IN modern cars petrol mobiles power plants The principle of operation of the power system is similar to that used on diesel engines. In these engines it is divided into two - intake and injection. The first provides air supply, and the second - fuel. But due to constructive and operational features the functioning of injection differs significantly from that used on diesel engines.

Note that the difference in the injection systems of diesel and gasoline engines is increasingly erased. For getting best qualities designers borrow design solutions and apply them to different types of power systems.

Design and principle of operation of the injection injection system

The second name for injection systems in gasoline engines is injection. Its main feature is the precise dosage of fuel. This is achieved by using nozzles in the design. Device injection injection The engine includes two components - executive and control.

The task of the executive part is to supply gasoline and spray it. It does not include many components:

1. Pump (electric).
2. Filter element (fine filter).
3. Fuel lines.
4. Ramp.
5. Injectors.

But these are only the main components. The executive component may include a number of additional components and parts - a pressure regulator, a system for draining excess gasoline, an adsorber.

The task of these elements is to prepare the fuel and ensure its flow to the injectors, which are used to inject them.

The operating principle of the executive component is simple. When you turn the ignition key (on some models - when opening driver's door) the electric pump turns on, pumping gasoline and filling the remaining elements with it. The fuel is cleaned and flows through fuel lines into a ramp that connects the injectors. Due to the pump, the fuel in the entire system is under pressure. But its value is lower than on diesel engines.

The opening of the injectors is carried out due to electrical impulses supplied from the control part. This component of the fuel injection system consists of a control unit and a whole set of tracking devices - sensors.

These sensors monitor indicators and operating parameters - crankshaft rotation speed, amount of air supplied, coolant temperature, throttle position. The readings are sent to the control unit (ECU). He compares this information with the data stored in memory, on the basis of which the length of the electrical pulses supplied to the injectors is determined.

The electronics used in the control part of the fuel injection system are needed to calculate the time for which the injector should open in a particular operating mode power unit.

Types of injectors

But note that this general design gasoline engine supply systems. But several injectors have been developed, and each of them has its own design and operating features.

Engine injection systems are used on cars:

• central;
• distributed;
• direct.

Central injection is considered the first injector. Its peculiarity is the use of only one injector, which injected gasoline into the intake manifold simultaneously for all cylinders. Initially, it was mechanical and no electronics were used in the design. If we consider the design of a mechanical injector, it is similar to a carburetor system, with the only difference being that instead of a carburetor, a mechanically driven nozzle was used. Over time, the central feed was made electronic.

Now this type is not used due to a number of disadvantages, the main of which is the uneven distribution of fuel among the cylinders.

Distributed injection is currently the most common system. The design of this type of injector is described above. Its peculiarity is that each cylinder has its own fuel injector.

In this type of design, nozzles are installed in intake manifold and are located next to the cylinder head. The distribution of fuel among the cylinders makes it possible to ensure an accurate dosage of gasoline.

Direct injection is now the most advanced type of gasoline supply. In the previous two types, gasoline was supplied to the passing air stream, and mixture formation began to take place in the intake manifold. The design of the same injector copies the diesel injection system.

In a direct feed injector, the nozzle nozzles are located in the combustion chamber. As a result, the components of the air-fuel mixture are launched into the cylinders separately, and they are mixed in the chamber itself.

The peculiarity of this injector is that high fuel pressure is required to inject gasoline. And its creation is ensured by one more unit added to the device of the executive part - the pump high pressure.

Diesel engine power systems

And diesel systems are being modernized. If earlier it was mechanical, now diesel engines are equipped with electronic control. It uses the same sensors and control unit as a gasoline engine.

There are currently three types of diesel injections used on cars:

1. With distribution injection pump.
2. Common Rail.
3. Pump injectors.

As in gasoline engines, the design diesel injection consists of executive and management parts.

Many elements of the executive part are the same as those of the injectors - tank, fuel lines, filter elements. But there are also components that are not found on gasoline engines - a fuel priming pump, injection pump, lines for transporting fuel under high pressure.

IN mechanical systems For diesel engines, in-line injection pumps were used, in which the fuel pressure for each injector was created by its own separate plunger pair. Such pumps were highly reliable, but were bulky. The injection timing and the amount of diesel fuel injected were regulated by a pump.

In engines equipped with a distribution injection pump, the pump design uses only one plunger pair, which pumps fuel to the injectors. This unit is compact in size, but its service life is lower than that of in-line units. This system is used only on passenger vehicles.

Common Rail is considered one of the most efficient diesel systems engine injection. General concept it is largely borrowed from the injector with separate feed.

