Over the past ten years, diesel technologies have developed rapidly. Most of the modern cars that are manufactured in Europe are manufactured with diesel engines. Of course, the principle of work this device did not change. However, modern diesel engine is much quieter. He became ecologically cleaner. In the distant past, severe rag in, thick black smoke remained nasty smell When the device is working. So, what is the principle of operation of the diesel engine?
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
diesel engine should be attributed elevated level noise, vibration, small 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 applies optional equipment. 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 fuel mixture, injected into the compartment, mixed well 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 while flowing into additional camar From the air cylinder, as well as to the reverse process: move 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.
The times have long passed when a diesel engine was considered largely a compromise "smaller brother" of gasoline engines in the civil engine industry.
Due to the peculiarities of diesel fuel, this type has a number of obvious advantages.
The strengths are so apparent that even domestic constructors broke their heads to introduce this technology.
Now such motors have a NEXT Gazelle, UAZ Patriot. Moreover, there were attempts to install a diesel engine on the Niva. Unfortunately, the release was limited to small export parties.
Positive factors allowed the diesel engine to gain popularity in each of the automotive segments. We are talking about a four-stroke configuration, since the two-stroke diesel engine has not received widespread use.
Design
The principle of operation of the diesel engine is to transform the reciprocating movements of the crank-connecting mechanism into mechanical work.
The method of preparation and ignition of the fuel mixture is something that a diesel engine differs from gasoline. In the combustion chambers of gasoline engines, prepared in advance fuel-air mixture is flameable using the spark ignition candle.
The peculiarity of the diesel engine is that the mixing formation occurs directly in the combustion chamber. The working clock is carried out by injection under the huge pressure of the dosage portion of fuel. At the end of the compression tact, the reaction of heated air with diesel fuel leads to ignition of the working mixture.
A two-stroke diesel engine has a narrower scope of application.
The use of single-cylinder and multi-cylinder diesel engines of this type has a number of constructive flaws:
- ineffective blowing of cylinders;
- increased oil consumption with active use;
- located in piston rings in high-temperature exploitation and other.
Two-stroke diesel engine with opposite placement piston group It has high initial cost and is very complicated in service. The installation of such an aggregate is appropriate only on maritime courts. In such conditions, due to the small dimensions, low mass and greater power during identical revolutions and working volume, the two-stroke diesel engine is more preferable.
Single-cylinder aggregate internal combustion widely used in household As an electric generator, engine for motoblocks and self-propelled chassis.
This type of energy obtaining imposes certain conditions on a diesel engine device. It does not need fuel pump, candles, ignition coil, high-voltage wires and other nodes, vital for normal work Gasoline DVS.
In the discharge and supply of diesel fuel are involved: fuel pump High pressure and nozzle. To facilitate cold start, modern motors use gas candles, which pre-heated air in the combustion chamber. In many cars, auxiliary pump is installed in the tank. Task of the fuel pump low pressure In order to pump fuel from the tank to the fuel equipment.
Development ways
Innovation of the diesel engine consist in evolution fuel equipment. Designer's efforts are aimed at achieving the exact moment of injection and maximum spraying of fuel.
The creation of fuel "fog" and dividing the injection process on the phases made it possible to achieve greater efficiency and increase in power.
The most archaic specimens had a mechanical TNVD and a separate fuel line to each nozzle. The engine device and that type have had great reliability and maintainability.
The further path of development was complicated by the TNLD diesel engine. It has changed injection moments, many sensors and electronic processes control. At the same time, all the same mechanical nozzles were used. In such a type of design, the fuel injected pressure was from 100 to 200 kg / cm².
The next step was the introduction of the COMMON RAIL system. A fuel ramp appeared in the diesel engine, where pressure is up to 2 thousand kg / cm². TNLD such motors have become much easier.
The main structural complexity lies in the nozzles. It is with their help that the moment is regulated, the pressure and number of injection steps. System nozzles battery type Very demanding of fuel quality. Enterprise such a system leads to a rapid failure of its main elements. Diesel engine S. COMMON RAIL. It works quietly, consumes less fuel and has a greater power. For all this you have to pay a smaller resource and a higher cost of repair.
