How does a diesel car engine work?
Conventional wisdom holds that diesel engines produce a lot of noise, smell bad, and don't produce the required power. They are considered to be suitable only for trucks, vans and taxis. Possibly in the 1980s. everything was like that, but since then the situation has changed radically.
Diesel engines and fuel injection controls have become much more sophisticated. In 1985 Almost 65,000 diesel cars were sold in the UK (approximately 3.5% of total cars sold). For comparison, in 1985 Only 5,380 were sold.
(data probably for the US market).
The main parts of a diesel engine must be stronger than those of a gasoline engine.
Ignition. Sparks are not required for ignition, because the mixture ignites under compression.
Glow plugs. Heats up the combustion chamber during a cold start.
Many diesel engines are based on gasoline engines, but their main parts are more durable and can withstand high pressures.
Fuel enters the engine via a metering injection pump, which is usually attached to the side of the cylinder block. The system does not use electric ignition.
The main advantage of diesel engines over gasoline engines is reduced operating costs. Diesel engines are more efficient due to strong compression and lower fuel costs.
Of course, diesel prices can vary, so a diesel car will cost you a lot if you live in an area with high diesel prices.
In addition, such cars require maintenance less often, but oil changes are organized for them more often than for cars that run on gasoline.
Power boost
The main disadvantage of diesel engines is their low power compared to gasoline engines of equal displacement.
This problem can be solved by simply increasing the engine size, but this often leads to a significant weight of the car.
Some manufacturers equip their engines with turbochargers to make them more competitive. For example, Rover, Mercedes, Audi and VW are engaged in the production of turbodiesels.
How do diesel engines work?
Inlet
As the piston moves down the cylinder, the intake valve opens, admitting air.
Compression
When the piston reaches the bottom of the cylinder, the intake valve closes. The piston rises, compressing the air.
Ignition
Fuel is injected into the cylinder when the piston reaches the top base. This ignites the fuel and sets the piston in motion again.
Release
On the way back, the piston opens the exhaust valve and the exhaust gas exits the cylinder.
Four-stroke diesel and gasoline engines operate differently, even though they contain the same components. The main difference lies in the way the fuel is ignited and the resulting energy is managed.
In a gasoline engine, the mixture of air and fuel is ignited by a spark. In a diesel engine, the fuel is ignited by compressed air.
In diesel engines, air is compressed on average at a ratio of 1/20, while for gasoline engines this ratio is on average 1/9.
This compression greatly heats the air to a temperature sufficient to instantly ignite the fuel, so there is no need for sparks or other ignition methods when using a diesel engine.
Gasoline engines absorb a lot of air per piston stroke (the exact volume depends on the degree of opening of the throttle opening). Diesel engines always absorb the same volume, which depends on the speed, and the air duct is not equipped with a throttle. It is closed by one intake valve, and the engine does not have a carburetor or butterfly valve.
When the piston reaches the bottom of the cylinder, the intake valve opens. Under the influence of energy from the other pistons and momentum from the flywheel, the piston is sent to the upper base of the cylinder, compressing the air approximately twenty times.
Once the piston reaches the top base, a carefully measured volume of diesel fuel is injected into the combustion chamber. The heated air during compression instantly ignites the fuel, which expands during combustion and again sends the piston down, turning the crankshaft.
As the piston moves up the cylinder on the exhaust stroke, the exhaust valve opens, allowing the spent and expanded gases to exit into the exhaust pipe. At the end of the exhaust stroke, the cylinder is again ready for a new portion of fresh air.
Diesel engine design
Diesel and gasoline engines are made up of the same parts that perform the same functions. However, diesel engine parts are more durable because... they are designed to withstand heavy loads.
The walls of a diesel engine block are usually much thicker than the walls of a gasoline engine block. They are reinforced with additional bars that block impulses. In addition, the diesel engine block effectively absorbs noise.
Pistons, connecting rods, shafts and bearing housing caps are made from the most durable materials. The cylinder head of a diesel engine has a special appearance associated with the shape of the injectors, as well as the shape of the combustion chamber and swirl chamber.
Injection
For any internal combustion engine to operate smoothly and efficiently, the correct mixture of air and fuel is required. For diesel engines, this problem is especially relevant, because air and fuel are supplied at different times, mixing inside the cylinders.
Fuel injection into the engine can be direct or indirect. According to established tradition, indirect injection is more often used, because it allows you to create vortex flows that mix fuel and compressed air in the combustion chamber.
Direct injection
With direct injection, the fuel falls directly into the combustion chamber located in the piston head. This shape of the chamber does not allow mixing air with fuel and igniting the resulting mixture without the harsh knocking characteristic of diesel engines.
An indirect injection engine usually has a small spiral swirl chamber (prechamber). Before entering the combustion chamber, the fuel passes through a swirl chamber, and vortex flows are formed in it, ensuring better mixing with air.
The disadvantage of this approach is that the swirl chamber becomes part of the combustion chamber, which means that the entire structure takes on an irregular shape, causing combustion problems and negatively affecting engine efficiency.