In such a diesel engine, the moment of start of supply and the amount of fuel is “managed” by the electronic component. The task of the high pressure pump is only to pump diesel fuel and create high pressure. Moreover, diesel fuel is not supplied directly to the injectors, but into a ramp connecting the injectors.

Pump injectors are another type of diesel injection. In this design, there is no fuel injection pump, and the plunger pairs that create diesel fuel pressure are included in the injector device. This design solution allows you to create the highest fuel pressure values ​​among existing varieties injection on diesel units.

Finally, we note that information on types of engine injection is provided here in general. To understand the design and features of these types, they are considered separately.

Video: Fuel injection system control

Sometimes called center injection, it became widely used in passenger cars in the 1980s. Similar system The fuel supply got its name due to the fact that fuel was supplied to the intake manifold at only one point.

Many systems of that time were purely mechanical, electronic control they didn't have. Often, the basis for such a power system was a conventional carburetor, from which all “extra” elements were simply removed and one or two nozzles were installed in the area of ​​its diffuser (therefore, central injection was relatively inexpensive). For example, this is how the TBI (“Throttle Body Injection”) system from General Motors was designed.

But, despite its apparent simplicity, central injection has a very important advantage over a carburetor - it more accurately doses the combustible mixture in all engine operating modes. This allows you to avoid failures in the operation of the motor, and also increases its power and efficiency.

Over time, the advent of electronic control units made central injection more compact and reliable. It has become easier to adapt it to work on different engines.

However, single-point injection also inherited from carburetors whole line shortcomings. For example, high resistance to air entering the intake manifold and poor distribution fuel mixture for individual cylinders. As a result, an engine with such a power system does not have much high performance. Therefore, today central injection is practically not found.

By the way, the General Motors concern has also developed an interesting variety central injection- CPI (“Central Port Injection”). In such a system, one nozzle sprayed fuel into special tubes that were led into the intake manifold of each cylinder. This was a kind of prototype of distributed injection. However, due to low reliability, the use of CPI was quickly abandoned.

Distributed

OR MULTI-POINT fuel injection is the most common engine power supply system on modern cars today. It differs from the previous type primarily in that there is an individual nozzle in the intake manifold of each cylinder. At certain points in time, it injects the required portion of gasoline directly into the intake valves of “its” cylinder.

Multipoint injection can be parallel or sequential. In the first case, at a certain point in time, all the injectors fire, the fuel is mixed with air, and the resulting mixture waits for the intake valves to open to enter the cylinder. In the second case, the operating period of each injector is calculated individually so that gasoline is supplied for a strictly defined time before the valve opens. The efficiency of such injection is higher, so sequential systems have become more widespread, despite the more complex and expensive electronic “stuffing”. Although sometimes there are cheaper ones combined schemes(in this case, the injectors fire in pairs).

At first, distributed injection systems were also controlled mechanically. But over time, electronics prevailed here too. After all, by receiving and processing signals from many sensors, the control unit not only commands actuators, but can also signal the driver about a malfunction. Moreover, even in the event of a breakdown, the electronics switches to emergency mode, allowing the car to independently reach a service station.

Distributed injection has a number of advantages. In addition to preparing the combustible mixture of the correct composition for each engine operating mode, such a system also more accurately distributes it among the cylinders and creates minimal resistance to the air passing through the intake manifold. This allows you to improve many engine indicators: power, efficiency, environmental friendliness, etc. Among the disadvantages of multipoint injection, perhaps only the rather high cost can be mentioned.

Direct..

The Goliath GP700 was the first production car to feature fuel injection.

INJECTION (also sometimes called direct) differs from previous types of power systems in that in this case the injectors supply fuel directly to the cylinders (bypassing the intake manifold), like diesel engine.

In principle, this power system design is not new. Back in the first half of the last century it was used on aircraft engines(for example, on the Soviet La-7 fighter). On passenger cars direct injection appeared a little later - in the 50s of the twentieth century, first on the Goliath GP700 car, and then on the famous Mercedes-Benz 300SL. However, after some time, automakers practically abandoned the use of direct injection; it remained only on racing cars.

The fact is that the cylinder head of a direct injection engine turned out to be very complex and expensive to manufacture. In addition, for a long time the designers were unable to achieve stable operation of the system. Indeed, for effective mixture formation during direct injection, it is necessary that the fuel is well atomized. That is, it was supplied to the cylinders under high pressure. And this required special pumps capable of providing it. As a result, at first, engines with such a power system turned out to be expensive and uneconomical.

However, with the development of technology, all these problems were solved, and many automakers returned to the long-forgotten scheme. The first was Mitsubishi, which in 1996 installed an engine with direct fuel injection (brand designation - GDI) on the Galant model, then other companies began to use similar solutions. In particular, “Volkswagen” and “Audi” (FSI system), “Peugeot-Citroen” (HPA), “ Alfa Romeo” (JTS) and others.