An even more high-tech is the system using pump-nozzles. This type of nozzle connects the functions of injection pressure and spraying the fuel. The parameters of the diesel engine with pump-nozzles are an order of magnitude higher than analog systems. However, as the cost of maintenance and requirements for fuel quality.
The importance of configuration of turbines
Most modern diesel engines are equipped with turbines.
Turbocharging is effective method Increase the power characteristics of the car.
Due to elevated pressure exhaust gases, The use of turbines in a pair with diesel engine will noticeably increase the rigging and reduces fuel consumption.
The turbine is far from the most reliable car unit. More than 150 thousand km they often do not go. This is perhaps its only minus.
Thanks to the electronic motor control unit (ECU), a diesel engine is available chip tuning.
Advantages and disadvantages
There are a number of factors that are profitable distinguish diesel engines:
- efficiency. Efficiency of 40% (up to 50% with the use of turbocharging) is simply an inaccessible indicator for the gasoline fellow;
- power. Virtually the entire torque is available at the lowest revs. The turbocharged diesel engine does not have a pronounced turboyama. Such richness allows you to get real driving pleasure;
- reliability. Mileage of the most reliable diesel engines reaches 700 thousand km. And all this without tangible negative consequences. Thanks to its reliability, diesel engines put on special equipment and trucks;
- ecology. In the struggle for the safety of the environment, the diesel engine is superior to gasoline engines. A smaller amount of ejected CO and the use of exhaust recycling technology (EGR) bring minimum harm.
Disadvantages:
- cost. The equipment equipped with a diesel engine will cost 10% more than the same model with a gasoline unit;
- complexity and high cost of service. KVS nodes are made of more durable materials. The complexity of the engine and fuel equipment requires high-quality materials, newest technologies and great professionalism in their manufacture;
- bad heat transfer. The large percentage of efficiency means that smaller energy losses occur when combustion of fuel. In other words, less heat is allocated. IN winter time The years of operation of the diesel engine for short distances will adversely affect its resource.
Considered minuses and advantages do not always balance each other. Therefore, the question of which engine is better, will always stand. If you are going to become the owner of such a car, consider all the features of his choice. It is your requirements for a power plant that will be the factor that will solve that better: gasoline or diesel engine.
Should I buy
New diesel carsmobile is the type of acquisition that only joy will bring. Playing the car with high-quality fuel and making it according to regulatory prescriptions, you will not regret buying 100%.
But it is worth considering the fact that diesel cars are an order of magnitude more expensive than its gasoline analogues. You can compensate for this difference and subsequently save only when you overcome a big kilometer. Overpay with the purpose of passing a year to 10 thousand km. Simply not advisable.
The situation with used cars is a bit different. Despite the fact that diesel engines are distinguished by a large margin of strength, with time, complex fuel equipment requires increased attention. Prices for spare parts for a diesel engine of over 10 years truly depressing.
Cost TNVD on budget car A class of 15 years old can plunge into some car enthusiasts. To the choice of cars with a mileage of over 150 thousand. It must be treated very seriously. Before buying it is better to make comprehensive diagnostics in a specialized service. Since the low quality of domestic diesel fuel is very adversely affected by the resource of the diesel engine.
In this case, to decide which engine is better to give preference, the manufacturer's reputation will help. For example, the model Mercedes-Benz OM602 is rightfully considered one of the most reliable diesel engines in the world. Buying a car with a similar power unit will be a beneficial investment for many years. Many manufacturers have similar "successful" models power plants.
Myths and delusion
Despite the prevalence of cars with a diesel engine, the people still have prejudices and misunderstanding. "Tharachtitis, it does not warm in winter, and in a large frost you will not get started, in the summer it does not go, and if something worries, you need to repair everything, which for space money will repair everything," - about such words can sometimes hear from "experienced" motorists. All this is the echoes of the past!
