower revolutions.

Cold launch

You can find a lot of reviews that, under negative temperatures, the complexity of the launch of such motors in cold conditions is due to the fact that it takes more energy. To facilitate the process, they are equipped with an preheater. This device is represented by incandescent candles placed in combustion chambers, which, when turning on the ignition, heat the air into them and work for another 15-25 seconds after launch to ensure the stability of the immense motor. Due to this, diesel engines at temperatures -30 ...- 25 ° C.

Service features

To ensure durability during operation, you need to know what diesel is and how to serve it. The relatively low prevalence of the motors under consideration in comparison with gasoline is explained as a more complex maintenance.

First of all, it concerns the fuel system of high complexity. Because of this, diesel engines are extremely sensitive to content in fuel and mechanical particles, and its repair is more expensive, as well as the engine as a whole compared to the gasoline level.

If the turbine is also highly high quality engine oil quality requirements. Its resource is usually 150 thousand km, and the cost is high.

In any case, on diesel engines to change the oil more often than on gasoline (2 times on European standards).

As noted, these motors meet the cold launch problems, when at low temperatures in some cases it is caused by the use of unsuitable fuel (depending on the season on such engines, various varieties are used, since the summer fuel is used at low temperatures).

Performance

In addition, many do not like these qualities of diesel engines as smaller power and operating speed, a higher noise level and vibrations.

The gasoline engine is really usually superior in productivity, including liter power, similar diesel. Motor of the type under consideration has a higher and smooth graph of torque. Increased compression ratio, providing greater torque, forces the use of more durable parts. Since they are heavier, the power is reduced. In addition, it affects the mass of the engine, and therefore the car.

A small range of working revolutions is explained by a longer fuel ignition, as a result of which it does not have time to burn on high revs.

The increased level of noise and vibration causes a sharp increase in the pressure in the cylinder when inflammatory.

The main advantages of diesel engines consider higher trapping, efficiency and environmental friendliness.

Taplessness, that is, a high torque on small revolutions is due to the combustion of fuel as an injection. It provides greater responsiveness and facilitates efficient power use.

The cost-effectiveness is due both to the low consumption and the fact that the diesel fuel is cheaper. In addition, it is possible to use low-grade heavy oils as it due to the absence of strict evaporation requirements. And the fuel is harder, the higher the efficiency of the motor. Finally, diesel engines work on poor mixtures in comparison with gasoline engines and with high compression. The latter provides smaller heat losses with exhaust gases, that is, great efficiency. All these measures reduce fuel consumption. Diesel, thanks to this, spends it 30-40% less.

The environmental friendliness of diesel engines is explained by the fact that in their exhaust gases below the content of carbon monoxide. This is achieved by the use of complex cleaning systems, so that now the gasoline engine corresponds to the same environmental standards as diesel. The motor of this type has previously significantly inferior to gasoline in this respect.

Application

As it is clear from what kind of diesel and what is its characteristics, such motors are most suitable for those cases when high traction is needed on low revs. Therefore, they equip almost all buses, trucks and construction techniques. As for private vehicles, among them such parameters are most important for SUVs. Due to the high efficiency, urban models are equipped with these motors. In addition, they are more convenient in management in such conditions. Diesel test drives testify to this.

Some differs from gasoline analogues. The main difference can be considered the ignition of the fuel and air mixture, which is not not from the external source (sparklers), but from strong compression and heating.

In other words, in the diesel engine there is a self-ignition of fuel. In this case, the fuel should be supplied under extremely high pressure, as it is necessary to quickly spray fuel in the diesel engine cylinders. In this article we will talk about which injection systems for diesel engines today are actively used, as well as consider their device and the principle of operation.

Read in this article

How does the diesel engine fuel system

As mentioned above, in the diesel engine there is a self-ignition of the working mixture of fuel and air. At the same time, only air is supplied to the cylinder, then this air is strongly compressed and heated from compression. To marvel, you need to get closer to the end of the compression tact.

Taking into account the fact that the air is strongly compressed, fuel should also be injected under high pressure and spray effectively. In various diesel, the injection pressure may differ, starting on average, from the mark at 100 atmospheres and ending with an impressive indicator of more than 2 thousand atmospheres.

For the most effective fuel supply and providing optimal conditions for the self-ignition charge, followed by a full combustion of the mixture, fuel injection is implemented through a diesel nozzle.

