What a splash. Direct injection. Gasoline injection system, arrangement of fuel injection systems for gasoline engines

Dear readers and subscribers, it's nice that you continue to study the structure of cars! And now to your attention is an electronic fuel injection system, the principle of which I will try to tell in this article.

Yes, it is about those devices that have replaced the time-tested power supplies from under the hoods of cars, and we will also find out if modern gasoline and diesel engines have much in common.

Perhaps we would not have discussed this technology with you if a couple of decades ago humanity had not seriously taken care of the environment, and toxic exhaust gases from cars turned out to be one of the most serious problems.

The main drawback of cars with engines equipped with carburetors was the incomplete combustion of fuel, and to solve this problem, systems were needed that could regulate the amount of fuel supplied to the cylinders depending on the mode of operation of the engine.

Thus, injection systems or, as they are also called, injection systems, appeared on the automotive arena. In addition to improving environmental friendliness, these technologies have improved the efficiency of engines and their power characteristics, becoming a real boon for engineers.

Today, fuel injection (injection) is used not only on diesel, but also on gasoline units, which undoubtedly unites them.

They are also united by the fact that the main working element of these systems, whatever type they are, is the nozzle. But due to differences in the method of burning fuel, the designs of the injection units for these two types of engines, of course, differ. Therefore, we will consider them in turn.

Injection systems and gasoline

Electronic fuel injection system. Let's start with gasoline engines. In their case, injection solves the problem of creating air-fuel mixture, which is then ignited in the cylinder by a spark from a spark plug.

Depending on how this mixture and fuel is supplied to the cylinders, injection systems can have several varieties. The injection happens:

central injection

The main feature of the technology, located first in the list, is one single nozzle for the entire engine, which is located in intake manifold.It should be noted that this species injection system in terms of its characteristics, it does not differ much from the carburetor, therefore, today it is considered obsolete.

Distributed injection

More progressive is distributed injection. In this system, the fuel mixture is also formed in the intake manifold, but, unlike the previous one, each cylinder here boasts its own injector.

This variety allows you to experience all the advantages of injection technology, therefore it is most loved by automakers, and is actively used in modern engines.

But, as we know, there are no limits to perfection, and in pursuit of even higher efficiency, engineers have developed an electronic fuel injection system, namely the direct injection system.

Its main feature is the location of the nozzles, which, in this case, exit with their nozzles into the combustion chambers of the cylinders.

The formation of the air-fuel mixture, as you might guess, occurs directly in the cylinders, which has a beneficial effect on operating parameters engines, although this option is not as high as that of distributed injection, environmental friendliness. Another tangible drawback of this technology is the high requirements for the quality of gasoline.

Combined injection

The most advanced in terms of emissions of harmful substances is a combined system. This is, in fact, a symbiosis of direct and distributed fuel injection.

How about diesels?

Let's move on to diesel units. Their fuel system is faced with the task of supplying fuel at very high pressure, which, mixing in the cylinder with compressed air, ignites on its own.

A lot of options for solving this problem have been created - both direct injection into cylinders and with an intermediate link in the form of a preliminary chamber are used, in addition, there are various layouts of high pressure pumps (high pressure pumps), which also adds variety.

However, modern motorists prefer two types of systems that supply diesel fuel directly to the cylinders:

with pump nozzles;
injection common rail.

Pump nozzle

The pump-injector speaks for itself - it has an injector that injects fuel into the cylinder, and a high-pressure fuel pump are structurally combined into one unit. the main problem of such devices is increased wear, since the pump-injectors are connected by a permanent drive to the camshaft and are never disconnected from it.

common rail system

The Common Rail system takes a slightly different approach, making it the preferred choice. There is one common injection pump, which supplies diesel to the fuel rail, which distributes fuel to the cylinder nozzles.

This was just a brief overview of injection systems, so, friends, follow the links in the articles, and using the Engine section, you will find all injection systems for study modern cars mobiles. And subscribe to the newsletter so as not to miss new publications, in which you will find a lot of detailed information on the systems and mechanisms of the car.