- Thanks modern technologies, only idling rack allows you to distinguish diesel engines from gasoline. In motion, when the noise of the road is growing, the difference is not noticeable.
- To improve the launch and warm-up in the cold season, various auxiliary systems are used in modern cars. In view of increasing popularity, the number of services specialized in the maintenance of a diesel engine is constantly increasing.
- It is the opinion that the engine running on a diesel engine is difficult to force. This is true if we are talking about the modifications of the cylindrophone group. At the same time, chip tuning diesel engine is good way Increase its power characteristics without deterioration of resource.
It is worth remembering that the principle of operation of the diesel engine is entirely aimed at achieving efficiency and reliability. Do not require transcendental dynamic indicators from such internal engine.
Symptoms and causes of faults
- The poor launch of the diesel engine is on the cold, and after a long downtime - means poorly working glow candles, air in the system, the check valve pours fuel pressure, poor compression, discharged battery;
- increased noise, increased consumption and black smoke from the exhaust pipe - means clogging or wear of the sprayers and nozzles, incorporate injection angles, a dirty air purification filter;
- disappeared the power of the diesel engine - means the absence of compression, failure of the turbine, clogging fuel and air filters, incorrect injection advance angles, polluted valve EGR;
- gray or white smoke from exhaust, elevated oil consumption - means a cracking of a cylinder head or punched gasket GBC. (The cooling fluid is due, and an emulsion appears in the oil), a turbocharger fault.
Proper operation
Improper operation can destroy even the most reliable motor.
Extend the resource of the diesel engine, and enjoy the ownership of the car will help you with the execution of simple rules:
- diesel engines with turbocharging are very demanding of the quality of oil and fuel. Pour only the oil that meets the requirements installed for your DVS. Refuel only on proven gas stations;
- conduct preheating In accordance with the stated manufacturer standards. In this case, you will not have any problems with the launch of the diesel engine during the cold season. Operation of an aggregate with an incorrectly operating nozzle can later lead to expensive repair of the FROS;
- after active trips, the turbine needs cooling. Do not shuffle the motor immediately. Let him work for a while on idling;
- avoid running "from the Tolkach". This method of revitalizing the motor can cause great harm to the crystal-connecting mechanism of your engine.
Both types of engines have not only advantages, but also cons. The main goal of the car is to meet your requirements, it does not matter, the gasoline or diesel engine is installed in it. What is better to suit you, depends only on individual preferences.
Modern innovative technologies and progressive marketing allow people to choose from cars that they can afford. We still have to compromise and sacrifice separate parameters. Especially this trend is noticeable in the process of evolution of diesel cars.
Good day. I think many will be interested in this topic. Advantages and disadvantages ... all below.
In 1890, Rudolph Diesel developed the theory of "economical thermal engine", which, thanks to strong compression in the cylinders, significantly improves its effectiveness. He received a patent for his engine on February 23, 1893. The first functioning sample was built by Diesel by the beginning of 1897, and on January 28 of the same year he was successfully tested.
Interestingly, the diesel in his book instead of our usual diesel fuel, as ideal fuel, described coal dust. Experiments showed the impossibility of using coal dust as fuel - primarily due to the high abrasive properties.
But the theory of diesel engine was also considered ecroyd stewart. He did not consider the benefits of working from a high compression, he simply experimented with the possibilities of exclusion from the spark plug engine, i.e., he did not pay attention to the greatest advantage - fuel efficiency. Perhaps it was the reason that the term "diesel engine", "diesel engine" or simply "diesel", etc., is currently used, etc. Rudolph Diesel theory has become the basis for creating modern engines With ignition from compression. In the future, about 20-30 years, such engines were widely used in stationary mechanisms and power plants of maritime courts, however, the fuel injection systems that existed then did not allow to apply diesel engines in highly engaged units. A small speed of rotation, the considerable weight of the air compressor necessary for the operation of the fuel injection system made it impossible to use the first diesel engines on the vehicle.
