The same year he was successfully tested. Diesel actively engaged in selling licenses for a new engine. Despite the high efficiency and ease of operation compared to the steam engine, the practical application of such an engine was limited: he inferior to steam machines of the time in size and weight.

The first diesel engines worked on vegetable oils or lung petroleum products. Interestingly, it was originally as an ideal fuel offered coal dust. Experiments showed the impossibility of using coal dust as fuel - primarily due to the high abrasive properties of both the dust itself and ash, obtained during combustion; Also there were large problems with dust in cylinders.

Principle of operation

Four-stroke cycle

• 1st tact. Inlet. Corresponds to 0 ° - 180 ° rotation of the crankshaft. Through open ~ from 345-355 °, the air intake valve enters the cylinder, on 190-210 ° valve closes. At least up to 10-15 ° crankshaft rotation at the same time, the exhaust valve is open, the joint opening time of the valves is called overlapping valve .
• 2nd tact. Compression. Corresponds to 180 ° - 360 ° rotation of the crankshaft. The piston, moving to the VTT (upper dead point), compresses the air to 16 (in low-speed) -25 (in the speed) times.
• 3rd tact. Working, expansion. Corresponds to 360 ° - 540 ° rotation of the crankshaft. When spraying fuel in hot air, the fuel combustion is initiated, that is, its partial evaporation, the formation of free radicals in surface layers of droplets and in paráh, finally, it flashes and burns as far as the injectors arrived, burning products, expanding, move the piston down. Injection and, accordingly, fuel ignition occurs a little earlier than the moment of reaching the piston of the dead point due to some inertness of the combustion process. The difference from the ignition advance in gasoline engines is that the delay is necessary only due to the presence of initiation time, which in each specific diesel - is not subject to permanent and change during operation. The combustion of fuel in the dieselle occurs, thus, for a long time, so much time, how long is the flow of portion of fuel from the nozzle. As a result, the workflow proceeds with a relatively constant pressure of gases, which is why the engine develops a large torque. Two major output are followed from this.
  • 1. The combustion process in the dieselle lasts exactly so much time as required for the injection of this portion of fuel, but no longer the time of the working stroke.
  • 2. The ratio of fuel / air in a diesel cylinder can differ significantly from stoichiometric, and it is very important to ensure an excess of air, since the flame of the torch occupies a small part of the combustion chamber volume and the atmosphere in the chamber must prior to the latter to ensure the desired oxygen content. If this does not occur, there is a massive release of unburned hydrocarbons with soot - "Temloom" gives a "bear".).
• 4th tact. Release. Corresponds to 540 ° - 720 ° crankshaft rotation. The piston goes up, through open at 520-530 ° exhaust valve piston pushes the spent gases from the cylinder.

Depending on the combustion chamber design, there are several types of diesel engines:

• Diesel with an undivided camera: The combustion chamber is made in the piston, and the fuel is injected into the epipper space. The main advantage is the minimum fuel consumption. The disadvantage is an increased noise ("tough work"), especially at idle. Currently, intensive work is underway to eliminate the specified shortage. For example, in the COMMON Rail system to reduce the stiffness of the work (often multistage) antipsychos.
• Diesel with a separated chamber: Fuel is served in an additional chamber. In most diesel engines, such a chamber (it is called a vortex or pre-tariff) is associated with a cylinder with a special channel so that when compressing the air, falling into the camera, it swollen intensively. This contributes to a good mixing of the injected fuel with air and more complete fuel combustion. Such a diagram was considered optimal for light diesel engines and was widely used on passenger cars. However, due to the worst economy, the last two decades there is an active displacement of such diesel engines with an inseparable chamber and with Common Rail fuel systems.

Two-stroke cycle

Purpose of the two-stroke diesel engine: down - purge windows, the exhaust valve is asleep open

In addition to the above-described four-stroke cycle, in diesel, it is possible to use a two-stroke cycle.

At the working trip, the piston goes down, opening the outlet windows in the cylinder wall, the exhaust gases overlook, at the same time open windows open, the cylinder is blown out with fresh air from the blower - purge combining intake and release tacts. When the piston rises, all windows are closed. From the moment of closing the intake windows, compression begins. A little without reaching the NTT, the fuel is sprayed from the nozzle and lights up. Expansion occurs - the piston goes down and again opens all the windows, etc.