Indirect injection
With indirect injection, fuel enters a small pre-chamber and from there into the combustion chamber. As a result, the structure takes on an irregular shape.
A direct injection engine is not equipped with a swirl chamber, and the fuel enters directly into the combustion chamber. When designing combustion chambers in the piston crown, engineers must pay special attention to their shape to ensure sufficient vortex strength.
Glow plugs
To warm up the cylinder head and cylinder block before a cold start, diesel engines use glow plugs. Short and wide spark plugs are an integral part of the car's electrical system. When the power is turned on, the elements in the candles heat up very quickly.
The spark plugs are turned on by turning the steering column specifically or using a separate switch. In the latest models, the spark plugs turn off automatically as soon as the engine warms up and accelerates above idle speed.
Speed control
Unlike gasoline engines, diesel engines have no throttle, so the amount of air they consume remains the same. The engine speed is determined only by the volume of fuel injected into the combustion chamber. The more fuel, the more energy is released during combustion.
The gas pedal is connected to a sensor in the ignition system, and not to the throttle, as in cars that run on gasoline.
To stop the diesel engine, you still need to turn the ignition key.
In a gasoline engine, the spark disappears, and in a diesel engine, the solenoid responsible for supplying fuel to the pump is turned off. After this, the engine consumes the remaining fuel and stops.
In fact, diesel engines stop faster than gasoline engines because the high pressure slows them down so much.
How to start a diesel engine
Diesel engines, like gasoline engines, start when an electric motor is turned on, which starts the compression and ignition cycle. However, at low temperatures, diesel engines have difficulty starting because the compressed air does not reach the temperature required to ignite the fuel.
To solve this problem, manufacturers make glow plugs. Glow plugs are battery-powered electric heaters that turn on a few seconds before the engine starts.
Diesel fuel
The fuel used in diesel engines is very different from gasoline. It does not undergo purification, and therefore is a viscous, heavy liquid that evaporates rather slowly.
Due to these physical properties, diesel fuel is sometimes called diesel oil or fuel oil.
In service centers and gas stations, cars running on diesel fuel are often called dervs (from diesel-engined road vehicles).
In cold weather, diesel fuel quickly thickens or even freezes. In addition, it contains a small amount of water, which can also freeze. All types of fuel absorb water from the atmosphere. Moreover, it often penetrates into underground reservoirs. The permissible water content in diesel fuel is 0.00005-0.00006%, i.e. a quarter glass of water per 40 liters of fuel.
Ice or water build-up can block fuel lines and injectors, preventing the engine from running. This is why in cold weather you can see drivers trying to heat the fuel line with a soldering iron.
As a preventative measure, you can carry an additional tank with you, but modern manufacturers already add impurities to the fuel that allow it to be used at temperatures above -12-15°C.
Source: http://17koles.ru/how/kak-rabotaet-dizelnyy-dvigatel-avtomobilya
How does a car diesel engine work?
Diesel technology has developed at an impressive pace, especially in the last ten years. Half of the new cars sold in Europe today are diesel versions.
Despite the fact that the principle of operation of the diesel engine remains the same, it has become quieter, more environmentally friendly, and the unpleasant smell, thick black smoke from the chimney and loud rattling are a thing of the past.
This is what diesel was like at the dawn of its formation
Not only efficiency, but also high power and good dynamics have become the main characteristic features of modern diesel engines. It’s interesting how a diesel engine manages to meet ever-increasing toxicity standards, not only without losing power and efficiency, but constantly improving these indicators. Let's try to consider everything in order.
How does a diesel engine work, what is good and what is not so good?
The main fundamental difference between a diesel engine and a gasoline engine is the method of preparing the working combustible mixture and its further ignition.
In most carburetor and injection gasoline engines, the working mixture is prepared in the intake tract. Although in some gasoline engines the mixture is formed, just like in a diesel engine, directly in the cylinder.
Ignition of the mixture in a gasoline engine occurs at the right moment from electrical breakdown (spark), and in a diesel engine from the high temperature of the air in the cylinder.
This is what a fire in a diesel engine looks like
A diesel engine works like this: when the piston strokes down, clean air is sucked into the cylinder, which heats up when the piston strokes up. In this case, the operating temperature of a diesel engine reaches 700-900°C, which is caused by a high compression ratio.
When the piston approaches top dead center, diesel fuel is injected into the combustion chamber under high pressure and, in contact with heated air, self-ignites.
Self-igniting diesel fuel, expanding, leads to a sharp increase in pressure in the cylinder, which, in principle, causes the increased noise of the diesel engine.
The operating principle described above allows the diesel engine to use a very lean mixture with relatively cheap diesel fuel, and this in turn determines its high efficiency and unpretentiousness.
Diesel has 10% higher efficiency and more torque than a gasoline engine.
The main disadvantages of diesel engines are increased noise and vibration, difficulties in cold starting and, of course, less power per unit volume, although modern models have practically no these disadvantages.