Why did such a power system suddenly interest leading automakers? It's all very simple - engines with direct injection are able to operate on a very lean working mixture (with a small amount of fuel and a large amount of air), so they are characterized by good efficiency. In addition, supplying gasoline directly to the cylinders allows you to increase the compression ratio of the engine, and therefore its power.

The direct injection power system can operate in different modes. For example, when uniform motion car at a speed of 90-120 km/h, the electronics supply very little fuel to the cylinders. In principle, such an ultra-lean working mixture is very difficult to set on fire. Therefore, direct injection engines use pistons with a special recess. It directs the bulk of the fuel closer to the spark plug, where conditions for ignition of the mixture are better.

When driving at high speeds or during sudden acceleration, significantly more fuel is supplied to the cylinders. Accordingly, due to the strong heating of engine parts, the risk of detonation increases. To avoid this, the injector injects fuel into the cylinder with a wide spray, which fills the entire volume of the combustion chamber and cools it.

If the driver requires sharp acceleration, the injector fires twice. First, at the beginning of the intake stroke, a small amount of fuel is sprayed to cool the cylinder, and then at the end of the compression stroke, the main charge of gasoline is injected.

But, despite all their advantages, engines with direct injection are not yet widespread enough. Reason - high price and demands on fuel quality. In addition, a motor with such a power system runs louder than usual and vibrates more strongly, so designers have to further strengthen some engine parts and improve sound insulation engine compartment.

Author Edition Klaxon No. 4 2008 Photo photo from the Klaxon archive

Internal combustion (ICE) is based on the combustion of a small amount of fuel in a limited volume. In this case, the released energy is converted due to the movement of the pistons into mechanical energy. A metered amount of fuel is provided by a carburetor or a special device - an injector. Engines with such devices are called injection engines. The operating principle of an injection engine is simple - supply to right moment time, the right amount of fuel to the right place.

How does an internal combustion engine work?

To clearly understand the difference between the two types power devices, it is necessary to first touch on how the internal combustion engine generally works. There are several different types, of which the most common are:

1. gasoline;
2. diesel;
3. gas-diesel;
4. gas;
5. rotary.

The principle of operation of the motor can best be understood using an example. gasoline engine. The most popular of them is the four-stroke. This means that the entire cycle of converting the energy generated during fuel combustion into mechanical energy is carried out in four cycles.
The design of the engine is such that the sequence of strokes is as follows:

• intake – filling the cylinders with fuel:
• compression – preparing fuel for combustion;
• power stroke – conversion of combustion energy into mechanical energy;
• release - removal of fuel combustion products.

To ensure engine operation, each of them has its own task. During the first stroke, the piston moves down from top position to the lowest one, the valve (intake) opens and the cylinder begins to fill with the fuel-air mixture. In the second stroke, the valves are closed, and the piston moves from the lower to the upper position, the mixture in the cylinder is compressed. When it reaches the top position, a spark jumps from the spark plug and ignites the mixture.

When it burns, increased pressure is generated, which forces the piston to move from the upper position to the lower. After reaching it, under the influence of the inertia of rotation of the crankshaft, the piston begins to move upward again, and the exhaust valve is activated, the products of fuel combustion are discharged out of the cylinder. When the piston reaches the top position, the exhaust valve closes, but the intake valve opens and the entire operating cycle is repeated.

Everything described above can be seen in the video

About the carburetor, its advantages and disadvantages

A small addition needs to be made here. Since we are considering a gasoline engine, the supply of gasoline to the engine cylinders is possible in various ways. Historically, the supply and dosage of gasoline using a carburetor was the first to be developed. This is a special device that provides the required amount fuel-air mixture(FA) in cylinders.


Fuel-air is a mixture of air and gasoline vapor. It is prepared in the carburetor, special device, to mix them in the required proportion, depending on the operating mode of the engine. Being quite simple in design, the carburetor worked successfully with a gasoline engine for a long time.
However, as the car developed, shortcomings emerged that, under the prevailing conditions by that time, were already difficult for engine developers to accept. First of all, this concerned:

• fuel efficiency. The carburetor did not provide economical consumption of gasoline when the vehicle’s driving mode suddenly changed;
• environmental safety. The content of toxic substances in the exhaust gases was quite high;
• insufficient engine power due to the fuel assemblies not matching the vehicle’s driving mode and its current condition.

To get rid of the noted shortcomings, a different principle of supplying fuel to the engine was implemented - using an injector.