Material from the Encyclopedia of the magazine "Behind the wheel"

Scheme Volkswagen engine FSI direct injection

The first gasoline injection systems directly into engine cylinders appeared in the first half of the 20th century. and used on aircraft engines. Attempts to use direct injection in gasoline car engines were discontinued in the 40s of the twentieth century, because such engines turned out to be expensive, uneconomical and smoked heavily in modes high power. Injecting gasoline directly into the cylinders is associated with certain difficulties. Gasoline direct injection injectors operate under more difficult conditions than those installed in the intake manifold. The head of the block, in which such nozzles must be installed, is more complex and expensive. The time allotted for the carburetion process with direct injection is significantly reduced, which means that for good carburetion it is necessary to supply gasoline under high pressure.
Mitsubishi specialists managed to cope with all these difficulties, which for the first time applied a gasoline direct injection system to automotive engines. The first mass-produced Mitsubishi Galant car with a 1.8 GDI (Gasoline Direct Injection) engine appeared in 1996.
The benefits of a direct injection system are mainly fuel economy improvements, but also some power gains. The first is due to the ability of a direct injection engine to run on very lean mixtures. The increase in power is mainly due to the fact that the organization of the process of supplying fuel to the engine cylinders allows you to increase the compression ratio to 12.5 (in conventional gasoline engines, it is rarely possible to set the compression ratio above 10 due to detonation).

Nozzle GDI engine can operate in two modes, providing a powerful (a) or compact (b) torch of atomized gasoline

In the GDI engine, the fuel pump provides a pressure of 5 MPa. An electromagnetic nozzle installed in the cylinder head injects gasoline directly into the engine cylinder and can operate in two modes. Depending on the applied electrical signal, it can inject fuel either with a powerful conical torch or with a compact jet.

The piston of a gasoline direct injection engine has a special shape (combustion process above the piston)

The bottom of the piston has a special shape in the form of a spherical recess. This shape allows the incoming air to be swirled, directing the injected fuel to a spark plug mounted in the center of the combustion chamber. The inlet pipe is not located on the side, but vertically from above. It does not have sharp bends, and therefore the air enters from high speed.

In the operation of an engine with a direct injection system, three different modes can be distinguished:
1) mode of operation on super-poor mixtures;
2) operating mode on a stoichiometric mixture;
3) the mode of sharp accelerations from low speeds;
The first mode is used when the car is moving without sharp accelerations at a speed of about 100–120 km/h. This mode uses a very poor combustible mixture with an excess air ratio of more than 2.7. Under normal conditions, such a mixture cannot be ignited by a spark, so the injector injects fuel in a compact flame at the end of the compression stroke (as in a diesel engine). A spherical recess in the piston directs the jet of fuel to the spark plug electrodes, where the high concentration of gasoline vapor allows the mixture to ignite.
The second mode is used when the car is moving at high speed and when sharp accelerations when high power is needed. This mode of motion requires a stoichiometric composition of the mixture. A mixture of this composition is highly flammable, but the GDI engine has an increased compression ratio, and in order to prevent detonation, the nozzle injects fuel with a powerful torch. The finely atomized fuel fills the cylinder and evaporates to cool the cylinder surfaces, reducing the chance of knocking.
The third mode is necessary to obtain a large torque when hard pressing pedal "gas" when the engine is running at low speeds. This mode of operation of the engine is different in that the nozzle fires twice during one cycle. During the intake stroke, an extra-poor mixture (α=4.1) is injected into the cylinder to cool it with a powerful torch. At the end of the compression stroke, the injector injects fuel again, but with a compact flame. In this case, the mixture in the cylinder is enriched and detonation does not occur.
Compared with conventional engine with a gasoline port injection system, a GDI engine is about 10% more economical and emits 20% less carbon dioxide into the atmosphere. The increase in engine power is up to 10%. However, as the operation of vehicles with engines of this type has shown, they are very sensitive to the sulfur content in gasoline. The original gasoline direct injection process was developed by Orbital. In this process, gasoline is injected into the engine cylinders, pre-mixed with air using a special nozzle. The Orbital nozzle consists of two jets, fuel and air.

Orbital nozzle operation

Air is supplied to the air jets in compressed form from a special compressor at a pressure of 0.65 MPa. The fuel pressure is 0.8 MPa. First, the fuel jet fires, and then the air jet at the right time, so the fuel-air mixture in the form of an aerosol is injected into the cylinder with a powerful torch.
An injector mounted in the cylinder head next to the spark plug injects a fuel-air jet directly onto the spark plug electrodes, which ensures good spark plug ignition.