It turns out, regardless of which type of power system is used, two main elements are always present in diesel engines:

device for creating high fuel pressure;

In other words, on many diesel engines, the pressure creates (high pressure fuel pump), and the feeding of diesel fuel in the cylinders occurs through the nozzles. As for the differences, in different systems of fuel feed pumps can have one or another design, and diesel nozzles themselves differ in its device.

Another nutrition systems may differ in the location of certain components, have different control schemes, etc. Let's look at the diesel engines injection systems in more detail.

Diesel Engine Power Systems: Overview

If you divide the nutrition systems of diesel engines that got the greatest distribution, the following solutions can be distinguished:

The power system, which is based on an internal type TNVD (inline TNVD);
The fuel feed system, which has a distribution type TNVD;
Solutions with pump-nozzles;
Common Rail fuel injection (high-pressure battery in total highway).

These systems also have a large number of subspecies, while in each case one or another type is the main one.

So, let's start with the simplest scheme itself, which involves the presence of a row fuel pump. An inline TNVD is a long-known and proven solution that is used on diesel engines for more than a dozen years. Such a pump is actively used on the special equipment, trucks, buses, etc. If you compare it with other systems, the pump is large enough by its dimensions and weight.

In a nutshell, the basis of the row TNVD lie. Their number is equal to the number of engine cylinders. The plunger pair is a cylinder that moves in the "glass" (sleese). When moving up, a fuel compression occurs. Then, when the pressure reaches the desired indicator, the special valve is opening.

As a result, pre-compressed fuel enters the nozzle, after which the injection occurs. After the plunger starts to move back down, a channel for inlet of fuel opens. Through the channel fuel fills the space over the plunger, then the cycle is repeated. So that the diesel fuel fell into the plunger pairs, additionally in the system there is a separate pumping pump.

Plungers themselves work due to the fact that the pumping shaft is available in the pump device. This shaft works like, where the cams are "pushing" the valve. The pump shaft itself is driven from the engine, since the TNVD is connected to the engine using the injection advance coupling. The specified coupling allows you to adjust the work and adjust the TNVD during the operation of the engine.

The power supply system with the distribution pump is not very different from the circuit with row TNLD. The distribution pump is similar to in line according to the design, while it reduces the number of plunger pairs.

In other words, if the pair in the row pump is necessary for each cylinder, then 1 or 2 plunger pairs are enough in the distribution. The fact is that one pair in this case is enough to supply fuel in 2, 3 or even 6 cylinders.

This became possible due to the fact that the plunger got the opportunity not only to move up (compression) and down (inlet), but also rotate around the axis. Such rotation made it possible to realize the alternate opening of the outlet holes through which the diesel fuel under high pressure is fed to the nozzles.

Further development of this scheme led to the emergence of a more modern rotary TNVD. In such a pump, a rotor is applied in which plungers are installed. These plungers move towards each other, and the rotor rotates. This is how compression and distribution of diesel fuel pumps through the motor cylinders.

The main advantage of the distribution pump and its varieties is reduced weight and compactness. At the same time to customize this device more difficult. For this reason, electronic control and adjustment schemes are additionally used.

The pump-nozzle type power system is a scheme where a separate pump is originally absent. If more precisely, the nozzle and the pumping section were combined in one case. There is already a familiar plunger pair.

The solution has a number of advantages in comparison with systems in which the TNVD is used. First of all, you can easily adjust the fuel supply to individual cylinders. Also in the event of a single nozzle failure, the rest will work.

Also using pump-nozzles allows you to get rid of a separate TNVD drive. Plungers in the pump pump are driven by the timing camshaft, which is installed in. Such features allowed diesel engines with pump-nozzles to get widespread not only on trucks, but also on large passenger cars (for example, diesel SUVs).

The Common Rail system is one of the most modern solutions in the field of fuel injection. Also, this power circuit allows you to achieve maximum efficiency simultaneously with high. In parallel, the toxicity of exhaust gases is reduced.

The system was developed by the German company Bosch in the 90s. Taking into account the obvious advantages in a short time, the overwhelming majority of diesel engines on passenger and cargo cars began to equip exclusively Common Rail.

The overall scheme of the device is based on the so-called high pressure battery. If simply, fuel is under constant pressure, after which it is fed to the nozzles. As for the pressure accumulator, this battery is actually a fuel lead, where fuel is injected using a separate TNVD.