In the 20s of the 20th century, German engineer Robert Bosch has improved the built-in high-pressure fuel pump, a device that is widely used and in our time. Using hydraulic system For injection and fuel injection, it has made it possible to abandon a separate air compressor and made it possible to further increase the speed of rotation. Survived in this form, the high-speed diesel began to enjoy increasingly popular as a power unit for auxiliary and public transport, but arguments in favor of engines with electric ignition (the traditional principle of work, lightness and a small price of production) allowed them to enjoy in great demand for installation on passenger and small trucks, in the 50s - 60s diesel is established in large quantities on trucks and automobiles, and in the 70s after A sharp increase in fuel prices, worldwide manufacturers of inexpensive small passenger cars pay serious attention to it.
Work principles:
Four-stroke cycle.
For first Tact (inlet tact, piston goes down) Fresh air portion is drawn into a cylinder through an open intake valve.
For second Tact (compression tact, piston goes up) intake and exhaust valvethe closed conditions are compressed in the volume of about 17 times (from 14: 1 to 24: 1), i.e. the volume becomes less than 17 times compared with the total volume of the cylinder, and the air becomes very hot.
Immediately before start third Takta. (Stroke clock, the piston goes down) fuel is injected into the combustion chamber through the nozzle sprayer. When injection, the fuel is sprayed into small particles, which are evenly mixed with compressed air to create a self-propagating mixture. Energy is released during combustion when the piston starts its movement in the working stroke tact.
Exhaust valve opens when starts fourth tact (Tact of release, piston goes up), and exhaust gases pass through the exhaust valve.
Two-stroke cycle.
The piston is in the lower dead point and the cylinder is filled with air. During the stroke of the piston up, the air is compressed; Near the upper dead point, the fuel injection occurs, which is self-propagated. Then there is a working stroke - combustion products expand and transmit the energy of the piston, which moves down. Near the bottom dead point, purge - combustion products are replaced by fresh air. The cycle is completed.
For the purge at the bottom of the cylinder, purge windows are made. When the piston is downstairs, the windows are open. When the piston rises, it overlaps the windows.
Since in a two-stroke cycle, working turns occur twice as often, then you can expect a double increase in power compared to the four-stroke cycle. In practice, this is not possible to implement, and the two-stroke diesel is more powerful than 1.6 - 1.7 times in the amount of a four-stroke maximum.
Currently, two-stroke diesel engines are widely used on large marine ships with direct (unprecedented) propeller propeller. If it is impossible to increase the speed of rotation, the two-stroke cycle is advantageous; Such low-speed diesel engines have power up to 100.000 hp.
Pros and cons.
Benzi. new engine It is rather ineffective and able to convert only about 20-30% of fuel energy into useful work. A standard diesel engine, however, usually has a utility coefficient of 30-40%, turbocharging diesel engines and an intermediate cooling over 50% (for example, MAN S80ME-C7 spends only 155 grams per kW, reaching an efficiency of 54.4%). The diesel engine due to the use of high pressure injection does not impose requirements for fuel volatility, which allows the use of low-grade heavy oils in it.
Diesel engine can not develop high revs - The mixture does not have time to burn in the cylinders. This leads to a decrease in the electrical power of the engine per 1 liter of volume, and hence, to a decrease in the specific power per 1 kg of the engine mass.
Diesel engine does not have throttle valve, Power control is carried out by adjusting the amount of injected fuel. This leads to a lack of a reduction in pressure in cylinders on low revs. 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, most trucks are currently equipped with diesel engines.