Design features of a direct injection engine Audi gasoline 2.0 FSI

The direct fuel injection system in gasoline engines is by far the most advanced and modern solution. Main Feature direct injection can be considered that the fuel is supplied to the cylinders directly.

For this reason this system also often referred to as direct fuel injection. In this article, we will look at how a direct injection engine works, as well as what advantages and disadvantages such a scheme has.

Read in this article

Direct fuel injection: direct injection system device

As mentioned above, the fuel in these is supplied directly to the combustion chamber of the engine. This means that the injectors do not spray gasoline into, after which the fuel-air mixture enters through the cylinder, but directly inject fuel into the combustion chamber.

The first direct injection gasoline engines were . In the future, the scheme became widespread, as a result of which today with such a fuel supply system can be found in the lineup of many well-known automakers.

For example, concern VAG introduced a number Audi models and Volkswagen with naturally aspirated and turbocharged ones that received direct fuel injection. Also direct injection engines BMW company, Ford, GM, Mercedes and many others.

Direct fuel injection has become so widespread due to the high efficiency of the system (about 10-15% compared to distributed injection), as well as more complete combustion of the working mixture in the cylinders and a decrease in exhaust gas toxicity.

Direct injection system: design features

So let's take as an example FSI engine with its so-called "layered" injection. The system includes the following elements:

high pressure circuit;
gasoline;
pressure regulator;
fuel rail;
high pressure sensor;
injection nozzles;

Let's start with fuel pump. The specified pump creates a high pressure under which fuel is supplied to fuel rail as well as injectors. The pump has plungers (there may be several plungers, or one in rotary pumps) and is driven by the inlet camshaft.

RTD (fuel pressure regulator) is integrated into the pump and is responsible for the metered fuel supply, which corresponds to the injector injection. A fuel rail (fuel rail) is needed in order to distribute fuel to the injectors. Also, the presence of this element allows you to avoid pressure surges (pulsations) of the fuel in the circuit.

By the way, the circuit uses a special safety valve, which is in the rail. This valve is needed in order to avoid too high fuel pressure and thus protect individual elements systems. An increase in pressure can occur due to the fact that the fuel tends to expand when heated.

The high pressure sensor is a device that measures the pressure in the fuel rail. Signals from the sensor are transmitted to, which, in turn, is able to change the pressure in the fuel rail.

As for the injection nozzle, the element ensures the timely supply and atomization of fuel in the combustion chamber in order to create the necessary fuel-air mixture. Note that the processes described are controlled by . The system has a group of different sensors, the electronic unit controls and actuators.

If we talk about the direct injection system, together with the high fuel pressure sensor, the following are involved for its operation:, DPRV, air temperature sensor in the intake manifold, coolant temperature sensor, etc.

Thanks to the operation of these sensors, the necessary information is supplied to the ECU, after which the unit sends signals to the actuators. This allows you to achieve coordinated and accurate work. solenoid valves, nozzles, safety valve and a number of other elements.

How Direct Fuel Injection Works

The main advantage of direct injection is the ability to achieve various types of mixture formation. In other words, such a power supply system is able to flexibly change the composition of the working fuel-air mixture, taking into account the operating mode of the engine, its temperature, the load on the internal combustion engine, etc.

It is necessary to single out layer-by-layer mixing, stoichiometric, and also homogeneous. It is this mixture formation that ultimately makes it possible to use fuel as efficiently as possible. The mixture always turns out to be of high quality, regardless of the mode. ICE operation, gasoline burns fully, the engine becomes more powerful, while exhaust toxicity is reduced at the same time.

Layered mixture formation is activated when the engine loads are low or medium, and the crankshaft speed is low. Simply put, in such modes, the mixture is somewhat leaner in order to save money. Stoichiometric mixing involves preparing a mixture that is highly flammable without being overly enriched.
Homogeneous mixture formation allows you to get the so-called "power" mixture, which is needed at high engine loads. On a lean homogeneous mixture, in order to further save money, the power unit operates in transient modes.
When stratification is engaged, the throttle is wide open with the intake flaps closed. Air is supplied to the combustion chamber at a high speed, turbulence of air flows occurs. Fuel is injected near the end of the compression stroke, injection is made in the area where the spark plug is located.