Features and design of some components
Considering that the compression ratio of a diesel engine is approximately 2 times higher than the compression ratio of a gasoline engine, its similar parts are significantly strengthened, since they will have to withstand higher loads.
A characteristic part of a diesel engine is its piston, the shape of the bottom of which depends on the combustion chamber, or rather on its type, and in many cases the combustion chamber itself is located in the bottom of the same piston. Unlike gasoline engines, the piston bottoms of a diesel engine, at top dead center, protrude beyond the upper plane of the cylinder block.
Since the working mixture self-ignites from compression, a diesel engine does not have a conventional ignition system, although spark plugs are also used on diesel engines.
Glow plug in a diesel engine
And these are spark plugs with a built-in glow coil, which are designed to heat the air in the combustion chamber, especially before a cold start of the engine. The main indicators of a diesel engine, both technical and environmental, are determined mainly by the fuel injection system and the type of combustion chamber.
The principle of operation of combustion chambers and their types
In diesel engines, combustion chambers can be of two types: undivided and separated. Until recently, diesel engines with separate combustion chambers predominated in passenger engineering.
In this case, the fuel was injected not into the space above the piston, but into the combustion chamber located in the cylinder head.
Separate combustion chambers, depending on the process of formation of the mixture, pre-chamber (pre-chamber) or vortex chamber, are structurally designed differently.
During the prechamber process, fuel is injected into a preliminary chamber, which communicates with the cylinder through small holes or channels; the fuel, hitting its walls, mixes with air.
The ignited mixture at high speed through channels whose cross-sections are selected so that during compression and rarefaction a large pressure difference arises between the preliminary chamber and the cylinder, enters the main chamber, where it burns completely.
In the vortex chamber process, combustion of the mixture also begins in a separate chamber, which is a hollow sphere. During the compression stroke, air enters this chamber through the connecting channel and, spinning in it, forms a vortex, due to which the fuel injected at the right time is thoroughly mixed with the air.
As you can see, in a divided chamber, the operation scheme of a diesel engine is as follows: the fuel burns in two stages, which, of course, reduces the load on the pistons, thereby ensuring smoother operation of the engine.
One of the disadvantages of diesel engines made with a divided combustion chamber is increased fuel consumption due to losses occurring due to the large surface of such a chamber, as well as significant losses due to the flow of air from the cylinder into the additional chamber and then the combustible mixture back into the cylinder. These losses also worsen the starting characteristics of the diesel engine.
Types of diesel engine chambers
Well, now about diesel engines with an undivided combustion chamber or, as they are also called, diesel engines with direct injection. In such an engine, the combustion chamber is a cavity of a certain shape, structurally made in the bottom of the piston, and fuel is injected directly into the cylinder.
Not so long ago, direct injection was the prerogative of low-speed, large-displacement diesel engines installed in trucks.
The efficiency of diesel engines with direct injection was very attractive, but their use on small-displacement diesel engines was hampered by design difficulties in organizing, strictly speaking, the combustion process and, in addition, by increased vibration and noise that appeared during acceleration.
The use of electronic fuel dosing control systems that have appeared recently has made it possible to optimize the combustion of the working mixture in diesel engines with direct injection (with an undivided combustion chamber), which in turn has led to a reduction in vibration and noise. Today, new diesel engines being developed use direct injection of diesel fuel in their design.
Fuel supply systems
The fuel supply system, being one of the most important parts of a diesel engine, is designed to provide it with the required amount of fuel at the right time, and at a given pressure.
An important element of the fuel supply system is the high-pressure fuel pump (HFP), which in the required sequence pumps the required quantities of diesel fuel supplied from the booster pump from the tank into the lines of the hydromechanical injectors of each cylinder. When there is high pressure in front of the nozzle, it opens, and when it is absent or decreases, it closes.
High pressure fuel pump
There are two types of high-pressure fuel pumps: in-line multi-plunger pumps and distributor-type pumps. An in-line pump is a set of separate sections, arranged in one row according to the number of cylinders, hence the name.
The section consists of a sleeve and a plunger included in it, driven by a shaft with cams, which receives rotation from the engine.
Despite the different principles of operation of diesel engines in modern cars, such pumps are now practically not used, because the pressure they create is not constant due to the dependence on the crankshaft speed and also because they cannot meet modern noise and environmental requirements.
Unlike in-line pumps, distribution pumps are capable of creating higher pressure during fuel injection and thereby ensuring the achievement of exhaust gas toxicity values regulated by current standards.
Such pumps create pressure with parameters corresponding to the operating mode of the engine.
The distribution pump has a distributor plunger in its design that performs rotational and translational movements; during translational movement, fuel is pumped, and during rotational movement, it is distributed among the nozzles.
These pumps are compact, provide uniform supply and distribution of fuel among the cylinders, and also work well at high speeds. Distribution pumps are very sensitive to the purity and quality of diesel fuel, since all the precision parts of such pumps are lubricated with it, and the gaps between them are very small.