Explicit disadvantages of diesel engines are the need to use a high-power starter, clouding and frozen summer diesel fuel low temperatures, difficulty in repairing fuel equipment, since high pressure pumps are devices made with high accuracy. Also, diesel motors are extremely sensitive to fuel contamination with mechanical particles and water. Such pollution is very quickly derived fuel apparatus. Repair of diesel engines, as a rule, significantly more expensive repair 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 more even torque in their operating range. Environmental indicators of diesel engines significantly inferior to recently gasoline engines. On classical diesel engines with a mechanically controlled injection, only oxidative exhaust gas neutralizers (catalyst in the spacious) operating at the temperature of the exhaust gas over 300 ° C, which oxidize only CO and CH to the carbon dioxide and water harmless to humans. 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 diesel engines of the so-called "COMMON-Rail" system. In this type of diesel engines, the fuel injection is carried out by electrically controlled nozzles. The control of the control electrical pulse performs the electronic unit Controls receiving signals from 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, and according to a number of complexity parameters and significantly exceeds it. For example, if the fuel pressure in the nozzles of a conventional diesel engine with a mechanical injection ranges from 100 to 400 bar, then in the newest systems "Common-Rail" it is in the range from 1000 to 2500 bar, which entails considerable problems. Also, the catalytic system of modern transport diesel engines is much more complicated by gasoline engines, since the catalyst must "be able to" work under the conditions of an unstable composition of exhaust gases, and in cases where the introduction of the so-called " squeeze 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, the portion of the soot is not always oxidized, and remains in the "Saint Filter", so the control unit program periodically translates the engine to the "squeezing filter" cleaning mode by the so-called "posting", that is, the injection of an additional amount of fuel into the cylinders at the end of the combustion phase for the purpose Raise the temperature of the gases, and, accordingly, clean the filter by burning the accumulated soot. The de facto standard in the designs of transport diesel engines was the presence of a turbocharger, and in recent years - and the so-called "intercooler" - that is, the devices cooling the air compressed by the turbocharger. 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.
Well, in the late most interesting. Myths about diesel engines.
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 engine volume. This is talking about the diesel prototype Audi R10, which won the 24-hour race in Le Mana, and new bMW engineswhich are not inferior in power atmospheric (without turbocharging) gasoline and at the same time possess a huge torque.
The diesel engine is too loud.
Properly configured diesel is only a bit "louder" gasoline, which is noticeable only at idle. There are practically no difference in the working modes. Loudly operating engine indicates not properly operation and possible faults. In fact, old diesel engines with mechanical injection are really distinguished by a very rigid job. Only with the advent of rechargeable fuel Systems High pressure ("Common-Rail") in diesel engines managed to significantly reduce the noise, primarily due to the separation of one injection pulse into several (typically - from 2 to 5 pulses).
The diesel engine is much more economical.
The times when diesel fuel was treated three times cheaper than gasoline, long ago passed. Now the difference is only about 10-30% at the price of fuel. Despite the fact that the specific heat of the combustion of diesel fuel (42.7 MJ / kg) is less than that of gasoline (44-47 MJ / kg), 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 indeed much more than gasoline and can reach 400-600 thousand kilometers. [Source is not specified 211 days] Spare parts for diesel engines are also somewhat more expensive as the cost of repair. Despite all the reasons for all the above, the cost of operation of the diesel engine will be not much less operation than that of the gasoline. [Source is not specified 211 days]
The diesel engine is badly started in the frost.
With proper operation and preparation for winter, the engine problems will not arise. For example, a diesel engine VW-Audi 1.9 TDI (77 kW / 105 hp) is equipped with a quick launch system: heating of incandescent candles up to 1000 degrees is carried out for 2 s. The system allows you to start the engine in any climatic conditions without preheating.
The diesel engine cannot be converted to the use of cheaper gas as fuel.
The first examples of the operation of diesel engines on cheaper fuel - Gaza were pleased in 2005, Italian tuning firms that were used as fuel methane. Currently, options for the use of gas-digessels on propane were successfully established, as well as radical solutions for the refurbishment of a diesel engine to the gas engine, which has an advantage over a similar engine, refurbished from gasoline, due to its initially higher compression.
And what do you say about the diesel engine?)