Blowing is a congenital weak point of the two-stroke cycle. The purge time, in comparison with other clocks, it is impossible, it is impossible to increase it, otherwise the efficiency of the working move will fall due to its shortening. In the four-stroke cycle, half of the cycle is given to the same processes. Fully split exhaust and fresh air charge is also impossible, so the air is lost, leaving right into the exhaust pipe. If the shift of the clock provides the same piston, the problem arises associated with the symmetry of opening and closing windows. For better gas exchange it is more profitable to have ahead of the opening and closing of exhaust windows. Then the exhaust, starting earlier, will reduce the pressure of residual gases in the cylinder to the beginning of the purge. With the previously closed exhaust windows and open - still - inlets are carried out with a coil of the cylinder with air, and if the blower provides overpressure, it becomes possible to carry out superior.

Windows can be used for exhaust exhaust gases, and for intake fresh air; This purge is called slit or window. If the spent gases are produced through the valve in the cylinder head, and the windows are used only for intake fresh air, purging is called valve-slot. There are engines where in each cylinder there are two meet-moving pistons; Each piston manages its windows - one intake, other graduation (Ferbenx-Morse system - Junkers - Korevo: Diesels of this system of the D100 family were used on TE3 diesel locomotives, TE10, tank engines 4TPD, 5TD (f) (T-64), 6TD (t -80ud), 6TD-2 (T-84), in aviation - on Junkers bombers (Jumo 204, Jumo 205).

In the two-stroke engine, working turns occur twice as much as in the four-stroke, but due to the presence of purging the two-stroke diesel is more powerful than 1.6-1.7 times in the amount of a four-stroke maximum.

Currently, low-speed two-stroke diesel engines are very widely used on large maritime ships with direct (unprecedented) drive propeller. Due to the doubling of the number of work moves on the same turns, the two-stroke cycle is advantageous if it is impossible to increase the frequency of rotation, in addition, the two-stroke diesel is technically easier to reverse; Such low-speed diesel engines have a capacity of up to 100,000 hp.

Due to the fact that it is difficult to organize the purge of the vortex chamber (or pre-stop) at a two-stroke cycle, the two-stroke diesel engines are built only with undivided combustion chambers.

Design options

For medium and heavy two-stroke diesel engines, the use of composite pistons is characterized in which the steel head and duralum skirt is used. The main purpose of this complication of the design is to reduce the total weight of the piston while maintaining the maximum possible heat resistance of the bottom. Very often used constructions with oil liquid cooling.

Four-stroke engines are allocated to a separate group containing Creicopf in the design. In Creicopful engines, the connecting rod joins the Creiccopfu - the slider connected to the piston rod (rolling pin). Creicopf works in his guide - the crown, without the effects of elevated temperatures, completely eliminating the impact of lateral forces on the piston. This design is characteristic of large long-time ship engines, often double action, the piston move in them can reach 3 meters; Thrinking pistons of such sizes would be overheated, tries with such a friction area would significantly reduce the mechanical efficiency of the diesel engine.

Reversible engines

The combustion of the fuel injected into the cylinder is occurs as an injection. Therefore, diesel gives a high torque at low revs, which makes a car with a diesel engine more "responsive" in motion than the same car with a gasoline engine. For this reason, and due to higher efficiency, most trucks are currently equipped with diesel engines . For example, in Russia in 2007, almost all trucks and buses were equipped with diesel engines (the final transition of this segment of vehicles from gasoline engines to diesel engines was planned to be completed by 2009). This is also an advantage in the engines of sea vessels, since the high torque at low revs makes more easy to efficiently use the engine power, and a higher theoretical efficiency (see Carno cycle) gives higher fuel efficiency.

Compared to gasoline engines, in the exhaust gases of the diesel engine, as a rule, less carbon monoxide (CO), but now, in connection with the use of catalytic converters on gasoline engines, this advantage is not so noticeable. The main toxic gases that are present in the exhaust in noticeable quantities are hydrocarbons (ns or CH), nitrogen oxides (NO) and soot (or derivatives) in the form of black smoke. Most polluted the atmosphere in Russia Diesels of trucks and buses, which are often old and non-regulated.