In the short time before a spark appears on the spark plug, a fuel-air mixture is formed in which the excess air ratio is 1.5-3. Next, the mixture is ignited by a spark, while a sufficient amount of air is retained around the ignition zone. This air acts as a thermal "insulator".

If we consider homogeneous stoichiometric mixture formation, such a process occurs when the intake flaps are open, while the throttle is also open at one angle or another (depending on the degree of pressing the accelerator pedal).

In this case, the fuel is injected even during the intake stroke, as a result of which it is possible to obtain a homogeneous mixture. Excess air has a coefficient close to unity. Such a mixture is highly flammable and fully burns throughout the entire volume of the combustion chamber.

A lean homogeneous mixture is created when the throttle is fully open and the intake flaps are closed. In this case, air is actively moving in the cylinder, and fuel injection falls on the intake stroke. The ECM maintains excess air at 1.5.

In addition to clean air, exhaust gases can be added. This is due to work. As a result, the exhaust “burns out” again in the cylinders without damage to the engine. At the same time, the level of emissions of harmful substances into the atmosphere is reduced.

What is the result

As you can see, direct injection allows you to achieve not only fuel economy, but also a good return on the engine in both low and medium, and high loads. In other words, the presence of direct injection means that the optimal composition of the mixture will be maintained in all modes of operation of the internal combustion engine.

As for the disadvantages, the disadvantages of direct injection can only be attributed to the increased complexity during repairs and the price of spare parts, as well as the high sensitivity of the system to fuel quality and the condition of fuel and air filters.

Brief history of appearance

The fuel injection system began to be actively introduced in the 70s, as a reaction to the increased level of pollutant emissions into the atmosphere. It was borrowed in the aircraft industry and was environmentally more safe alternative carbureted engine. The latter was equipped mechanical system fuel supply, in which fuel entered the combustion chamber due to the pressure difference.

The first injection system was almost completely mechanical and was characterized by low efficiency. The reason for this was the lack of technical progress who could not reach her full potential. The situation changed in the late 1990s with the development electronic systems engine control. The electronic control unit began to control the amount of fuel injected into the cylinders and percentage air-fuel mixture components.

Types of injection systems for gasoline engines

There are several main types of fuel injection systems, which differ in the way the air-fuel mixture is formed.

Single injection, or central injection

Scheme of operation of the mono-injection system

The central injection scheme provides for the presence of one, which is located in the intake manifold. Such injection systems can only be found on older cars. It consists of the following elements:

Pressure regulator - provides a constant working pressure of 0.1 MPa and prevents the appearance of air pockets in.
Injection nozzle - performs a pulsed supply of gasoline to the engine intake manifold.
— regulates the volume of supplied air. May be mechanical or electrically driven.
Control unit - consists of a microprocessor and a memory unit that contains the reference data of the fuel injection characteristics.
Position sensors crankshaft engine, position throttle valve, temperature, etc.

Gasoline injection systems with a single nozzle work according to the following scheme:

The engine is running.
Sensors read and transmit information about the state of the system to the control unit.
The received data is compared with the reference characteristic, and, based on this information, the control unit calculates the moment and duration of the nozzle opening.
A signal is sent to the electromagnetic coil to open the nozzle, which leads to the supply of fuel to the intake manifold, where it mixes with air.
A mixture of fuel and air is supplied to the cylinders.

Multiport Injection (MPI)

A multiport injection system consists of similar elements, but in this design there are separate nozzles for each cylinder, which can be opened simultaneously, in pairs or one at a time. The mixing of air and gasoline also occurs in the intake manifold, but, unlike mono-injection, fuel is supplied only to the intake tracts of the corresponding cylinders.

Scheme of operation of the system with distributed injection

The control is carried out by electronics (KE-Jetronic, L-Jetronic). These are universal Bosch fuel injection systems that are widely used.

The principle of operation of distributed injection:

Air is supplied to the engine.
With the help of a number of sensors, the volume of air, its temperature, the speed of rotation of the crankshaft, as well as the parameters of the throttle position are determined.
Based on the received data, the electronic control unit determines the amount of fuel that is optimal for the incoming amount of air.
A signal is given and the corresponding nozzles are opened for the required period of time.