For fuel injection, a pump injector is also used, installed in the engine block head on each cylinder, and is driven by the camshaft cam through a pusher. In this case, the operation cycles of a diesel engine occur alternately.
The fuel lines to the pump injector are made in the cylinder head in the form of channels, and therefore a pressure of about 2200 bar develops.
The dosage of fuel compressed to such an extent and the control of the injection advance angle are carried out using a special electronic unit that issues control commands to the electromagnetic or piezoelectric shut-off valves of the pump injectors.
Components of a pump injector
The ability of these devices to operate in pulse mode allows for preliminary injection, supplying a small portion of fuel at first, which in turn makes the engine run smoother and reduces exhaust toxicity. The main disadvantage of such injectors is the dependence of pressure on diesel engine speed and, of course, their very high cost due to complex manufacturing technology.
Turbocharging, turbodiesel
Turbocharging is an effective way to increase diesel power. With its help, you can fill the cylinders with an additional amount of working mixture, thereby increasing engine power.
The presence of one and a half to two times increased pressure of the exhaust gases of a diesel engine compared to a gasoline engine allows the turbocharger to provide turbocharging from very low speeds, and avoid the failure so typical of gasoline engines.
Since a diesel engine does not have a throttle valve, complex systems for controlling the turbocharger are not required to effectively fill the cylinders in different modes. Supercharging helps to obtain the same power from a turbodiesel as a conventional diesel engine with a smaller displacement, which in turn helps reduce its weight.
Turbocharging allows you to increase engine power
Turbocharging allows you to optimize engine performance in high mountain areas, compensating for the lack of air and thereby preventing a decrease in power. The disadvantages of a turbodiesel are mainly associated with the reliable operation of the turbocharger, the service life of which is significantly less than the service life of the engine due to stringent requirements for the quality of engine oil.
A breakdown of the turbocharger can also derail the engine itself. It should be said that the resource life of a turbodiesel is still lower than that of a conventional diesel engine, mainly due to the high degree of boost.
These turbocharged diesel engines typically have a high temperature of the gases in the combustion chamber, and to ensure reliable operation of the pistons, they are cooled by oil, which is supplied through special nozzles from below.
Video - the principle of operation of a diesel engine
There are two main tasks: reducing toxicity and increasing power; to solve them, a search is underway for new principles of operation of a diesel engine for cars. Taking this into account, in particular, modern passenger cars are equipped with turbocharged diesel engines.
Source: http://AvtoMotoSpec.ru/poleznoe/princip-raboty-dizelnogo-dvigatelya.html
The principle of operation of a diesel engine - parts and their purpose + video
The principle of operation of a diesel engine looks like self-ignition of the supplied atomized fuel when interacting with air heated during compression. In a nutshell, it is not entirely clear what we are talking about, so we will devote this article entirely to the diesel engine.
Diesel engine structure - main parts
Such engines have both a number of advantages and a number of disadvantages. The first include: the principle of its operation is ideal for heavy trucks; it is more economical compared to a gasoline power unit.
Disadvantages: the process of fuel combustion itself is tantamount to an explosion, which in itself cannot be an advantage; the fuel equipment has a rather complex design, so if it fails, you will have to tinker a lot; the developed speed will be less than when working on gasoline engines.
The design of a diesel engine is presented as follows. It all starts with the intake valve, through which air can enter the working cylinders.
The piston creates the necessary pressure so that the incoming air is heated to the required temperature, and the crankshaft receives the force coming from the piston and converts it into torque.
This is briefly what the operation of a diesel engine looks like.
The principle of operation of a diesel engine - choosing the type of combustion chamber
There are two types of areas for fuel ignition, depending on the type of diesel unit itself.
The undivided combustion chamber is located in the piston, and in this case the fuel is injected into the space above the piston.
In this case, you can count on efficiency, since the consumption of the combustible mixture will be minimal, but the negative point will be increased noise, especially during idling.
In divided combustion chambers, fuel is supplied to a separate chamber, which is connected to the cylinder through a special channel. Excellent mixing of fuel with air is ensured, only after that it is supplied to the working space, which contributes to better combustion of the mixture. This increases the purity of emissions, engine durability and car power.
How does a diesel engine work - engine timing
The operation of a diesel engine can be two-stroke or four-stroke. In the first case, the work occurs as follows: during the working stroke, the piston moves down, while the exhaust holes in the cylinder open and exhaust gases exit it.
At the same time (sometimes a little later), the inlet windows open and air is purged. Next, the piston begins to move upward, all windows close, and the process of air compression occurs.
Before the piston reaches TDC (top dead center), fuel is sprayed out of the injector, an explosion occurs, and the whole process repeats.
It is important to know how a diesel engine works in a four-stroke circuit. In the first stroke, air is admitted, at the same time the exhaust valve is open.
The second stroke corresponds to compressing the air so that it reaches the required temperature. On the third stroke, a combustible mixture is injected into the combustion chamber, and as a result of interaction with heated air, an explosion occurs.
During the fourth stroke, exhaust gases are removed from the cylinder body.