Another important aspect of security is that diesel fuel is non-volatile (that is, it does not easily evaporate) and, thus, the probability of fire in diesel engines is much smaller, especially since the ignition system is not used. Together with high fuel efficiency, this was the reason for the wide use of diesel engines on tanks, since the risk of fire in the engine compartment was decreased in everyday neborement exploration due to fuel leaks. The smaller fire hazard of the diesel engine in combat conditions is a myth, since when armor breaks, the projectile or its fragments have a temperature that highly exceeds the flash of the vapor of diesel fuel and is also able to simply set fire to the resulting fuel. The detonation of a mixture of vapors of diesel fuel with air in a fuel tank through its consequences is comparable to the explosion of ammunition, in particular, in T-34 tanks, it led to the rupture of welds and knock out the top front desk of the armorpus. On the other hand, a diesel engine in a tank building is inferior to the carburetor in terms of specific power, and therefore in some cases (high power with a small volume of the engine compartment) more advantageous can be the use of precisely carburetor power unit (although it is typical for too light combat units).

Of course, there are disadvantages, among which is a characteristic knock of a diesel engine at its work. However, they are noted mainly by car owners with diesel engines, and for a third-party person almost invisible.

The obvious disadvantages of diesel engines are the need to use a high-power starter, clouding and frosting (sprinkling) of summer diesel fuel at low temperatures, complexity and higher price in the repair of fuel equipment, since high pressure pumps are precision devices. Also, diesel motors are extremely sensitive to fuel contamination with mechanical particles and water. Repair of diesel engines is usually significantly more expensive than the repair of gasoline engines of a similar class. The liter power of diesel engines also, as a rule, is inferior to similar indicators of gasoline engines, although diesel engines have a faster and high torque in their working volume. Environmental indicators of diesel engines significantly inferior to recently gasoline engines. On classical diesel engines with a mechanically controlled injection, only oxidative neutralizers of exhaust gases operating at a temperature of exhaust gas over 300 ° C are possible, which oxidize only CO and CH to harmful carbon dioxide (CO 2) and water. Also earlier, these neutralizers were out of order due to poisoning by their sulfur compounds (the number of sulfur compounds in the exhaust gases directly depends on the amount of sulfur in diesel fuel) and deposits on the surface of the catalyst of soot particles. The situation began to change only in recent years due to the introduction of the diesel engines of the so-called Common Rail system. In this type of diesel engines, the fuel injection is carried out by electronically controlled nozzles. The control of the control electrical pulse performs an electronic control unit receiving signals from the sensor set. The sensors also track different engine parameters affecting the duration and moment of supplying the fuel pulse. So, the complexity is modern - and environmentally friendly, as well as a gasoline-diesel engine is nothing inferior to its gasoline fellow, but for a number of parameters (complexity) and significantly exceeds it. For example, if the pressure of the fuel in the nozzles of a conventional diesel engine with a mechanical injection ranges from 100 to 400 bar (approximately equivalent to "atmospheres"), then in the newest systems "Common-Rail" it is in the range from 1000 to 2500 bar, which goes for It is considerable problems. Also, the catalytic system of modern transport diesel engines is much more complicated than gasoline engines, since the catalyst must "be able to" operate under the conditions of an unstable composition of exhaust gases, and in paragraph cases, the introduction of the so-called "particulate filter" (DPF is a solid particle filter). The "Syft Filter" is a similar to the usual catalytic neutralizer the structure installed between the exhaust collector of a diesel engine and the catalyst in the exhaust flow. The particulate filter develops a high temperature in which the soot particles are capable of oxidizing residual oxygen contained in exhaust gases. However, part of the soot is not always oxidized, and remains in the "scenic filter", so the control unit program periodically translates the engine into the "cleaning filter cleaning" mode by the so-called "posting", that is, the injection of the additional amount of fuel in the cylinders at the end of the combustion phase with the aim of Raise the temperature of the gases, and, accordingly, clean the filter by burning the accumulated soot. The standard of de facto in the designs of transport diesel engines was the presence of a turbocharger, and in recent years - and "intercooler" - devices, cooling air after compression turbocharger - to get a big one after cooling mass air (oxygen) in the combustion chamber with the former bandwidth of the collectors, and The supercharger made it possible to lift the specific power characteristics of mass diesel engines, as it allows you to skip a larger amount of air through cylinders.

For its basis, the design of the diesel engine is similar to the design of the gasoline engine. However, similar parts in a diesel engine are harder and more resistant to high compression pressures, having a place in a diesel engine, in particular, Hon on the surface of the cylinder mirror is more coarse, but the solidity of the walls of the cylinder block is higher. Piston heads, however, are specially designed to combat the combustion in diesel engines and are almost always designed for an increased degree of compression. In addition, the piston heads in the diesel engine are above (for a car diesel engine) of the upper plane of the cylinder block. In some cases, in obsolete diesel engines - piston heads contain a combustion chamber ("direct injection").