About injection engines

They have another name - injection engines, which, in general, in no way changes the essence of the phenomena occurring. In terms of the work performed, injection resembles the principle implemented in the operation of a diesel engine. A strictly dosed amount of fuel is injected into the engine at the right moment through the injector nozzles, and it is ignited by a spark from a spark plug, although a spark plug is not used when the diesel engine is running.


The entire cycle of a four-stroke internal combustion engine, discussed earlier, remains unchanged. The main difference is that the carburetor prepares the fuel assembly outside the engine, and it then enters the cylinders, while in an injection engine latest models gasoline is injected directly into the cylinder.

How this happens can be seen in detail in the video.

Such a motor design allows you to solve the problems that arise during the operation of the carburetor. The use of an injector provides the following advantages to the engine compared to the carburetor option:

• increase in power by 7-10%;
• improved fuel efficiency;
• reducing the level of toxic substances in the composition exhaust gases;
• ensuring the optimal amount of fuel, depending on the driving mode of the vehicle.

These are just the main advantages that an injection engine allows you to get. However, every advantage also has its disadvantages. If a carburetor engine is purely mechanical and can be repaired in almost any conditions, then controlling an injection engine requires complex electronics and a whole system of sensors, which is why work (routine and repair) must be carried out in a service center.

Injection device

If you look at what an internal combustion engine looks like with injection instead of a carburetor, you can highlight:

• injection controller – electronic device, containing a program for the operation of all components of the system;
• injectors. There may be several or one, depending on the injection system used;
• an air flow sensor that determines the filling of the cylinders depending on the stroke. First, the total consumption is determined, and then the required amount for each cylinder is recalculated programmatically;
• sensor throttle valve(its position), establishing the current state of movement and load on the engine;
• a temperature sensor that controls the degree of heating of the coolant; according to its data, engine operation is adjusted and, if necessary, the blower fan starts operating;
• a sensor for the actual location of the crankshaft, which ensures synchronization of the operation of all components of the system;
• oxygen sensor that determines its content in exhaust gases;
• a knock sensor monitors the occurrence of the latter; to eliminate it, the ignition timing value changes according to its signals.

This is roughly what the system that provides fuel injection looks like in general terms; the principle of operation should be quite clear from its composition and the purpose of individual elements.

Types of injection systems

Despite the fairly simple description of the operation of an injection engine given earlier, there are several varieties that implement a similar principle of operation.

Single point injection

This is the simplest version of the injection principle. It is practically compatible with any carburetor engine, the difference being the use of injection instead of a carburetor. If the carburetor supplies fuel assemblies to the intake manifold, then with single-point injection gasoline is injected into the intake manifold through an injector.

As is the case with carburetor engine, during the intake stroke, the engine sucks in the finished fuel-air mixture, and its operation is practically no different from the operation of a conventional engine. The advantage of such a motor will be better efficiency.

Multipoint injection

Represents a further stage in the improvement of injection engines. According to signals from the controller, fuel is supplied to each cylinder, but also to the intake manifold, i.e. The fuel assembly is prepared outside the cylinder and enters the cylinder in finished form.
In this embodiment of the injection engine principle, it is possible to provide many of the advantages inherent in the injection engine and noted earlier.

Direct injection

It is the next stage in the development of injection engines. Fuel injection is carried out directly into the combustion chamber, which ensures the best efficiency internal combustion engine operation. The result of this approach is to obtain maximum power, minimum fuel consumption and best performance environmental safety.

The injection internal combustion engine is the next stage in the development of a gasoline engine, significantly improving its performance.

In engines using a fuel injection system, power increases, as well as the economic efficiency of their operation; they have a significantly less negative impact on the environment. 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 cylinders of the internal combustion engine. What types of SPT are there and what are their differences? 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. The main elements of fuel systems, regardless of whether they are gasoline or diesel the engines are running

1. speech:
2. 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 the fuel from dirt.
3. A mixture formation unit designed to form a combustible mixture, as well as its further transfer to the cylinders, in accordance with the operating cycle of the power unit.
4. Control module. It is used in injection engines, this is due to the need to control various sensors, valves and injectors.
5. The pump itself. As a rule, modern cars use submersible options. Such a pump is a small-sized and powerful electric motor connected to a liquid pump. The device is lubricated using fuel. If there is less than five liters of fuel in the gas tank, this can lead to engine damage.

SPT on motor ZMZ-40911.10

Features of fuel equipment

To ensure that exhaust gases pollute the environment less, cars are equipped with catalytic converters. But over time, it became clear that their use is advisable 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, car 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 the oxygen sensor, a control unit is used, this gives pretty good performance.