Greetings you friends! Diesel power unit has long won love and respect in the circle of motorists! It is more economical, more reliable, and the total efficiency is much higher than the gasoline fellow. However, a more complex device and the principle of operation of the diesel engine do not give many domestic chauffs to decide on the purchase of a car of this type. It is not strange, makes pay attention to the cost of maintenance of vehicles and it is right! But still, in order to dispel the fears of colleagues, today I will try in understandable form to describe all the features of such an aggregate. But about everything, as usual in order ...
A little prehistory
The first motor of this type was created by the French engineer Rudolph Diesel, who lived in the era of the XIX century. As you know, the master did not think long over the title of his invention and went in the footsteps of great inventors, nicknamed him with his last name. The engine operated on kerosene, and was used exclusively among ships and stationary machines. Why? Everything is very simple, huge weight and increased noise of the engine, did not allow to increase the spectrum of its application.
And so it was up to 1920, when the first copies of a substantially modernized diesel engine began to apply in public and cargo transport. True, only 15 years later, the first models of passenger cars operating on diesel fuel appeared, but the presence of all the same minuses did not allow the use of the power unit everywhere. Only in the 70s, the light saw really compact diesel engines, by the way, many experts bind this event to a sharp rump of oil prices. Whatever it was, a diesel power unit during his formation on what did not work. Experimentators lily in it all the way will fall under hand: rapeseed oil, raw oil, fuel oil, kerosene and finally die away. Nowadays, we all see what it led - against the background of expensive gasoline, Diesel conquers not only Europe, but the whole world!
Design features
The device of a diesel engine, by and large has not so many differences in comparison with the gasoline analogue. This is all the same piston inner combustion motor, in which fuel ignition is carried out not by sparking, but by compression or heating. In its design, several main elements can be distinguished:
- Pistons;
- Cylinders;
- Fuel injectors;
- Glow candles;
- Valve intake and graduation;
- Turbine;
- Intercooler.
For comparison: the efficiency of the gasoline engine is about 30%, in the case of a diesel version, this indicator increases to 40%, and with a turbocharger and in all up to 50%!
Moreover, the functioning schemes are also very similar to each other. Only the processes for creating the fuel and air mixture and its combustion are distinguished. Well, another global difference is the strength of the details. There is such a moment a much higher level of compression levels, because if there is a small backlash between the details in the "lighters", then in the dieselle everything should be as tight as possible.
Principle of operation
Let's finally understand how the diesel engine works. If we talk about a four-stroke version, here you can observe a combustion chamber separate from the cylinder, which is nonethelessly associated with a special channel. This type of engines, advanced to the masses, much earlier than a modification with two tactics, due to the fact that they were quieter and had an increased range of revolutions. If you follow logic, it becomes clear if 4 clocks, then, accordingly, the working cycle consists of 4 phases, consider them.
- Inlet - when turning crankshaft In the area of \u200b\u200b0-180 degrees, the air enters the cylinder through the intake valve, which opens by 345-355 degrees. Simultaneously with the intake, the exhaust valve opens, when the crankshaft turn is 10-15 degrees.
- Compression - moving up at 180-360 degrees, the piston compresses the air at 16-25 times, in turn at the beginning of the clock at 190-210 degrees, the intake valve is closed.
- Working - When the tact is just beginning, the fuel is mixed with hot air and flammifies, it naturally happens to achieve a piston of a dead point. At the same time, combustion products are distinguished, which put pressure on the piston and it moves down. Please note that the gas pressure is constantly so the fuel combustion lasts exactly as much as the diesel engine nozzle supply fluid. Precisely because of this, the larger torque is developing in comparison with petrol aggregates. All this action is carried out at 360-540 degrees.
- Issue - When the crankshaft rotates 540-720 degrees, the piston moving up extrudes the exhaust gases through the open exhaust valve.
The principle of operation of the two-stroke diesel engine is characterized by faster phases, a single gas exchange and direct injection process. For those who are not in the subject remember: in such structures, the combustion chamber is directly in the piston, and the fuel enters the space above it. When the piston moves down, the combustion products leave the cylinder through the exhaust valve. Next, the inlet valves will be reached and fresh air comes. When the piston moves up, all valves are closed, compression occurs at this time. The fuel is injected with sprayers and its ignition begins until the piston of the upper dead point is reached.
