The injection engine is a further step in the history of the development of internal combustion engines. Components of the injection engine power system and types of designs

The use of devices with a similar algorithm of action initially touched the aircraft industry. Tightening environmental standards led to the fact that many car manufacturers abandoned the use of carburetor engines, further improvement of which did not lead to the desired result.

The fuel injection system is controlled by an automated system or on-board computer. Checking the condition of the air fuel mixture and when it matches, fuel is sequentially injected directly into the intake valve. This ensures more accurate consumption, as well as rapid combustion of fuel.

Device injection engine can be characterized by the following sequence:

1. Pressing the gas pedal opens the throttle. This allows air to enter the engine.
2. The computer analyzes the volume of incoming air (depending on the force of pressing the pedal), and then gives a command to supply the optimal amount of fuel.
3. A special sensor controls the amount of oxygen entering the engine and its correspondence to the volume of fuel.
4. The fuel pump pumps the required volume, after which it is injected under pressure. As a result, a fine mist is formed, which quickly burns out, setting in motion the rotation mechanisms of the moving parts of the motor.

Even a simplified diagram shows how complex the process of driving a car is. The operation of the injector engine is a closed system in which every detail matters. If any component fails, a signal about this is sent to the electronic system, after which the computer itself decides on the possibility further movement. This is both an advantage and a disadvantage of such a mechanism, because under changed working conditions it will not work to “manually” swing the system, you will have to seek qualified help.

What are the features of the device?

As the above information shows, the main difference from older carburetor models is automatic fuel supply. This is a key point that determines the benefits of using injection device. In addition, there are a few more points that distinguish the difference between an injector and a carburetor.

Key differences:

• Due to the fact that a certain level of pressure is created in the carburetor engine, which allows the air-fuel mixture to be sucked in, and it is supplied automatically in the injector, the recoil power is saved. This allows you to generally increase the performance of the car by 10%. The indicator is small, but long-term operation that's a significant fuel savings.
• Rapid response to changing traffic conditions. In the injector almost instantly there is an increase or decrease in fuel supply. This allows you to maneuver on the road much faster.
• The fuel injection system provides easy starting of the engine.
• The injection device is less sensitive to changing weather conditions. Fuel consumption will be saved due to the fact that a long warm-up of the engine is not required.
• Also, such devices comply with more stringent modern environmental standards. Level harmful emissions, as a rule, lower by 50-70%, which in modern world just necessary.

Among the main disadvantages is the complete dependence of the system on the serviceability of all elements. The injector is equipped with several sensors that analyze fuel parameters and operating conditions. If the electronics fail, expensive repairs may be required.

Also, when operating a car with an injection engine, it is necessary to carefully monitor the condition of the fuel used. The nozzles that supply and spray the air-fuel mixture are often clogged when low-quality gasoline is used. At the same time, this criterion is very difficult to control, especially during a long trip, when you have to refuel at unverified points. The disadvantages also include expensive repairs in case of breakdowns. Self-repair of the electronic part in practice turns out to be an unsuccessful solution and may lead to the need to restore the system, and this costs a lot.

The main control center of the injector is the ECU - an electronic control unit. Its tasks include direct control over the operation of all systems, fuel consumption and supply, as well as signaling possible malfunctions in the operation of the car. Reporting possible system failures and algorithm correct operation stored in special memory cells,

Depending on the model, there are usually three types of device memory:

1. The PROM requires a one-time programming, after which all the action algorithms for controlling the system are stored. The chip is stored on the board of the block, if necessary, it must be replaced. Information cannot be deleted in case of network failures, cannot be corrected.
2. RAM is a random access memory. Refers to temporary file storage. It also serves as a place for calculating and analyzing the information received. The RAM is located on the printed circuit board of the unit; in case of network failures, the information is erased.
3. EPROM is an electrically programmable memory device. Mainly used to store information for anti-theft system(codes and passwords of the owner). If the data entry is violated, the engine will not start. Such storage does not depend on network data, information will be saved in any situation.