What are the advantages of such systems:

1. Possibility of increase performance characteristics power unit. At proper operation engine power may be higher than 5% declared by the manufacturer.
2. Improvement dynamic characteristics auto. Injection engines are quite sensitive to changes in loads, so they can independently adjust the composition of the combustible mixture.
3. Educated in correct proportions the combustible mixture can significantly reduce the volume and toxicity of exhaust gases.
4. Injection engines, as practice has shown, start perfectly in any 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 design

Now we suggest that you familiarize yourself with the design of the injection SPT. All modern power units are equipped with injectors, 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 a pumping device. The volume of incoming fuel depends on how long the injector is open, and this, in turn, is controlled by the control module.

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

1. Flow meter or mass flow sensor. Its purpose is to determine whether the engine cylinder is filled 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.
2. TPS - throttle position. Its purpose is to reflect the load on the engine, which is determined by the position of the throttle valve, engine speed, as well as cyclic filling.
3. DTOZH. The antifreeze temperature controller in the system allows you to control the fan, as well as adjust the fuel supply and ignition. Of course, all this is corrected by the control unit based on the DTOZ readings.
4. DPKV - crankshaft position. Its purpose is to synchronize the operation of the SPT as a whole. The device calculates not only the speed of the power unit, but also the position of the shaft at a certain moment. The device itself belongs to polar controllers; accordingly, its failure will lead to the impossibility of operating the car.
5. Lambda probe or oxygen sensor. It is used to determine the amount of oxygen in exhaust gases. Data from this device is sent to the control module, which, based on it, adjusts the combustible mixture (author of the video - Avto-Blogger.ru).

Types of injection systems on gasoline internal combustion engines

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

We suggest that you familiarize yourself with the issue of varieties in more detail:

1. SPT with central injection. In this case, gasoline is supplied through injectors located in the intake manifold. Since only one nozzle is used, such SPTs are also called self-injections. 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 operation, as well as high reliability. As for the minuses, this is the reduced environmental friendliness of the engine, as well as quite high fuel consumption.
2. SPT with distributed injection or K-Jetronic. Such units provide for the supply of gasoline separately to each cylinder, which is equipped with an injector. The combustible mixture itself is formed in the intake manifold. Today, most power units are equipped with just such SPT. Their main advantages include fairly high environmental friendliness, acceptable gasoline consumption, as well as moderate requirements in relation to the quality of gasoline consumed.
3. With direct injection. This option is considered one of the most progressive and perfect. The operating principle 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 combustion procedure of the mixture and largely increase the efficiency of the internal combustion engine and its power. And, of course, reduce the volume 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.
4. SPT with combined injection. This option is, in fact, the result of combining SPT with distributed and direct injection. As a rule, it is used to reduce the volume of toxic substances released into the atmosphere, as well as exhaust gases. Accordingly, it is used to increase the environmental performance of the motor.
5. L-Jetronic system also used in gasoline engines. This is a twin fuel injection system.

Photo gallery “Varieties of gasoline systems”

Types of injection systems for diesel internal combustion engines

Main types of SPT in diesel engines:

1. Pump injectors. Such SPTs are used for supplying, as well as further injection of the formed emulsion under high pressure using pump injectors. The main feature of such SPTs is that pump injectors perform pressure generation options, as well as direct injection. Such SPTs also have their disadvantages, in particular, we are talking about a pump equipped with a special permanent drive from camshaft power unit. This node is not switched off; accordingly, it contributes to increased wear structures in general.
2. Precisely because last drawback Most manufacturers prefer common rail or battery injection type SPT. This option is considered more advanced for many diesel units. SPT has this name as a result of the use of a fuel frame - the main structural element. The same ramp is used for all injectors. In this case, fuel is supplied to the injectors from the ramp itself; it can be called a battery high blood pressure.
   Fuel supply is carried out in three stages - preliminary, main, and additional. This distribution makes it possible to reduce noise and vibration during operation of the power unit, making its operation more efficient, in particular, we are talking about the process of combustion of the mixture. In addition, this also allows us to reduce the amount of harmful emissions into the environment.

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

power unit. In the late 60s and early 70s of the twentieth century, the problem of pollution arose environment industrial waste, a significant part of which was car exhaust gases. Until this time, the composition of engine combustion products internal combustion no one was interested. In order to maximum use

air during the combustion process and achieving the maximum possible engine power, the composition of the mixture was adjusted so that there was an excess of gasoline in it. As a result, there was absolutely no oxygen in the combustion products, but unburned fuel remained, and substances harmful to health were formed mainly during incomplete combustion. In an effort to increase power, designers installed accelerator pumps on carburetors that inject fuel into the intake manifold every time sharp pressing

on the accelerator pedal, i.e. when sudden acceleration of the vehicle is required. In this case, an excessive amount of fuel does not correspond to the amount of air entering the cylinders. In city traffic conditions, the accelerator pump is activated at almost all intersections with traffic lights, where cars must either stop or quickly move away. Incomplete combustion also occurs when the engine is running at, and especially when braking the engine. When the throttle is closed, air flows through the channels idle move carburetor with high speed, sucking in too much fuel.