The Common Rail system partially resembles a gasoline injection engine that has fuel ramp with nozzles. Gasoline in the ramp (fuel rail) is injected under low pressure by gas station from the tank. In the diesel, the pressure is much higher, the fuel is injected by TNVD.

Due to the fact that the pressure in the battery constant, it became possible to implement the fast and "multilayer" fuel injection through the nozzles. Modern systems in Common Rail engines allow nozzles to make up to 9 dosage injections.

As a result, the diesel engine with such a system is economical, productive, works softly, quiet and elastic. Also, the use of a pressure battery made it possible to make the design of the TNVD on diesel motors simpler.

We add that the high-precision injection on the Common Rail engines is completely electronic, as a separate control unit monitors the system. The system uses a group of sensors that allow the controller to accurately determine how many diesel fuel should be submitted to the cylinders and at what point.

Let's summarize

As can be seen, each of the considered diesel engine power systems has its advantages and disadvantages. If we talk about the simplest solutions with row TNVD, their main plus can be considered the possibility of repair and availability of service.

In diagrams with pump-nozzles, you need to remember that these elements are sensitive to the quality of fuel and its purity. Increasing even the smallest particles may fail the pump-nozzle, as a result of which the expensive element will require replacement.

As for the Common Rail systems, the main disadvantage is not only the high initial cost of such solutions, but also the complexity and high cost of subsequent repair and maintenance. For this reason, the quality of fuel and the state of fuel filters must be constantly monitored, and also timely hold scheduled maintenance.

How does diesel engine work?

It is the principle of operation of a diesel engine in the following: in the cylinder

clear air is absorbed when the piston moves down. And when moving the valve up it heats up. It is worth noting that the temperature during the operation of the diesel engine can be from 700 to 900 °. This is achieved with strong compression. When the piston moves into a dead top point, the diesel fuel is injected into the combustion chamber under sufficiently high pressure. When contacting with hot air, fuel is inflated. As a result, the pressure in the cylinder increases, since self-represented fuel expands. This is exactly what causes strong noise when working as an aggregate.

Advantages and disadvantages

This principle of operation of the diesel engine allows the use of a poor mixture. Fuel for such devices relatively inexpensive. This makes diesel motors unpretentious and economical. It is worth noting that in contrast to gasoline such aggregates have a large torque, and the efficiency is 10% higher than. To minuses

the diesel engine should include an elevated noise level, vibration, low power per unit volume, the complexity of the cold start. More modern models are practically deprived of such flaws.

Device and features of some nodes

Given the principle of operation of the diesel engine, the details to such aggregates are significantly enhanced, as they must withstand high loads. Among the main parts of the unit it is worth highlighting the piston. The shape of his bottom depends on the type of combustion chamber, which can be built into the bottom of the valve. In the piston for a diesel engine, the bottom is usually over the top of the cylinder block. The usual ignition system in the aggregates of this type is not. Although they also apply candles.

Turbine

The power capable of developing the motor depends on the amount of fuel and air that come to it. To increase the capabilities of the unit, it is necessary to increase the content of the listed components. For admission to the combustion chamber of more fuel, the air level should be raised, which

enters the cylinder. For this, additional equipment is applied. The principle of operation of the turbine of the diesel engine is quite simple. Detail allows you to pump more air. Due to this, the volume of combustion fuel increases, which significantly increases the amount of energy allocated.

Cameras combustion

In diesel engines, the combustion chambers of several types can be used: separated and undivided. The first type was used in passenger engineering, but recently replaced it on a simpler. Indeed, when using separated compartments, the fuel was injected into that combustion chamber, which was located in the cylinder head, and not in the piston cavity. These parts were performed in different ways and it was dependent on the processes of the mixture of the mixture: the dramatic -merous or pre-commercial.

In the latter case, the fuel is injected into the preliminary compartment, which

it is reported to small valves or cylinder holes. At the same time, fuel mixed with air, hitting the wall. Self-represented fuel enters the main chamber, where it is completely burning. As for the dramaticimenal combustion process, it, as in the first case, begins in a separate compartment, which is a hollow sphere. Through the connecting channels, the air falls during the compression tact in the chamber. Twisted in it and forms a whirlwind. As a result, the combustible mixture, injected into the compartment, is well mixed with air. This structure of combustion chambers has several drawbacks. First, more fuel is spent, as large losses occur due to the volume of compartments. Secondly, significant losses when flowing into an additional chamber from the air cylinder, as well as to the reverse process: moving fuel to the cylinder. It should be noted that such a principle of operation of the diesel engine is rarely used, since there is a deterioration in the starting characteristics of the unit.