The damper that allows you to control the injection of fuel into the system is called a nozzle. Two types of fuel supply system are used. Mono-injection is now practically not used. With this arrangement of the nozzle, fuel is supplied regardless of the opening inlet valve engine. In addition, such control is little controlled by electronics. The second type - distribution injection is represented by a more advanced system. Thanks to several nozzles located directly next to each cylinder, there is a directed access of fuel. Such a system clearly regulates the supply of fuel, and also increases engine performance. The type of injector control is also determined by the ECU and can be point and sequential.

catalytic converter

This element of the injection engine system is designed to control car emissions. It requires an oxygen sensor to function. exhaust gases(Lambda probe). When exceeding allowed values fuel injection is adjusted, and the exhaust gas recirculation process is also carried out. In addition, the system provides special catalysts that reduce the content of harmful impurities after fuel combustion.

Sensors

A complex electronic control system involves checking and adjusting several sensors. If at least one element fails, the ECU gives an error.

The main sensors of the injection engine:

• DMRV (mass air flow sensor). Provides information about the mass of air entering the engine.
• Lambda probe (oxygen sensor). Determines the oxygen content in the air-fuel mixture. Using this information, the ECU can detect changes in the fuel mixture and correct its values.
• Throttle sensor. Controls the position of the throttle valve, according to which the control unit can respond by increasing or reducing the fuel supply as needed.
• Voltage sensor. Controls voltage onboard network cars. The sensor readings, if necessary, force the control unit to increase the idle speed if the voltage is low (most often at high electrical loads).
• Coolant temperature control sensor. It gives a signal that the engine is warming up, after which the ECU starts the work of other systems.
• Sensor absolute pressure. Monitors pressure in intake manifold. From the amount of air that enters the engine, the consumption of the fuel mixture changes. Also, this indicator is used in determining the performance of the car.
• Crankshaft rotation sensor. Rotational speed crankshaft- one of the determining factors that affect the calculation of the required pulse duration.

The advantages of the injector have already been appreciated by many motorists. Fuel consumption is reduced, vehicle performance is increased, and the process of driving is also facilitated. The operation of the injection engine is ensured by direct fuel injection into the system, based on the analyzed data on the parameters of the fuel mixture and the engine operation mode. How an injection engine works, its advantages and disadvantages compared to carburetor device discussed in our article.

Injection cars have long been replaced by carbureted cars. And although both types of vehicles are equally common on domestic roads, the principle of the device of the latter raises much more questions. This review article will explain the device of the injector, what are the advantages and features of its operation.

What is an injector

The term "injector" means a nozzle separately installed on the engine or a specific part of the vehicle's integral system that serves to distribute the fuel mixture. Fuel injection occurs either directly into the engine cylinders, or into its intake manifold. This is the main difference between injection and carburetor units.
Based on the installation location of the nozzle, there are several varieties of these devices. Any of them will provide either a point supply of the fuel mixture to the engine of the machine, or its location in the combustion chamber for further production. fuel-air mixture.

It doesn't matter what fuel your car "prefers" - this structural element equally successfully operates on both diesel and gasoline versions of vehicles.

History of occurrence

The first installation of injectors on vehicles was carried out by Bosch specialists, who installed the injection engine on the Goliaath 700 Sport coupe. This happened back in 1951, and after 3 years, representatives of the Mercedes company followed their example. These are the first successful experiences of using injectors in road transport.
There is also evidence that installations of this type were used even earlier: approximately in the 30s of the twentieth century, mainly on military aviation equipment. Of course, the first injectors could not be called ideal, since they did not cope well with the function assigned to them to increase engine power, and few people were interested in fuel economy and high environmental friendliness of cars in those days.

After jet engines began to be used in the 40s, injection engines were forgotten for a while, especially since the efficiency of the first such devices was low. Apart from the installation of injectors on Bosch and Mercedes cars, we can say that a full-fledged revival of these devices took place only in the 80s, when they began to be massively introduced into the automotive industry.
A significant role in this "resurrection" was played by the need to reduce the toxicity of gases emitted into the atmosphere, which forced the engineers to slightly modernize the old models of injectors. This they did well, since it is this type of engine that is found on most modern cars.