Optional equipment
If you drop the ICA itself to the side, the whole range of quite trained assistants come to the general plan. Consider the main professionals!
Fuel system
The device of the fuel system of the diesel engine is much more complicated in gasoline modifications. This nuance is explained easily and simply - the requirements for the pressure of the supplied fuel, quantity and accuracy are very high, you know why. TNLD diesel engine, fuel filter, nozzles of their sprayers - all these are the basic elements of the system. Separate article deserves not only equipment, but also the device fuel filter. Perhaps soon we will analyze under the microscope and their.
Turbochards.
The turbine on the diesel engine significantly increases its performance due to the fact that fuel is fed under high pressure and, accordingly, completely burns out. The design of this unit in principle is not so complicated, it consists of only two casing, bearings and a protective grid of metal. The principle of operation of the turbine of the diesel engine is as follows:
- The compressor to which one casing is connected sucks the air into the turbocharger.
- Next, the rotor is activated.
- After, it comes to cool the air, an intercooler copes with this task.
- After passing several filters on its path, the air through the intake manifold enters the engine, after which the valve closes, and its subsequent opening occurs at the final stage of the working stroke.
- Just then through the turbine, the motor leave the exhaust gases, which also have a certain pressure on the rotor.
- At this point, the speed of rotation of the turbine can reach 1500 revolutions per second, and the rotor rotates through the shaft.
The cycle of the turbine operating power aggregate Repeats once over time and exactly due to such stability, the power of the motor grows!
Injectors and intercooler
The principle of operation of the intercooler, as well as the nozzles, and indeed their purpose, of course differ fundamentally. The first, by heat exchange reduces the air temperature, which in the hot condition strongly affects the durability of the engine. On the nozzle, the task in the dosage and spraying of fuel.
It functions in a pulse mode due to the cam, departing from the camshaft and the actual sprayers.
Operating temperature Diesel
Do not be afraid if there are no familiar 90 degrees on the instrument panel. The fact is that the working temperature of the diesel engine is quite specific and depends on concrete brand Car, actually motor and thermostat itself. So, for "Volkswagen" a normal value will be the mark within 90-100 degrees, then the ordinary "Mercedes" operates at 80-100, and "Opel" in general in the region of 104-111 degrees. Domestic truck "KAMAZ", for example, works at 95-98 degrees.
Whatever working temperature has not been at your power unit, one obvious - the Motors on the diesel fuel are relevant today, more than ever. Do not believe me? Look around, today you can even meet a diesel engine on "Niva" and I will tell you, the case is not a single. Already from this we can conclude - such a motor is much better than gasoline.
Yes, in high-speed qualities, it is hardly possible to compare with gasoline, although modern models with turbines can definitely create competition.
If you change the car, and even more the engine no desire, I recommend own hands wash the engine, because we do it is not so often, as the procedure looks like, I described. In general, I expressed my opinion, waiting for your comments! All the best!
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 practical use Such an engine was limited: he inferior to steam machines of that 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 divided exhaust and fresh air charge is also impossible, so part of the air is lost, leaving right in 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 two-stroke engine Working runs are twice as much as in four-stroke, but due to the presence of purging the two-stroke diesel is more powerful than 1.6-1.7 times.
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 typical for large long-term ship engines, often - double action, the stroke of the piston 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. Detonation of a mixture of diesel fuel with air in a pier fuel tank In terms of its consequences, it is comparable to the explosion of ammunition, in particular, the T-34 tanks, it led to the rupture of welds and knock out the top front part of the armor. 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.
At its heart, the design of the diesel engine is similar to the design. 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 locomotives, dieselosis, diesel trains, autoderees) and firefight (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 is to convert a diesel engine with a decrease in the degree of compression, the installation of the ignition system and, in fact, with the construction instead of diesel gas engine on its basis.
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.