Due to the significant vacuum in intake manifold little air is drawn into the cylinders, the pressure in the combustion chamber remains relatively low at the end of the compression stroke, the combustion process is excessive rich mixture passes slowly, and a lot of unburnt fuel remains in the exhaust gases. The described engine operating modes sharply increase the content of toxic compounds in combustion products.

It became obvious that in order to reduce emissions into the atmosphere harmful to human life, it is necessary to radically change the approach to the design of fuel equipment.

To reduce harmful emissions into the exhaust system, it was proposed to install a catalytic exhaust gas converter. But the catalyst works effectively only when the so-called normal fuel-air mixture is burned in the engine (air/gasoline weight ratio 14.7:1). Any deviation of the mixture composition from the specified one led to a drop in its operating efficiency and accelerated failure. Carburetor systems were no longer suitable for stable maintenance of such a working mixture ratio. The only alternative could be injection systems.

The first systems were purely mechanical with little use of electronic components. But the practice of using these systems has shown that the mixture parameters, the stability of which the developers counted on, change as the vehicle is used. This result is quite natural, taking into account the wear and contamination of system elements and the internal combustion engine itself during its service. The question arose about a system that could correct itself during operation, flexibly shifting the conditions for preparing the working mixture depending on external conditions.

The following solution was found. Injected into the injection system feedback– a sensor for oxygen content in the exhaust gases, the so-called lambda probe, was installed in the exhaust system, directly in front of the catalyst. This system was developed taking into account the presence of such a fundamental element for all subsequent systems as an electronic control unit (ECU). Based on signals from the oxygen sensor, the ECU adjusts the fuel supply to the engine, accurately maintaining the right composition mixtures.

Today, the injection (or, in Russian, injection) engine has almost completely replaced the outdated
carburetor system. The injection engine significantly improves the performance and power performance of the car
(acceleration dynamics, environmental characteristics, fuel consumption).

Injection systems Fuel supplies have the following main advantages over carburetor ones:

• precise dosing of fuel and, therefore, more economical fuel consumption.
• reduction of exhaust gas toxicity. Achieved through optimal fuel-air mixture and the use of exhaust gas parameter sensors.
• increase in engine power by approximately 7-10%. Occurs due to improved cylinder filling, optimal setting of the ignition timing corresponding to the engine operating mode.
• improvement dynamic properties car. The injection system immediately responds to any load changes, adjusting the parameters of the fuel-air mixture.
• ease of starting regardless of weather conditions.

Design and principle of operation (using the example of an electronic distributed injection system)

In modern injection engines An individual nozzle is provided for each cylinder. All injectors are connected to the fuel rail, where the fuel is under pressure, which is created by an electric fuel pump. The amount of fuel injected depends on the duration of the injector opening. The opening moment is regulated by an electronic control unit (controller) based on the data it processes from various sensors.

The mass air flow sensor is used to calculate the cyclic filling of the cylinders. Measured mass flow air, which is then recalculated by the program into cylinder cyclic filling. If a sensor fails, its readings are ignored and calculations are made using emergency tables.

The throttle position sensor is used to calculate the load factor on the engine and its change depending on the throttle valve opening angle, engine speed and cyclic filling.

The coolant temperature sensor is used to determine the temperature correction of fuel supply and ignition and to control the electric fan. If the sensor fails, its readings are ignored, the temperature is taken from the table depending on the engine operating time.

The crankshaft position sensor serves for overall system synchronization, calculating engine speed and crankshaft position at certain points in time. DPKV – polar sensor. If turned on incorrectly, the engine will not start. If the sensor fails, the system cannot operate. This is the only “vital” sensor in the system that makes it impossible for the car to move. Failures of all other sensors allow you to get to the service center on your own.

The oxygen sensor is designed to determine the oxygen concentration in the exhaust gases. The information provided by the sensor is used electronic unit controls to adjust the amount of fuel supplied. The oxygen sensor is used only in systems with a catalytic converter under Euro-2 and Euro-3 toxicity standards (in Euro-3 two oxygen sensors are used - before the catalyst and after it).

The knock sensor is used to monitor knock. When the latter is detected, the ECU turns on the detonation damping algorithm, quickly adjusting the ignition timing.

Listed here are only some of the basic sensors required for the system to operate. Sensor configurations on different vehicles depend on the injection system, toxicity standards, etc.