Untreated combustion chambers

In the engine with the immediate injection, combustion compartment has a certain form and is a cavity. Embeds such a combustion chamber directly in the bottom

piston. In this case, the fuel is injected immediately into the cylinder. Despite the simplicity of the design, there are also disadvantages in such a system. Diesel motors of such a plan are almost impossible to use if the car has small litters. When the speed set in such a vehicle, there is an increase in noise level, and vibration increases.

New Developments

Today, electronic systems are used more often, which control the amount of fuel combustion entered into the chamber. This made it possible to reduce the noise level, as well as the vibration of the unit during operation. Today, completely new diesel engines are being developed, in the structures of which the immediate injection of the combustible mixture is used.

According to the prevailing ideas, diesel engines produce a lot of noise, it is unpleasant to smell and do not give the necessary power. It is believed that they are only suitable for trucks, vans and a taxi. Perhaps in the 1980s. Everything was so, but since then the situation has changed in the root. Diesel engines and fuel injection systems are much more perfect. In 1985 In the UK, almost 65,000 cars with diesel engines were sold (approximately 3.5% of the total car sold). For comparison, in 1985 Total 5380 was sold. (Data is probably for the US market).

The main parts of the diesel engine must be stronger than the engine running on gasoline.

Ignition.For ignition, sparks are not required, because The mixture is flammable under the action of compression.

Funny candles. Heat the combustion chamber at a cold start.

Many diesel engines were created on the basis of gasoline engines, but their main parts have increased strength and are able to withstand high pressure.

Fuel enters the engine due to the discharge pump with a dispenser, which is usually attached to the side of the cylinder block. The system does not use electrical ignition.

The main advantage of diesel engines before gasoline is to reduce operating costs. Diesel engines have greater efficacy due to strong compression and low fuel cost. Of course, the prices for diesel can vary, so the car with a diesel engine will cost you expensive if you live in the region with high prices for diesel fuel. In addition, such cars are less likely to maintain, but the oil replacement for them is organized more often than for cars that work on gasoline.

Increase power

The main disadvantage of diesel engines is their low power compared to gasoline engines of equal volume.

This problem can be solved by simply increasing the engine volume, but often it leads to a significant weight gain of the car.

Some manufacturers provide their engines to turbocharger to increase their competitiveness. For example, the production of turbo diesel engines are engaged in Rover, Mercedes, Audi and VW.

How do diesel engines work

Inlet

When the piston moves down the cylinder opens the intake valve, encompassing the air.

Compression

When the piston reaches the lower base of the cylinder, the intake valve closes. Piston rises, squeezing air.

Ignition

The fuel is injected into the cylinder when the piston comes to top base. In this case, the fuel flashes and again leads the piston in motion.

Release

On the way back, the piston opens the release valve, and the spent gas comes out of the cylinder.

Four-stroke diesel and gasoline engines work in different ways, despite the fact that they include the same components. The main difference lies in the method of igniting fuel and control of the resulting energy.

In the engine running on gasoline, a mixture of air and fuel is lit from the spark. In the diesel engine, fuel flashes under the action of compressed air. In diesel engines, the air is compressed on average in a 1/20 ratio, at that time for gasoline engines - this ratio is average equal to 1/9. Such compression greatly heats the air to a temperature sufficient for instant fuel ignition, so when using a diesel engine there is no need for sparking or other ignition methods.

Gasoline engines absorb a lot of air for one piston clock (the specific volume depends on the degree of opening of the throttle opening). Diesel engines always absorb the same volume that depends on the speed, while the air core is not equipped with a throttle. It overlaps one inlet valve, and in the engine there is no carburetor and disk shutter.

When the piston reaches the bottom base of the cylinder, the inlet valve opens. Under the action of energy from other pistons and pulse from the flywheel, the piston is sent to the upper base of the cylinder, squeezing the air about twenty times.

As soon as the piston reaches the top base, a carefully measured amount of diesel fuel is injected into the combustion chamber. The air heated during compression instantly flammives fuel, which expands when combustion and again sends the piston down, turning the crankshaft.

When the piston moves up the cylinder on the output tact, the exhaust valve opens, allowing the exhaust and expansioned gases to exit the exhaust pipe. At the end of the release tact, the cylinder is ready for a new portion of fresh air again.