Scope of application

Diesel engines are used to drive stationary power plants, on rail (diesel locomotive, dieselosis, diesel trains, autodresions) and firewood (cars, buses, trucks) vehicles, self-propelled machines and mechanisms (tractors, asphalt rollers, scrapers, etc. ), as well as in shipbuilding as the main and auxiliary engines.

Myths about diesel engines

Diesel turbocharged engine

• The diesel engine is too slow.

Modern diesel engines with a turbocharger system are much more efficient than their predecessors, and sometimes exceed their gasoline atmospheric (without turbocharging) fellow with the same volume. This is talking about this Diesel prototype Audi R10, which won the 24-hour race in Le Mans, and new BMW engines that are not inferior at the power of atmospheric (without turbocharging) gasoline and at the same time have a huge torque.

• The diesel engine works too loudly.

Loud engine operation indicates incorrect operation and possible faults. In fact, some old diesel engines with direct injection are really distinguished by a very rigid job. With the advent of the battery fuel systems of high pressure ("Common-Rail") in diesel engines, it was possible to significantly reduce the noise, primarily due to the separation of one injection pulse to several (typically - from 2 to 5 pulses).

• The diesel engine is much more economical.

The main efficiency is due to a higher efficiency of the diesel engine. On average, modern diesel consumes fuel up to 30% less. The life of the diesel engine is greater than gasoline and can reach 400-600 thousand kilometers. Spare parts for diesel engines are somewhat more expensive, the cost of repair is as higher, especially fuel equipment. According to the above reasons, the cost of operation of the diesel engine is somewhat less than that of gasoline. Saving compared with gasoline engines increases in proportion to power, which determines the popularity of the use of diesel engines in commercial transport and heavy vehicles.

• The diesel engine cannot be converted to the use of cheaper gas as fuel.

From the first moments of the construction of diesel engines, a huge number of them, designed to work on gas of various compositions, was built and built. There are mainly two ways to transfer diesel engines for gas. The first method is that the cylinders are served the depleted gas-air mixture, it is compressed and a small rigorous jet of diesel fuel is mounted. The engine operating in this way is called gas dial. The second method consists in converting a diesel engine with a decrease in the degree of compression, the installation of the ignition system and, in fact, with the construction of a gas engine instead of a diesel engine based on it.

Recordsmen

The largest / powerful diesel engine

Configuration - 14 cylinders in a row

Operating volume - 25,480 liters

Cylinder diameter - 960 mm

Piston stroke - 2500 mm

Average efficient pressure - 1.96 MPa (19.2 kgf / cm²)

Power - 108 920 hp at 102 rpm. (return from liter 4.3 hp)

Torque - 7 571 221 N · m

Fuel consumption - 13,724 liters per hour

Dry mass - 2300 tons

Dimensions - Length 27 meters, Height 13 meters

The largest diesel engine for a truck

MTU 20V400. Designed to install for career dump truck BelAZ-7561.

Power - 3807 hp at 1800 rpm. (Specific fuel consumption at rated power 198 g / kW * h)

Torque - 15728 N · m

The largest / powerful serial diesel engine for serial passenger car

Audi 6.0 V12 TDI Since 2008, it is installed on the Audi Q7 car.

Configuration - 12 cylinders V-shaped, the angle of collapse is 60 degrees.

Operating volume - 5934 cm³

Cylinder diameter - 83 mm

Piston stroke - 91.4 mm

Compression ratio - 16

Power - 500 hp at 3750 rpm. (return from the liter - 84.3 hp)

Torque - 1000 nm in the range of 1750-3250 rpm.

The principle of which is based on the self-ignition of fuel when exposed to hot compressed air.

The design of the diesel engine is generally not much different from the gasoline engine, except that the diesel is missing as such a ignition system, since fuel ignition occurs on another principle. Not from spark, as in a gasoline engine, and from high pressure, with which air is compressed, because of which he is heavily warmed up. High pressure in the combustion chamber imposes special requirements for the manufacture of valves parts that are designed to perceive more serious loads (from 20 to 24 units).

Diesel engines are applied not only on freight, but also on many models of passenger cars. Diesels can work on different types of fuel - on rapeseed and palm oil, on fractional substances and clean oil.

Diesel engine action principle

The principle of operation of a diesel engine is based on compression ignition of fuel, which enters the combustion chamber and is mixed with hot air mass. The working process of the diesel engine depends solely on the heterogeneity of the fuel assembly (fuel and air mixture). The supply of TVS in such a type of engine is separated.