Did you know? The first ancestor of the modern automobile "saw" the world in 1768. It was a steam-powered machine capable of transporting people, but only vaguely resembled modern cars. The first vehicle, the movement of which was provided by the internal combustion engine and already more like a car familiar to us, was presented to the public only in 1806.

Types of injection nozzles

Today, there are two main types. injection nozzle It happens electronic And mechanical. In the first case, the fuel mixture passes directly to the injectors, and then, with the participation of the electronic control unit, it is dosed and sent to the combustion chamber. This option is more convenient for permanent operation vehicle, so they are almost always installed on new cars.
In the case of a mechanical injector, we are talking about a unit without an ECU, where the regulation of the fuel supply to the engine is carried out by means of valves (depending on the level of openness of the nozzle, the corresponding amount of the fuel mixture is also prepared). The first injectors were of this type, they are still found on older car models. On new vehicles, only electronic versions are installed.

There is a classification electronic injectors based on the fuel injection method. There are three varieties:

Device

One of the simplest parts of a complex car system is the injection system. This includes:

As for the nozzle itself, it all depends on the specific type. For example, an electromagnetic one consists of an electromagnet armature, a nozzle, a seal, a needle, an excitation winding, a spring, a strainer and an electromagnetic connector. All these details are in the general case.

Important! To ensure stable and trouble-free operation of the injector, it is worth periodically checking the cleanliness of the nozzles (especially if low-quality fuel was used to refuel the car).

In the electro-hydraulic nozzle you will not find a strainer, there, in addition to the rest of the components, there are:

In the piezoelectric nozzle, in addition to the main components, there is also a switching valve and a discharge channel that are directly involved in its operation. Despite the fact that the work of injectors different types has certain differences, the basic principle of their activity is almost the same.

Did you know? The first ECU appeared almost simultaneously with the injector itself, namely in 1939. At that time he hardly remembered modern device and was used only in the Kommandogerat aircraft engine operation system.

How does it work

If we omit minor details, then the operation of the injector will consist of stages that are closely interconnected:

1. Measurement of the mass of incoming air using a special sensor.
2. Transferring the information received to the injector ECU (it also receives data from other sensors: temperature, throttle, measuring the speed of rotation of the crankshaft).
3. Computer calculation of the required amount fuel fluid after analyzing the information from the sensors.
4. Impact electrical discharge of a set duration on the injectors, which contributes to their opening and transfer of fuel from the line to the manifold.

Video: how the injector works The most complex component of the entire system is its "brain" (ECU), it is presented in the form of a mini-computer. Contains a program designed to quickly analyze all parameters of the motor and the appropriate response to existing changes.

Therefore, in order to ensure adequate operation of the injector, it will be indispensable catalytic converter(burns out unburned fuel particles) and an oxygen sensor (sends data to the control unit about the state of the fuel mixture and exhaust toxicity). Without this information, the operation of the entire device will be incorrect.

Advantages and disadvantages

Undoubtedly, each device has some disadvantages. But if they do not complicate a person's life, then you should not worry too much. The injector is characterized by many "strengths". Among the advantages of such systems are:

• savings in fuel mixture consumption (in comparison with carburetor engines);
• an increase in the power of the unit (and at reduced operating speeds in particular);
• simplified and fully automated engine start;
• optimal maintenance of the required idle speed;
• advanced features in the matter of controlling the operation of the motor;
• absence of necessity manual adjustment injection systems;
• reduction of toxic waste in emitted gases;
• good protection of the vehicle from possible theft;
• lack of interdependence between the operation of the unit and atmospheric pressure, which simplifies the operation of the car in the mountains or in other areas with possible pressure drops.

The advantages are listed, but this does not mean that there will be no “surprises”. That is why it is important to consider the disadvantages as well. As for them, here it is impossible not to note:

• high requirements for the composition of the fuel mixture used;
• the need to use special equipment for the diagnosis and further maintenance of injection engines;
• high dependence on power supply and increased sensitivity to direct voltage;
• very high pressure of the fuel mixture, which means that in case of an accident there is a high probability of fire and explosion (in modern cars, a controller is installed to prevent such undesirable consequences).