Diesel engine design

The diesel and gasoline engine consist of the same parts that perform the same functions. However, parts of the diesel engine have increased strength, because They are designed to withstand a larger load.

The walls of the diesel engine unit are usually much thicker than the walls of the gasoline engine. They are reinforced with additional lattices that block pulses. In addition, the unit of the diesel engine effectively absorbs noise.

Pistons, connecting rods, shafts and lids of bearings housing are made of the most durable materials. The cylinder head of the diesel engine has a special form associated with the shape of the nozzles, as well as forms of combustion chamber and the drainage.

Injection

For smooth and efficient operation of any internal combustion engine, the correct mixture of air and fuel is required. For diesel engines, this problem is especially relevant, because Air and fuel are served at different times, mixing inside the cylinders.

Fuel injection into the engine can be straight and indirect. According to the current tradition, the indirect injection is often used, because It allows you to create vortex streams that mix fuel and compressed air in the combustion chamber.

Direct injection

With a direct injection, fuel falls directly into the combustion chamber located in the piston head. Such a shape of the chamber does not allow you to mix air with fuel and adjust the resulting mixture without a rigid knock characteristic of diesel engines.

In the engine with indirect injection, a small spiral joint is usually present (forcamera). Before hitting the combustion chamber, the fuel passes through the vortex meter, and it forms a vortex streams that provide better mixing with air.

The disadvantage of this approach is that the vortexer becomes part of the combustion chamber, which means that the whole design acquires an improper form, causes problems during combustion and negatively affects the efficiency of the engine.

Indirect injection

With indirect injection, fuel falls into a small fork meter, and from there to the combustion chamber. As a result, the design acquires an incorrect form.

The engine with direct injection is not equipped with a whirlpool, and the fuel is straightforward into the combustion chamber. When designing combustion chambers in the head of the piston, engineers should pay special attention to their shape to ensure adequate vortices.

Outside candles

To warm up the cylinder head and the cylinder block in front of a cold start, in diesel engines are used with ignition candles. Short and wide candles are an integral part of the car electrical system. When you turn on the power, elements in the candles are very quickly heated.

The wicked candles are turned on with a special turn of the steering column or using a separate switcher. In the latest models, the candles are turned off automatically, as soon as the engine is heated and accelerates to a speed greater than the idle speed.

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Unlike gasoline engines, in diesel engines there is no choke, so the amount of air consumed remains unchanged. The engine rotation frequency is determined only by the volume of fuel injected into the combustion chamber. The more fuel, the more energy is allocated during combustion.

The gas pedal is connected to the sensor in the ignition system, and not to the throtsel, as in cars that work on gasoline.

To stop the diesel engine, you still need to rotate the ignition key. In this gasoline engine, the spark disappears, and in diesel - the solenoid is turned off, which is responsible for supplying fuel into the pump. After that, the engine spends the fuel remaining in it and stops. In fact, diesel engines stop faster than gasoline, because high pressure slows down the move.

How to start a diesel engine

Diesel engines, like gasoline, are hardened when the electric motor that runs the compression and ignition cycle is turned on. However, at low temperatures, diesel engines are struggling with difficulty, because the compressed air is not heated to the temperature necessary for fuel ignition.

To solve this problem, manufacturers make outstanding candles. Outside candles are electrothera fed from the battery, which are included in a few seconds before starting the engine.

Diesel fuel

The fuel used in diesel engines is very different from gasoline. It does not undergo clean, and therefore is a viscous heavy liquid that evaporates quite slowly. Thanks to these physical properties, diesel fuel is sometimes called diesel oil or fuel oil. In service centers and at refueling cars operating on diesel fuel are often called wood (from Diesel-Engined Road vehicles).

In cold weather, diesel fuel is quickly thick or even freezes. In addition, it contains a small amount of water, which can also freeze. All types of fuel are absorbed from the atmosphere of water. Moreover, it often penetrates underground tanks. The permissible water content in diesel fuel is 0.00005-0.00006%, i.e. A quarter of a glass of water for 40 liters of fuel.

Ice or water cork can block fueling and nozzles, which makes it impossible to work the engine. That is why in cold weather you can see drivers who are trying to heat the fuel line with a soldering iron.

As a preventive measure, you can carry with an additional tank with you, however, modern producers are already added to the fuel of impurities that allow it to be used at temperatures above -12-15 ° C.