Direct fuel injection (GDI)

The system provides for the supply of gasoline by separate nozzles directly to the combustion chambers of each cylinder under high pressure, where air is simultaneously supplied. This injection system provides the most accurate concentration of the air-fuel mixture, regardless of the engine operating mode. At the same time, the mixture burns out almost completely, thereby reducing the amount of harmful emissions into the atmosphere.

Diagram of the direct injection system

Such an injection system is complex and susceptible to fuel quality, making it expensive to manufacture and operate. Since the injectors operate in more aggressive conditions, for the correct operation of such a system, it is necessary to ensure high fuel pressure, which must be at least 5 MPa.

Structurally, the direct injection system includes:

High pressure fuel pump.
Fuel pressure control.
Fuel rail.
Safety valve (installed on the fuel rail to protect system elements from pressure increase above the permissible level).
High pressure sensor.
Nozzles.

An electronic injection system of this type from Bosch received the name MED-Motronic. The principle of its operation depends on the type of mixture formation:

Layered - implemented at low and medium engine speeds. Air is fed into the combustion chamber at high speed. Fuel is injected towards and, mixing with air along the way, ignites.
Stoichiometric. When you press the gas pedal, the throttle opens and fuel is injected simultaneously with the air supply, after which the mixture ignites and burns completely.
Homogeneous. In the cylinders, intensive air movement is provoked, while gasoline is injected on the intake stroke.

In a gasoline engine, this is the most promising direction in the evolution of injection systems. It was first implemented in 1996 on passenger cars. Mitsubishi cars Galant, and today it is installed on their cars by most of the largest automakers.

In every modern car there is a fuel supply system. Its purpose is to supply fuel from the tank to the engine, filter it, and also form a combustible mixture with its subsequent entry into the internal combustion engine cylinders. What are the types of SPT and what is their difference - we will discuss this below.

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General information

As a rule, most injection systems are similar to each other, the fundamental difference may lie in mixture formation.

Essential elements fuel systems, regardless of whether it is petrol or diesel engines is talking about:

A tank in which fuel is stored. The tank is a container equipped with a pumping device, as well as a filter element for cleaning fuel from dirt.
Fuel lines are a set of pipes and hoses designed to supply fuel from the tank to the engine.
A mixture formation unit designed to form a combustible mixture, as well as its further transfer to the cylinders, in accordance with the cycle of operation power unit.
control module. It is used in injection engines, this is due to the need to control various sensors, valves and nozzles.
The pump itself. As a rule, submersible options are used in modern cars. Such a pump is a small electric motor connected to a liquid pump. The device is lubricated with fuel. If there is less than five liters of fuel in the gas tank, this can lead to engine breakdown.

SPT on the motor ZMZ-40911.10

Features of fuel equipment

In order for exhaust gases to pollute the environment less, cars are equipped with catalytic converters. But over time, it became clear that their use is appropriate only if a high-quality combustible mixture is formed in the engine. That is, if there are deviations in the formation of the emulsion, then the efficiency of using the catalyst is significantly reduced, which is why, over time, auto manufacturers switched from carburetors to injectors. However, their effectiveness was also not particularly high.

So that the system could automatically adjust the indicators, a control module was subsequently added to it. If, in addition to the catalytic converter, as well as oxygen sensor, a control unit is used, this gives pretty good performance.

What are the advantages of such systems:

Possibility of increasing performance characteristics power unit. With proper operation, engine power can be higher than 5% declared by the manufacturer.
Improvement dynamic characteristics auto. Injection motors are quite sensitive to changes in loads, so they can independently adjust the composition of the combustible mixture.
A combustible mixture formed in the correct proportions can significantly reduce the volume, as well as the toxicity of exhaust gases.
Injection motors, as practice has shown, start perfectly in all weather conditions, unlike carburetors. Of course, if we are not talking about a temperature of -40 degrees (the author of the video is Sergey Morozov).

Fuel injection system device

Now we suggest that you familiarize yourself with the device of the injection SPT. All modern power units are equipped with nozzles, their number corresponds to the number of installed cylinders, and these parts are connected to each other using a ramp. The fuel itself is contained in them under low pressure, which is created thanks to the pumping device. The amount of incoming fuel depends on how long the nozzle is open, and this, in turn, is controlled by the control module.