Based on the results of polling the sensors defined in the program, the ECU program controls actuators, which include: injectors, fuel pump, ignition module, idle speed regulator, canister valve for the gasoline vapor recovery system, cooling system fan, etc. (all again depends on the specific models)

Of all the above, perhaps not everyone knows what an adsorber is. The adsorber is an element of a closed circuit for recycling gasoline vapors. Euro-2 standards prohibit contact of the gas tank ventilation with the atmosphere; gasoline vapors must be collected (adsorbed) and, when purged, sent to the cylinders for afterburning. On engine not running gasoline vapors enter the adsorber from the tank and intake manifold, where they are absorbed. When the engine starts, the adsorber, at the command of the ECU, is purged with a flow of air sucked in by the engine, the vapors are carried away by this flow and are burned in the combustion chamber.

Types of fuel injection systems

Depending on the number of injectors and the location of the fuel supply, injection systems are divided into three types: single-point or mono-injection (one injector in the intake manifold for all cylinders), multi-point or distributed (each cylinder has its own injector that supplies fuel to the manifold) and direct ( fuel is supplied by injectors directly to the cylinders, like diesel engines).

Single point injection simpler, it is less stuffed with control electronics, but also less efficient. The control electronics allows you to read information from the sensors and immediately change the injection parameters. It is also important that they are easily adapted to single injection carburetor engines almost without design alterations or technological changes in production. Single-point injection has an advantage over a carburetor in fuel economy, environmental friendliness and relative stability and reliability of parameters. But single-point injection loses in engine throttle response. Another drawback: when using single-point injection, as when using a carburetor, up to 30% of gasoline settles on the walls of the manifold.

Single point injection systems were certainly a step forward compared to carburetor systems nutrition, but no longer meet modern requirements.

Systems are more advanced multipoint injection, in which fuel is supplied to each cylinder individually. Distributed injection is more powerful, more economical and more complex. The use of such injection increases engine power by approximately 7-10 percent. The main advantages of distributed injection:

• the ability to automatically adjust at different speeds and, accordingly, improve the filling of the cylinders, as a result, with the same maximum power, the car accelerates much faster;
• gasoline is injected nearby intake valve, which significantly reduces subsidence losses in the intake manifold and allows for more precise adjustment of the fuel supply.

As another and effective remedy in optimizing the combustion of the mixture and increasing the efficiency of a gasoline engine, it implements simple
principles. Namely: it atomizes fuel more thoroughly, mixes it with air better and manages the finished mixture more competently at different engine operating modes. As a result, engines with direct injection consume less fuel than conventional “injection” engines (especially with quiet ride at low speed); with the same displacement, they provide more intense acceleration of the car; they have cleaner exhaust; they guarantee higher liter power due to a higher compression ratio and the cooling effect of the air as the fuel evaporates in the cylinders. At the same time they need quality gasoline with a low content of sulfur and mechanical impurities to ensure normal operation of fuel equipment.

And the main discrepancy between the GOSTs currently in force in Russia and Ukraine and European standards is the increased content of sulfur, aromatic hydrocarbons and benzene. For example, the Russian-Ukrainian standard allows for the presence of 500 mg of sulfur in 1 kg of fuel, while Euro-3 - 150 mg, Euro-4 - only 50 mg, and Euro-5 - only 10 mg. Sulfur and water can activate corrosion processes on the surface of parts, and debris is a source of abrasive wear of calibrated holes in nozzles and plunger pairs of pumps. As a result of wear, the operating pressure of the pump decreases and the quality of gasoline atomization deteriorates. All this is reflected in the characteristics of engines and the uniformity of their operation.

First to use direct injection engine production car Mitsubishi company. Therefore, let’s look at the design and operating principles of direct injection using the example of a GDI engine (Gasoline Direct Injection). The GDI engine can operate in the combustion mode of an ultra-lean air-fuel mixture: the air-to-fuel mass ratio is up to 30-40:1.

The maximum possible ratio for traditional injection engines with distributed injection is 20-24:1 (it is worth recalling that the optimal, so-called stoichiometric, composition is 14.7:1) - if there is more excess air, the lean mixture simply will not ignite. On a GDI engine, atomized fuel is present in the cylinder as a cloud, concentrated around the spark plug.

Therefore, although the mixture as a whole is lean, at the spark plug it is close to the stoichiometric composition and ignites easily. At the same time, the lean mixture in the rest of the volume has a much lower tendency to detonation than the stoichiometric one. The latter circumstance allows you to increase the compression ratio, and therefore increase both power and torque. Due to the fact that when fuel is injected and evaporated into the cylinder, the air charge is cooled - the filling of the cylinders is somewhat improved, and the likelihood of detonation again decreases.