Initially, air is supplied, which in the compression process heats up to high temperatures (about 800 degrees Celsius), then fuel is supplied to the combustion chamber under high pressure (10-30 MPa), after which it occurs its self-ignition.

The process of fuel ignition is always accompanied by high levels of vibration and noise, therefore diesel engines are more noisy in comparison with gasoline fellows.

This principle of diesel operation allows you to use more accessible and cheap (until recently :)) Fuel types, reducing the cost level of its maintenance and refueling.

Diesels can have both 2 and 4 work clutches (inlet, compression, work stroke and release). Most cars are equipped with 4-clock diesel engines.

Types of diesel engines

According to the structural features of the combustion chambers, diesel engines can be divided into three types:

• With a separated combustion chamber. In such devices, fuel supply is not carried out in the main, but in an additional, so-called. The vortex chamber, which is located in the head of the cylinder block and is connected to the cylinder of the channel. When entering the vortex chamber, the air mass is maximally compressed, thereby improving the process of fuel ignition. The process of self-ignition begins in the vortex chamber, then goes to the main combustion chamber.
• With an undivided combustion chamber. In such diesel engines, the camera is located in the piston, and fuel is fed into space above the piston. Inseparable combustion chambers on the one hand allow you to save fuel consumption, on the other hand, increase the noise level when the engine is running.
• Pre-commercial motors. Such diesel engines are equipped with a plug-in forkamera, which is connected to the cylinder with thin channels. The shape and size of the channels determine the speed of movement of gases when combustion of fuel, reducing noise and toxicity, increasing the resource of the engine.

Fuel system in diesel engine

The basis of any diesel engine is its fuel system. The main task of the fuel system is the timely supply of the desired amount of fuel mixture under the specified working pressure.

Important elements of the fuel system in the diesel engine are:

• high pressure pump for fuel supply (TNVD);
• fuel filter;
• injectors

Fuel pump

The pump is responsible for supplying fuel to nozzles according to the set parameters (depending on the number of revolutions, the operating position of the regulatory lever and turbocharging pressure). Two types of fuel pumps can be used in modern diesel engines - row (plunger) and distribution.

Fuel filter

The filter is an important part of the diesel engine. The fuel filter is selected strictly according to the type of engine. The filter is designed to highlight and remove water from fuel, and excess air from the fuel system.

Injectors

Nooks no less important elements of the fuel system in the diesel. The timely supply of the fuel mixture into the combustion chamber is possible only when the fuel pump and nozzles interact. Two types of nozzles are used in diesel engines - with a multi-stroke and font distributor. The injector distributor determines the form of a torch, providing a more efficient process of self-ignition.

Cold Start and Diesel Engine Turbochard

Cold Start is responsible for the mechanism of preheating. This is ensured by the electric heating elements - incandescent candles, which are equipped with a combustion chamber. When the incandescent candle engine is started, a temperature of 900 degrees reaches a temperature of 900 degrees, heated air mass, which enters the combustion chamber. Powered from incandescent candles is removed after 15 seconds after the engine is started. Preheating systems Before starting the engine, provide its safe launch even at low atmospheric temperatures.

Turbocaddv is responsible for increasing the power and efficiency of the diesel engine. It provides a larger air supply for a more efficient combustion process of the fuel mixture and increasing engine operating power. To ensure the desired pressurization pressure of the air mixture in all engine operating modes, a special turbocharger is applied.

It remains only to say that disputes regarding what it is better to choose an ordinary motorist as a power plant in his car, gasoline or diesel, do not subside until now. Benefits and disadvantages have both types of engine and it is necessary to choose, based on the specific operating conditions of the car.

It is worth starting with the fact that the efficiency of the diesel engine is much higher than that of a gasoline analogue. Simply put, this motor consumes much less fuel. A similar result designers managed to achieve due to the creation of a unique design.

Important! The principle of operation of the diesel engine is very different from gasoline.

Of course, modern gasoline engines have many diverse technological innovations. It is enough to remember the direct injection. Despite this, the efficiency of the gasoline motor is about 30 percent. Diesel, the same parameter reaches 40. If you recall the turbocharger, then the figure can reach up to 50%.

It is not surprising that diesel motors gradually conquer Europe. Dear gasoline stimulates buyers to buy more economical machines. Real-time manufacturers are monitored in consumer preferences, implementing appropriate adjustments to the production process.

Unfortunately, the design of the diesel engine is not devastable. One of the most significant is a big weight. Of course, the engineers did a huge path, gradually reducing the weight of the motor, but only there is a limit.