To adjust, the unit receives readings from various controllers and sensors located in different parts of the car, we suggest that you familiarize yourself with the main devices:

Flow meter or DMRV. Its purpose is to determine the fullness of the engine cylinder with air. If there are problems in the system, then the control unit ignores its readings, and uses the usual data from the table to form the mixture.
TPS - throttle position. Its purpose is to reflect the load on the motor, which is due to the position of the throttle valve, engine speed, as well as cyclic filling.
DTOZH. The antifreeze temperature controller in the system allows you to implement fan control, as well as adjust the fuel supply and ignition. Of course, all this is corrected by the control unit, based on the readings of the DTOZH.
DPKV - crankshaft position. Its purpose is to synchronize the operation of the SPT as a whole. The device calculates not only the revolutions of the power unit, but also the position of the shaft at a certain moment. The device itself belongs to the polar controllers, respectively, its failure will lead to the impossibility of operating the car.
Lambda probe or . It is used to determine the amount of oxygen in the exhaust gases. The data from this device is sent to the control module, which, based on them, adjusts the combustible mixture (the author of the video is Avto-Blogger.ru).

Types of injection systems on gasoline ICEs

What is Jetronic, what types of SPT gasoline engines are there?

Let's take a closer look at the issue of varieties:

SPT with central injection. In this case, gasoline, the supply of gasoline is realized thanks to the injectors located in the intake manifold. Since there is only one injector used, these SPTs are also called mo-injectors. Currently, such SPTs are not relevant, so they are simply not provided for in more modern cars. The main advantages of such systems include ease of use, as well as high reliability. As for the minuses, this is a reduced environmental friendliness of the motor, as well as a rather high fuel consumption.
SPT with port injection or K-Jetronic. In such units, gasoline is supplied separately to each cylinder, which is equipped with a nozzle. The combustible mixture itself is formed in the intake manifold. To date, most of the power units are equipped with just such SPTs. Their main advantages include a fairly high environmental friendliness, acceptable gasoline consumption, as well as moderate requirements in relation to the quality of gasoline consumed.
With direct injection. This option is considered one of the most progressive, as well as perfect. The principle of operation of this SPT is the direct injection of gasoline into the cylinder. As the results of numerous studies show, such SPTs make it possible to achieve the most optimal and high-quality composition of the air-fuel mixture. Moreover, at any stage of the operation of the power unit, which can significantly improve the procedure for the combustion of the mixture and in many respects increase the efficiency of the internal combustion engine and its power. And, of course, reduce the amount of exhaust gases. But it must be taken into account that such SPTs also have their drawbacks, in particular, a more complex design, as well as high requirements for the quality of the gasoline used.
SPT with combined injection. This option is, in fact, the result of combining PPT with distributed and direct injection. As a rule, it is used in order to reduce the amount of toxic substances released into the atmosphere, as well as exhaust gases. Accordingly, it is used to increase the indications of the environmental friendliness of the motor.
L-Jetronic system still used in gasoline engines. This is a dual fuel injection system.

Photo gallery "Varieties of gasoline systems"

Types of injection systems for diesel internal combustion engines

The main types of SPT in diesel engines:

Injector pump. Such SPTs are used for feeding, as well as further injection of the formed emulsion under high pressure using pump nozzles. The main feature of such SPTs is that pump injectors perform pressure generation options, as well as direct injection. Such SPTs also have their drawbacks, in particular, we are talking about a pump equipped with a special constant-type drive from camshaft power unit. This node is not disconnected, respectively, it contributes to increased wear of the structure as a whole.
It is because of the latter drawback that most manufacturers prefer common rail or battery injection. This option is considered more perfect for many diesel units. SPT has such a name as a result of the use of a fuel frame - the main structural element. The ramp is used one for all nozzles. In this case, the fuel supply is carried out to the nozzles from the ramp itself, it can be called an overpressure accumulator.
Fuel supply is carried out in three stages - preliminary, main, and additional. This distribution makes it possible to reduce noise and vibration during the operation of the power unit, to make its work more efficient, in particular, we are talking about the process of ignition of the mixture. In addition, it also allows you to reduce the amount of harmful emissions into the environment.

Regardless of the type of SPT, diesel units are also controlled by electronic or mechanical devices. In mechanical versions, the devices control the level of pressure and volume of the components of the mixture and the moment of injection. With regard to electronic options, they allow for more effective management power unit.