How a diesel engine works - modern realities
The design of a modern diesel engine is equipped with computer-controlled fuel supply. This system allows for the injection of a combustible mixture into the cylinders in measured portions.
This point is very important for diesel power units, since with such a supply, the pressure arising in the combustion chamber increases smoothly without the occurrence of various kinds of “jerks”, and this contributes in the best way to the soft and silent operation of the power unit.
In addition, thanks to variable injection, fuel consumption is reduced by almost 20%, while crankshaft torque increases.
It is very important for every car enthusiast to know how a diesel engine works, as well as its development trends.
For example, turbocharging, which is so popular in the latest diesel models, also effectively improves ride quality, engine power increases without forcing the crankshaft, its speed remains the same.
Source: https://carnovato.ru/princip-raboty-ustrojstvo-dizelnogo-dvigatelja-video/
Features of a diesel engine, pros and cons
Long gone are the days when in the civilian vehicle industry the diesel engine was considered in many ways a compromise “smaller brother” of gasoline engines.
Due to the characteristics of diesel fuel, this type of internal combustion engine has a number of obvious advantages.
The strengths are so obvious that even domestic designers puzzled over the implementation of this technology.
Now Gazelle Next and UAZ Patriot have such engines. Moreover, there were attempts to install a diesel engine on the Niva. Unfortunately, production was limited to small export lots.
Positive factors have allowed the diesel engine to gain popularity in every automotive segment. We are talking about a four-stroke configuration, since the two-stroke diesel engine is not widely used.
Design
The operating principle of a diesel engine is to convert the reciprocating movements of the crank mechanism into mechanical work.
The method of preparing and igniting the fuel mixture is what distinguishes a diesel engine from a gasoline engine. In the combustion chambers of gasoline engines, a pre-prepared fuel-air mixture is ignited by a spark supplied by a spark plug.
The peculiarity of a diesel engine is that mixture formation occurs directly in the combustion chamber. The power stroke is carried out by injecting a dosed portion of fuel under enormous pressure. At the end of the compression stroke, the reaction of heated air with diesel fuel leads to ignition of the working mixture.
The 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 design disadvantages:
- ineffective cylinder purging;
- increased oil consumption during active use;
- occurrence of piston rings under high-temperature operation conditions and others.
A two-stroke diesel engine with an opposite piston arrangement has a high initial cost and is very difficult to maintain. Installation of such a unit is advisable only on sea vessels. In such conditions, due to its small dimensions, low weight and greater power at identical speeds and displacement, a two-stroke diesel engine is more preferable.
A single-cylinder internal combustion unit is widely used in households as an electric generator, an engine for walk-behind tractors and self-propelled chassis.
This type of energy production imposes certain conditions on the design of a diesel engine. It does not need a fuel pump, spark plugs, ignition coil, high-voltage wires and other components vital for the normal operation of a gasoline internal combustion engine.
The injection and supply of diesel fuel involves: a high-pressure fuel pump and injectors.
To facilitate cold starts, modern engines use glow plugs, which preheat the air in the combustion chamber.
Many vehicles have an auxiliary pump installed in the tank. The job of the low pressure fuel pump is to pump fuel from the tank to the fuel equipment.
Development ways
Innovation of the diesel engine lies in the evolution of fuel equipment. The designers' efforts are aimed at achieving precise injection timing and maximum fuel atomization.
Creating a fuel “fog” and dividing the injection process into phases made it possible to achieve greater efficiency and increased power.
The most archaic examples had a mechanical injection pump and a separate fuel line to each injector. The engine design and TA of this type were highly reliable and maintainable.
The further path of development was to complicate the fuel injection pump of a diesel engine. It introduced variable injection timing, many sensors and electronic process control. In this case, the same mechanical nozzles were used. In this type of design, the fuel injection pressure was between 100 and 200 kg/cm².
The main design difficulty lies in the nozzles. It is with their help that the torque, pressure and number of injection stages are regulated. Battery-type system injectors are very demanding on fuel quality.
Airing such a system leads to rapid failure of its main elements. The common rail diesel engine is quiet, consumes less fuel and has more power.
You have to pay for all this with fewer resources and higher repair costs.
Even more high-tech is the system using pump injectors. In a TA of this type, the nozzle combines the functions of pressurizing and atomizing fuel. The parameters of a diesel engine with pump injectors are an order of magnitude higher than analog systems. However, so are the cost of maintenance and requirements for fuel quality.
The importance of turbine equipment
Most modern diesel engines are equipped with turbines.
Due to increased exhaust gas pressure, the use of turbines paired with a diesel internal combustion engine significantly increases throttle response and reduces fuel consumption.
A turbine is far from the most reliable component of a car. They often do not travel more than 150 thousand km. This is perhaps its only drawback.
Thanks to the electronic engine control unit (ECU), chip tuning is available for the diesel engine.