The fact is that in the device of a diesel engine, all items must be fitted to each other as accurately as possible. If a small backlash is allowed in gasoline analogues, then everything is different here. As a result, at the very beginning of the introduction of technology, diesel units were installed only on large machines. It is enough to remember the same trucks of the beginning of the last century.

History of creation

It is hard to imagine, but the first efficient diesel engine designed the engineer Rudolph Diesel back in the XIX century. Then the usual kerosene was used as fuel.

With the development of technology, scientists began to experiment. As a result, what kind of fuels were not used to achieve better results. For example, for some time the motors were refueling with rapeseed oil and even crude oil. Of course, such an approach could not give truly serious achievements.

Perennial research led scientists to the idea of \u200b\u200busing fuel oil and diesel fuel. Their low cost and good flammability made it possible to make serious competition with gasoline analogues.

Attention! Mazut and diesel engines are made without the use of complex technological processes. This is the key to their low price. In fact, they are a by-product from oil refining.

Initially, the fuel injection system in the device of diesel engines was extremely imperfect. It did not allow the use of aggregates in machines that worked at high speeds.

The first samples of cars equipped with diesel engines appeared in the 20s of the last century. It was cargo and public transport. Before that, the motors of this class were used only on stationary machines or ships.

Only 15 years later the first cars appeared, which worked at the expense of a diesel engine. Despite this, a very long diesel, being powerful and having immunity to detonation, was not widespread in the automotive industry. The fact is that in the presence of significant advantages in the unit there was a number of disadvantages, such as increased noise when working and high weight.

Only in the 70s, when the prices of oil began to grow, everything changed dramatically. Automakers and consumers rushed their eyes to cars, in their device with diesel engines. It was then that for the first time there were compact diesel engines.

Diesel engine

Device diesel engine

The device of the diesel engine consists of four main elements:

• cylinders
• pistons
• fuel nozzle
• inlet and exhaust valve.

Each design element performs its task and has its own structural features. In the development process, this technology was supplemented by many details, which allowed much more productivity to achieve much of them:

• fuel burner,
• intercooler.

Each of these parts made it possible to significantly increase the efficiency of the diesel engine.

Principle of operation

The diesel engine is working at the expense of compression. Due to this process, the pressure fluid enters the combustion chamber. Injector nozzles are used by band meals.

Important! Fuel gets inside only when the air has the desired compression force and high temperature.

The air should be hot enough to fuel ignites. Before you get inside the liquid passes through a series of filters that delay alien particles that can harm the system.

To understand the principle of operation of the diesel engine, you need to consider the entire process of feeding and igniting fuel from the beginning to the end. At the initial stage, the air is served through the inlet valve. In this case, the piston moves down.

Some intake systems are additionally shutdown with dampers. Thanks to them, there are two channels in the design, through which the air falls inside. As a result of this process, there is a twisting of air masses.

Attention! The intake dampers can only be open at a high rotational speed of the crankshaft.

When the piston reaches the top point, Air is compressed 20 times. The limit pressure is about 40 kilograms per square centimeter. At the same time, the temperature reaches 500 degrees.

The nozzle is injected into the fuel inside the chamber in a strictly specified quantity. Inflammation occurs exclusively due to high temperature. It is this fact that explains that there is no candles in the diesel engine device. Moreover, the ignition system is missing as such.

The absence of a throttle design allows you to develop a large torque. But the number of revolutions is at a stable low mark. During one cycle, several injections of the liquid can be carried out.

Down the piston pushes the pressure of expanding gases. The result of this process is what the crankshaft turns. The link in this microprocession is the connecting rod.

Having reached the bottom point, the piston rises again, thereby pushing the exhaust gases. They go out through the exhaust valve. Such a working cycle repeats time after a diesel engine.

To reduce the percentage of soot in gases, which extend through the exhaust system there is a special filter. It allows to significantly reduce the harm caused by ecology.

Additional nodes

How turbine works

The turbine in the diesel engine device allows to significantly increase the overall performance of the system. Nevertheless, automotive engineers did not immediately come to this decision.

The impetus to the creation of the turbine and the introduction of it in the general device of the diesel engine was the fact that fuel does not have time to completely burn until the piston moves to the dead point.

The principle of operation of the turbine on a diesel engine is that this structural element allows you to achieve full combustion of fuel. As a result, the motor power increases significantly.

The turbocharger device consists of such elements:

• Two covers - one is attached to the turbine, the second on the compressor.
• Bearings are support of the node.
• The protective function performs a steel grid.