The main design differences between GDI and conventional injection:

High pressure fuel pump (HFP). A mechanical pump (similar to the injection pump of a diesel engine) develops a pressure of 50 bar (for an injection engine, the electric pump in the tank creates a pressure of about 3-3.5 bar in the line).

• High-pressure injectors with swirl atomizers create a fuel spray shape in accordance with the engine operating mode. In the power mode of operation, injection occurs in the intake mode and a conical fuel-air torch is formed. In the ultra-lean mixture operating mode, injection occurs at the end of the compression stroke and a compact air-fuel mixture is formed.
  a torch that the concave piston crown directs directly to the spark plug.
• Piston. A specially shaped recess is made in the bottom, with the help of which the fuel-air mixture is directed to the spark plug area.
• Inlet channels. The GDI engine uses vertical intake channels, which ensure the formation of the so-called. “reverse vortex”, directing air-fuel mixture to the spark plug and improving the filling of the cylinders with air (in a conventional engine, the vortex in the cylinder is twisted in the opposite direction).

GDI engine operating modes

There are three engine operating modes in total:

• Ultra-lean mixture combustion mode (fuel injection on the compression stroke).
• Power mode (injection on the intake stroke).
• Two-stage mode (injection on the intake and compression strokes) (used on European modifications).

Ultra-lean mixture combustion mode(fuel injection on the compression stroke). This mode is used under light loads: during quiet city driving and when driving outside the city at a constant speed (up to 120 km/h). The fuel is injected in a compact spray at the end of the compression stroke in the direction of the piston, reflected from it, mixed with air and evaporated, heading towards the spark plug area. Although the mixture in the main volume of the combustion chamber is extremely lean, the charge in the spark plug area is rich enough to ignite with a spark and ignite the rest of the mixture. As a result, the engine operates stably even with an overall air to fuel ratio of 40:1 in the cylinder.

Running the engine on a very lean mixture caused new problem– neutralization of exhaust gases. The fact is that in this mode, the main share is nitrogen oxides, and therefore the usual catalytic converter becomes ineffective. To solve this problem, exhaust gas recirculation (EGR-Exhaust Gas Recirculation) was used, which sharply reduces the amount of nitrogen oxides formed and an additional NO catalyst was installed.

The EGR system, by “diluting” the fuel-air mixture with exhaust gases, reduces the combustion temperature in the combustion chamber, thereby “muffling” the active formation of harmful oxides, including NOx. However, it is impossible to ensure complete and stable neutralization of NOx only through EGR, since as the load on the engine increases, the amount of bypassed exhaust gas must be reduced. Therefore, a NO catalyst was introduced into the direct injection engine.

There are two types of catalysts for reducing NOx emissions - Selective Reduction Type and
storage type (NOx Trap Type). Storage-type catalysts are more efficient, but are extremely sensitive to high-sulfur fuels, to which selective ones are less susceptible. In accordance with this, storage catalysts are installed on models for countries with low sulfur content in gasoline, and selective catalysts for the rest.

Power mode(injection on the intake stroke). The so-called “uniform mixture formation mode” is used for intensive city driving, high-speed suburban traffic and overtaking. The fuel is injected during the intake stroke with a conical jet, mixing with air and forming a homogeneous mixture, as in normal engine with distributed injection. The composition of the mixture is close to stoichiometric (14.7:1)

Two-stage mode(injection on intake and compression strokes). This mode allows you to increase engine torque when the driver, moving at low speeds, sharply presses the accelerator pedal. When the engine is running at low speeds and is suddenly supplied with a rich mixture, the likelihood of detonation increases. Therefore, injection is carried out in two stages. A small amount of fuel is injected into the cylinder during the intake stroke and cools the air in the cylinder. In this case, the cylinder is filled with an ultra-lean mixture (approximately 60:1), in which detonation processes do not occur. Then, at the end of the measure
compression, a compact jet of fuel is supplied, which brings the air-to-fuel ratio in the cylinder to a “rich” 12:1.

Why is this mode introduced only for cars for European market? Yes, because Japan is not characterized by high speeds movement and constant traffic jams, and Europe has long highways and high speeds (and therefore high engine loads).

Mitsubishi pioneered the use of direct fuel injection. Today, similar technology is used by Mercedes (CGI), BMW (HPI), Volkswagen (FSI, TFSI, TSI) and Toyota (JIS). Main principle the operation of these power systems is similar - the supply of gasoline is not intake tract, but directly into the combustion chamber and the formation of layer-by-layer or homogeneous mixture formation in various modes motor operation. But such fuel systems also have differences, sometimes quite significant. The main ones are working pressure in fuel system, location of nozzles and their design.