Advantages and disadvantages
There are a number of factors that distinguish diesel engines:
- efficiency. An efficiency of 40% (up to 50% with the use of turbocharging) is simply an unattainable figure for its gasoline counterpart;
- power. Almost all the torque is available at the lowest revs. A turbocharged diesel engine does not have pronounced turbo lag. Such throttle response allows you to get real driving pleasure;
- reliability. The mileage of the most reliable diesel engines reaches 700 thousand km. And all this without tangible negative consequences. Due to their reliability, diesel internal combustion engines are used in special equipment and trucks;
- environmental friendliness. In the fight for environmental protection, the diesel engine is superior to gasoline engines. Less CO2 emissions and the use of exhaust gas recirculation (EGR) technology cause minimal harm.
Flaws:
- price. A package equipped with a diesel engine will cost 10% more than the same model with a gasoline unit;
- complexity and high cost of maintenance. ICE components are made of more durable materials. The complexity of the engine and fuel equipment requires high-quality materials, the latest technologies and great professionalism in their manufacture;
- poor heat transfer. A high percentage of efficiency means that during fuel combustion there is less energy loss. In other words, less heat is generated. In the winter season, operating a diesel engine for short distances will negatively affect its service life.
The considered pros and cons do not always balance each other. Therefore, the question of which engine is better will always arise. If you are going to become the owner of such a car, take into account all the features of its choice. It is your requirements for the power plant that will be the factor that will decide which is better: a gasoline or diesel engine.
Is it worth buying
New diesel cars are the type of purchase that will only bring joy. By filling your car with high-quality fuel and doing maintenance in accordance with regulatory requirements, you will 100% not regret the purchase.
But it is worth considering the fact that diesel cars are much more expensive than their gasoline counterparts. You will be able to compensate for this difference and subsequently save only when you cover a large mileage. Overpay in order to drive up to 10 thousand km per year. It's simply not practical.
The situation with used cars is a little different. Despite the fact that diesel engines have a large margin of safety, over time, complex fuel equipment requires increased attention. Prices for spare parts for diesel engines over 10 years old are truly depressing.
The cost of a fuel injection pump for a budget B class car 15 years old may shock some car enthusiasts. The choice of a car with a mileage of over 150 thousand should be taken very seriously. Before purchasing, it is better to do a comprehensive diagnosis in a specialized service. Since the low quality of domestic diesel fuel has a very detrimental effect on the service life of a diesel engine.
In this case, the reputation of the manufacturer will help you decide which engine to choose. For example, the Mercedes-Benz OM602 model is rightfully considered one of the most reliable diesel engines in the world. Buying a car with a similar power unit will be a profitable investment for many years. Many manufacturers have similar “successful” power plant models.
Myths and misconceptions
Despite the prevalence of diesel cars, there are still prejudices and misunderstandings among the people.
“It rattles, it doesn’t heat up in winter, and you can’t start it in very cold weather, it doesn’t run in summer, and if something breaks, you still need to look for a repairman who will repair everything for a lot of money,” these are the words you can sometimes hear from “experienced” people. car enthusiasts. All these are echoes of the past!
- Thanks to modern technology, only the rumble of idle speed can distinguish diesel engines from gasoline ones. When driving, when road noise increases, the difference is not noticeable.
- To improve starting and warming up in cold weather, modern cars use various auxiliary systems. Due to its growing popularity, the number of services specialized in servicing diesel engines is constantly increasing.
- There is an opinion that it is difficult to boost an internal combustion engine running on diesel. This is true if we are talking about modifications of the cylinder-piston group. At the same time, chip tuning of a diesel engine is a good way to increase its power characteristics without compromising its service life.
It is worth remembering that the operating principle of a diesel engine is entirely aimed at achieving efficiency and reliability. You should not demand sky-high dynamic performance from such internal combustion engines.
Symptoms and causes of malfunctions
- Poor starting of a diesel engine when cold, and after a long period of inactivity, means poorly functioning glow plugs, air in the system, a check valve releasing fuel pressure, poor compression, a discharged battery;
- increased noise, increased consumption and black smoke from the exhaust pipe - means clogged or worn sprayers and injectors, incorrect injection timing, dirty air filter;
- loss of diesel engine power means lack of compression, turbine failure, clogged fuel and air filters, incorrect injection timing, dirty USR valve;
- gray or white smoke from the exhaust, increased oil consumption - means a cracked cylinder head or a broken cylinder head gasket (coolant leaks out and an emulsion appears in the oil), a malfunction of the turbocharger.
Correct operation
Improper operation can destroy even the most reliable motor.
Following simple rules will help you extend the life of your diesel engine and enjoy car ownership:
- Turbocharged diesel engines are very demanding on the quality of oil and fuel. Fill only with oil that meets the requirements established for your internal combustion engine. Refuel only at proven gas stations;
- Carry out maintenance of fuel equipment and preheating systems in accordance with the standards stated by the manufacturer. In this case, you will not have problems starting the diesel engine in the cold season. Operating the unit with a malfunctioning nozzle can subsequently lead to costly repairs to the internal combustion engine;
- After active travel, the turbine needs cooling. Do not turn off the engine immediately. Let it idle for a while;
- Avoid push starting. This method of reviving the engine can cause great harm to the crank mechanism of your internal combustion engine.