The whole cycle of the turbine of the diesel engine consists of the following steps:

1. Air is absorbed inside with the compressor.
2. A rotor connects in motion due to the turbine rotor.
3. Intercooler cools the air.
4. Air passes several filters and gets inside through the intake manifold. At the end of this action, the valve closes. Opening occurs when the working stroke is completed.
5. Through the turbine of the diesel engine are spent gases, thereby putting pressure on the rotor.
6. At this stage, the speed of rotation of the turbine of the diesel engine can reach about 1,500 revolutions per second. It makes rotating the compressor rotor by means of a shaft.

This cycle is repeated once by time. Thanks to the use of the turbine, the power of the diesel engine is growing.

Important! Due to the cooling, the air density increases.

An increase in air density allows it to be supplied in much larger amounts inside the engine. An increase in flow contributes to the fact that the fuel inside the system is completely combusting.

Interculler and nozzle

During compression, not only air density increases, but also its temperature. Unfortunately, it greatly affects the durability of the diesel engine. Therefore, scientists were invented such a device as an intercooler. It effectively reduces the temperature of the air flow.

Important! The intercoooller works with air cooling by heat exchange.

In the device there may be one or two nozzles. Their task is to spray and dispense fuel. The principle of operation of the diesel engine nozzle is implemented due to the cam, which departs from the camshaft.

Attention! Diesel engine nozzles operate in pulse mode.

RESULTS

Due to the use of new technologies and additional nodes, the diesel engine allows you to achieve an amazing performance indicator from fuel combustion. This indicator reaches 40-50 percent. Which is almost twice as much as in the gasoline analogue.

Features of the diesel engine, such as efficiency and high torque, make it a preferred option. Modern diesel engines are close to gasoline engines for noise, while maintaining advantages in economy and reliability.

Design and structure

The design of the diesel engine does not differ from the gasoline - the same cylinders, pistons, rods. True, the valve parts are reinforced to perceive high loads - because the degree of compression of the diesel engine is much higher (19-24 units against 9-11 at the gasoline motor). This explains the high weight and dimensions of the diesel engine in comparison with gasoline.

In principle, the difference is to form a mixture of fuel and air, its ignition and combustion. At the gasoline motor, the mixture is formed in the inlet system, and the spark plug is flammable in the cylinder. In diesel engine fuel supply and air takes place separately. Initially, air enters the cylinders. At the end of the compression tact, when it is heated to a temperature of 700-800 o C, into the combustion chamber by nozzles, the diest pressure is injected under high pressure, which is almost instantly self-propagated.

Mixing formation in diesels occurs in a very short period of time. To obtain a combustible mixture capable of quickly and completely burned, it is necessary that the fuel is sprayed at possible smaller particles and that each particle has sufficient air for complete combustion. For this purpose, fuel in the cylinder is injected with a pressure injector, several times higher than air pressure during compression tact in the combustion chamber.

In Diesels use undefined combustion chambers. They are a single amount limited to the bottom piston 3. and the surfaces of the head and walls of cylinders. For better stirring of fuel with air, the shape of an undivided combustion chamber adapts to the form of fuel torches. Deepening 1.Performed in the bottom of the piston contributes to the creation of a vortex air movement.

Finely sprayed fuel injected from nozzle 2. Through several holes aimed at certain depths. In order for the fuel completely burned and the diesel, it has the best capacity and economic indicators, the fuel should be injected into the cylinder until the piston arrives in the VMT.

Self-ignition is accompanied by a sharp increase in pressure - hence the increased noise and stiffness of the work. Such organization of the workflow allows you to work on very poor mixtures, which determines high efficiency. Environmental characteristics are also better - when working on poor mixtures, emissions of harmful substances are less than that of gasoline engines.

The disadvantages include increased noise and vibration, lower power, cold start difficulties, problems with winter diesel art. Modern diesel engines are not so obvious.

Diesel fuel must meet certain requirements. The main fuel quality indicators are purity, low viscosity, low self-ignition temperature, high cetane number (not lower than 40). The greater the cetane number, the lower the period of delay in self-ignition after the injection of it in the cylinder and the engine works softer (without stuffs).

Types of diesel engines

There are several types of diesel engines, the difference between which is concluded in the combustion chamber design. In diesel engines with an undivided combustion chamber - They call them diesel engines with direct injection - fuel is injected into the epipper space, and the combustion chamber is performed in the piston. Immediate injection is used on low-speed engines of a large working volume. 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 (TNLD) with electronic control, two-stage fuel injection and optimization of the combustion process, it was possible to achieve a sustainable diesel operation with an undefined combustion chamber on turns to 4500 rpm, improving efficiency, reduce noise and vibration.