Today's innovative technology and progressive marketing allow people to choose from cars that they can afford. We have to compromise and sacrifice individual parameters less and less. This trend is especially noticeable in the evolution of diesel cars.
Source: https://dvigatels.ru/uhod/dizelnyj-dvigatel.html
How does a diesel engine work?
6 July 2011
- News
- Announcements
- Articles
- Press releases
- Documentation
- Stock
This article describes the main processes associated with internal combustion of fuel, talks about the four-stroke cycle, as well as all the subsystems that make the engine work.
- Introduction
- Comparison of diesel and gasoline engines
- Diesel fuel injection system
- Diesel fuel
- Improving the quality of diesel fuel and biodiesel
- To learn more
- Read also » Articles about all types of engines
This article describes the main processes associated with internal combustion of fuel, talks about the four-stroke cycle, as well as all the subsystems that make the engine work.
The history of diesel begins with the invention of the gasoline engine. In 1876 Nikolaus August Otto invented and patented the gasoline engine. His model was based on the four-stroke combustion cycle, also known as the “Otto cycle,” which is used in most modern automobile engines. At first, the gasoline engine was not very efficient, like its main competitors, such as the steam engine. In such engines, only 10% of the fuel was actually used to propel the vehicle. The rest of the fuel produced useless heat. In 1878 During classes at the Higher Polytechnic School in Germany (analogous to an engineering college), Rudolf Diesel learned about the low efficiency of gasoline and steam engines. This problem inspired him to create a more efficient engine. Many years later, in 1892. Diesel patented the “Powerful Internal Combustion Engine” of the same name. But if diesel engines are more efficient, why are gasoline engines more popular? When you think of a diesel engine, you probably think of a huge truck that spews dirty black smoke and makes a lot of noise. It is for these reasons that motorists in the United States do not like diesel. Although this type of engine is excellent for hauling goods over long distances, diesel cars are rarely purchased for everyday driving. However, progress does not stand still, and the diesel engine is being modernized to reduce air pollution and reduce noise levels. If you don’t already know, then most likely you will be interested in first learning “How a car engine works” in order to have a general understanding of the process of internal combustion of fuel. Once you've read it, come back to this page and learn all about the secrets of the diesel engine and the latest innovations. The 4.5-liter Duramax V-8 engine is 25 percent more efficient than gasoline engines while producing much cleaner emissions. Rudolf Diesel, inventor of the diesel engine. Comparison of diesel and gasoline engines By and large, diesel and gasoline engines have a similar design. Both are internal combustion engines that convert the chemical energy of fuel into mechanical energy. This mechanical energy moves the pistons up and down inside the cylinders. The pistons are connected to the crankshaft, and their linear motion is converted into a circular motion, which is necessary to rotate the wheels. Both diesel and gasoline engine types convert fuel into energy through a series of explosions or combustions. The main difference between diesel and gasoline engines is how these explosions occur. In gasoline engines, the supplied mixture of fuel and air is compressed during the stroke of the piston and ignited by a spark plug. In a diesel engine, air is first compressed, then fuel is supplied. The air heated during compression ignites the fuel. Below is an animation clearly demonstrating the diesel cycle. Compare with an animation of a gasoline engine cycle to see the main differences. A diesel engine, like a gasoline engine, uses a four-stroke combustion cycle. Four strokes of operation: Intake stroke - The intake valve opens, air is admitted and the piston moves downward. Compression Stroke – The piston moves upward, compressing the air. Power stroke - As soon as the piston reaches the top point, fuel is injected and ignited, while the piston moves down. Exhaust Stroke - The piston moves upward again, pushing combustion products out through the exhaust valve. It must be remembered that spark plugs are not used in diesel engines, because... air is injected and compressed, then fuel is injected directly into the combustion chamber (direct injection). In a diesel engine, fuel combustion occurs due to the heat of compressed air. The next section of the article introduces the diesel fuel injection process.