The most common is another type of diesel - with a separate combustion chamber. The fuel injection is not carried out in the cylinder, but in an additional chamber. A vortex chamber is used in the head of the cylinder block and connected to the cylinder with a special channel so that when compressing the air, falling into a vortex chamber, it is intensively twisted, which improves the process of self-ignition and mixing. Self-ignition begins in the vortex chamber, and then continues in the main combustion chamber.

At a separate combustion chamber, the rate of increase in the cylinder is reduced, which helps to reduce noise and increase maximum revolutions. Such engines make up most among those installed on modern cars.

Fuel system device

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

The main elements are: high pressure fuel pump (TNVD), nozzles and fuel filter.

TNVD

The pump is designed to supply fuel to the nozzles by a strictly defined program, depending on the mode of operation of the engine and the driver's action. In essence, modern TNLD combines the functions of a complex system of automatic control of the engine and the main executive mechanism that worries the chauffeur command.

Pressing the gas pedal, the driver does not increase the fuel supply directly, but only changes the program of operation of the regulators, which themselves change their feed on strictly certain dependencies on the number of revolutions, pressure pressure, the position of the regulator lever, etc.

On modern cars applied TNVD distribution type. The pumps of this type were widespread. They are compact, characterized by high uniformity of fuel supply over cylinders and excellent work at high speed due to the speed of regulators. At the same time, they impose 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.

Nozzle.

Another important element of the fuel system is the nozzle. It together with the pump provides a strictly dosed amount of fuel into the combustion chamber. Adjusting the pressure opening pressure determines the operating pressure in the fuel system, and the type of the sprayer determines the shape of the fuel torch, which is important for the process of self-ignition and combustion. Usually the nozzles of two types are used: with a font or multi-dimensional distributor.

The engine nozzle works in difficult conditions: the sprayer needle performs reciprocating movements with a frequency of half less than the engine turnover, and at the same time the sprayer directly contacts the combustion chamber. Therefore, the nozzle sprayer is made of heat-resistant materials with particular accuracy and is a precision element.

Fuel filters.

Fuel filter, despite its simplicity, is an essential element of a diesel engine. Its parameters, such as filtering subtlety, bandwidth must strictly correspond to a specific type of engine. One of its functions is the separation and removal of water.For which the lower drain plug is usually served. On the top of the filter housing, a manual paging pump is often installed to remove air from the fuel system.

Sometimes a fuel filter electrically heating system is installed, which allows you to slightly facilitate the start of the engine, which prevents the filter clogging by paraffins formed during the crystallization of diesel fuel in winter conditions.

How is the start?

Cold diesel start provides preheating system. To do this, electrical heating elements are inserted into the combustion chamber - incandescent candles. When you turn on the ignition of the candle in a few seconds, it is heated to 800-900 o C, thereby providing air heating in the combustion chamber and facilitating the fuel ignition. About the operation of the system driver in the cockpit signals a control lamp.

The population of the control lamp indicates a ready-to-launch. The power supply from the candle is automatically removed, but not immediately, and after 15-25 seconds after starting to ensure the steady operation of the immense engine. Modern preheating systems provide a slight start of a working diesel to a temperature of 25-30 o C, of \u200b\u200bcourse, provided that the season of oil and diesel fuel matching.

Turbocharged and Common-Rail

An effective means of increasing the capacity is turbocharging. It allows you to submit an additional amount of air into cylinders and the result increases the power. The pressure of the exhaust gases of diesel is 1.5-2 times higher than that of a gasoline engine, which allows the turbochargers to ensure an effective supervision from the lowest revolutions, avoiding the failure of the failure inherent in gasoline turboys.

Computer control of fuel supply made it possible to inject it into the combustion chamber of the cylinder with two precisely dosed portions. First, the tiny, only about a milligram, a dose, which, when combustion, increases the temperature in the chamber, and follows the main "charge". For a diesel engine, the engine with fuel ignition from compression is very important, since the pressure in the combustion chamber increases more smoothly, without a "jerk". As a result, the motor works softer and less noisy.

As a result, in diesel engines with the COMMON-Rail system, fuel consumption is reduced by 20%, and the torque on small crankshaft turns increases by 25%. Also reduced content in exhaust soot and the noise of the motor is reduced.

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 Start

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.