| Compression
Carrying out calculations, Rudolf Diesel suggested that a higher level of compression of the fuel mixture leads to increased efficiency and power. This occurs when air is compressed by a piston in a cylinder, resulting in an increase in air concentration. Diesel fuel has a high energy content, which increases the likelihood of a reaction with concentrated air. In other words, the closer the air molecules are to each other, the greater the number of oxygen molecules with which the fuel reacts. Rudolph was right - compression in a gasoline engine occurs at a ratio of 8:1 to 12:1, while compression in a diesel engine occurs at a ratio of 14:1 to 25:1. |
Diesel Fuel Injection System A significant difference between a diesel and a gasoline engine is the fuel injection process. Most car engines use port injection or carburetor injection. When injected into the intake ports, fuel enters before the start of the intake stroke (outside the cylinder). The carburetor mixes air and fuel before they enter the cylinder. Therefore, in a gasoline engine, fuel enters the cylinder during the intake stroke, then compression occurs. The compression ratio of the fuel-air mixture determines the compression of the engine - if the air is compressed too much, the fuel-air mixture will spontaneously ignite, causing detonation. This causes a sharp increase in temperature, which can lead to engine damage. Diesel engines use a direct fuel injection system - diesel fuel enters directly into the cylinder. The diesel injector is the most complex part of the engine and has undergone numerous changes. The location of the injector depends on the specific engine. The injector must withstand the high temperature and pressure inside the cylinder while spraying fuel. Evenly distributing the atomized fuel in the cylinder is also a challenge; for this, some diesel engines are equipped with intake valves, pre-combustion chambers and other devices that promote the formation of a vortex air flow to improve the combustion process. Some diesel engines use glow plugs. In a cold engine, the air compression process cannot always provide the temperature required to ignite the fuel. A glow plug is an electrically heated wire (similar to the wires used in toasters) that raises the temperature of the combustion chamber, which helps start even a cold engine. According to highly experienced heavy equipment specialist Clay Brotertor: All functions of modern diesel engines are controlled by an electronic control system, which is a bank of sensors that measure everything from engine speed, oil and coolant temperatures to the exact position of the piston (top dead center). Glow plugs are rarely used in large engines. An electronic control system monitors ambient air temperature, delaying engine starting in cold weather. In this case, fuel injection occurs later than usual. The air in the cylinder is compressed more, creating more heat, which aids starting. Small engines and engines without sophisticated electronic control systems use glow plugs to solve the problem of cold starting. It must be remembered that the mechanical design is not the only difference between a diesel engine and a gasoline engine. The fuel itself is also different.
Diesel fuel
Crude oil is a natural formation. The process of refining oil can produce several types of fuel, including gasoline, jet fuel, kerosene and, of course, diesel. If you compare gasoline and diesel fuel, you can easily find the differences. They have different smells. Diesel fuel is heavier and oilier. Diesel evaporates much more slowly than gasoline - its boiling point is much higher than that of water. Diesel resembles liquid oil. Diesel evaporation occurs more slowly because it's heavier. It contains more carbon atoms in longer chains than gasoline (gasoline's chain is C9H20, while diesel's is already C14H30). Diesel requires less refining to produce, making it cheaper than gasoline. However, since 2004 Demand for diesel fuel has increased for several reasons, including strong industrial and construction development in China and the United States [Source: US Department of Energy Energy Information Administration].
The energy density of diesel is significantly higher than that of gasoline. On average, 1 gallon (3.8 L) of diesel fuel contains 155 x 106 J (147,000 BTU), while 1 gallon of gasoline contains 123 x 106 J (125,000 BTU).
The energy density and efficiency of diesel engines explain the economical fuel consumption compared to similar gasoline engines.
Diesel fuel is used in various fields of activity. Besides trucks speeding down the highway, it is also essential in boats, buses, trains, cranes, farming, emergency vehicles and power generators. Diesel is so important to the economy that without it, industry and agriculture would instantly suffer due to heavy investment in alternative fuels with low power and efficiency. About 94% of freight transport on trains, trucks and ships depends on diesel. When it comes to environmental issues, diesel fuel has its advantages and disadvantages. Among the advantages, it should be noted that diesel produces small amounts of carbon monoxide, carbon dioxide and hydrocarbons, which contribute to global warming. Disadvantages include the high amount of nitrogen compounds and soot released, which cause acid rain, smog and poor health. The next page provides information on the latest developments to eliminate the shortcomings of diesel engines. Improved Diesel Fuel Quality and Biodiesel During the oil crisis of the 1970s, car companies in Europe began promoting diesel engines for commercial vehicles as an alternative to gasoline engines. Those who tried to switch to diesel engines were disappointed - the engines were very loud, and drivers returned home to find their cars completely covered in soot, which caused smog in large cities. However, over the last 30-40 years there have been significant improvements in engine performance and fuel cleanliness. Direct fuel injection is controlled by sophisticated computers, which increases engine efficiency and reduces harmful emissions. Highly refined diesel, such as ultra-low sulfur fuel, can reduce harmful emissions and become a cleaner fuel. Other technologies include a continuously regenerating particulate eliminator that uses filters and a catalytic converter. Soot is burned and carbon monoxide and hydrocarbon emissions are reduced by up to 90% [Source: Diesel Technology Forum]. Thanks to constantly tightening environmental fuel standards, the European Union is pushing the automotive industry to address the issue of reducing emissions. Most likely, everyone has heard of biodiesel. Is it different from a regular diesel? Biodiesel is an alternative fuel or additive for diesel engines, the use of which does not require significant changes to the engine design. Biodiesel is not a petroleum product; it is obtained from vegetable oils or animal fats after chemical modification. (Interesting fact: Rudolf Diesel originally planned to use vegetable seed oil as a fuel for his invention.) Biodiesel is added to regular diesel or used as a separate fuel.
Source: https://www.exist.ru/Document/Articles/1290
Loading...