Of course, the injector cannot be called simple device, but, given its role in increasing the power and environmental friendliness of the engine, it is worth thinking about purchasing a car of this particular type, especially since the repair injection unit- is no longer a problem. Determining what is wrong with the injection device is simple: there are failures when starting the car engine. After studying the article, some of them can be eliminated on their own.

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Over time, the basics of the automotive industry have changed and become more and more distant from their origins. Thus, the fuel system of vehicles was subjected to constant modernization until a universal injector appeared, used in the design of most gasoline cars and today. Injection power engine fuel, in fact, does not have any special wisdom and difficulties, however, to understand the principles and meaning of its operation, it would not be superfluous to familiarize yourself with it in more detail. It is about the typical design and operation of modern injectors that will be discussed in today's material. Interesting? Be sure to scroll down the page.

A bit of history

Despite its popularity only in the mid-80s of the 20th century, fuel injector appeared much earlier. According to official data, the first injector engine make-up installations began to be tested and used in the early 30s of the last century. In those days, the device and operation of the injector were painfully primitive, so these nodes were used only on relatively unpretentious units from the field of military aviation. In general terms, the fuel distribution mechanisms of those years were completely mechanical design and performed their functions quite well.

Note that the first purpose of the injectors was not to reduce the amount of fuel consumed by vehicles or improve environmental friendliness exhaust gases, but in increasing engine power. In part, injection systems justified themselves in this regard, but in the early 40s in military sphere jet engines began to be actively used, so the first ones instantly lost their current relevance. On top of that, the operation of mechanical type injectors did not allow to obtain maximum efficiency from aircraft engines, because carburetors at that time were more flexible in terms of adjusting to the engine operating mode.

However, the "second life" of the fuel system based on the injector began in the mid-80s, they gradually became regulars in the automotive industry. It was not the unique design of the node that played a big role here, but the possibility of reducing emissions harmful substances in exhaust gases during use. By the way, the old mechanical injectors lagged far behind the existing carburetors in all respects, therefore automotive engineers were forced to radically redesign the injection power system. Note that they succeeded, because it is not for nothing that the injectors remain the main components of the fuel systems of cars.

The device and principles of operation of the injector

Injector (from English - "injector") - in general concept, this is a device in the form of a jet pump, which is designed to pump liquid, semi-liquid or gas masses into a certain container. In the case of a car injector, there are no features in the interpretation of this concept. The only thing is that the injector unit in the design of the machine is understood not as a separate pump (injector), but as a combination of them together with other units that form a single fuel system. A typical version of an automobile injector device corresponds to the following diagram:

The injector, in other words, the pump presented above, is controlled by a special unit with an electronic microcircuit. It is he who, based on the readings of many sensors such as speed identifiers, crankshaft position or engine temperature, performs the dosage and competent injection of fuel into the combustion chambers of the engine.

A typical device of an injector as a single system involves the combined use of the following elements:

• nozzles and injector chambers connected to them (that is, several pumps noted above, combined into a synchronized system);
• control unit (electronic brain of any injector system, naturally, controlling the injector);
• a catalytic converter (otherwise called an “afterburner”, which burns out all the fuel that has not burned out inside the engine and left the combustion chambers along with the exhaust gases);
• additional components (wiring connecting the injectors and the control unit, fuel lines that ensure the delivery of fuel to the distribution mechanism, a gasoline pump, etc.).

As you can see, the operation of the injector is arranged without much difficulty. Of course, repairing such a fuel system is by no means easy, but you can understand the principles of its operation completely and without any problems.

Interesting! For the first time, the injectors of the above description were applied German companies- Bosch and Mercedes-Benz, in 1951 and 1954 respectively. At first, such systems were expensive and pointless to use due to the presence of carburetors familiar to everyone, but with the advent of more environmental requirements To the safety of exhausts, top auto concerns began to actively use injectors.

Types and technical characteristics of injection systems

To date, officially used in automotive industry Only two types of injectors are considered:

• electronic injector. A node of this type works strictly according to the principle described above. That is, the fuel is delivered to the injectors, and then, through the use of an electronic control unit, it is correctly dosed and competently fed into the combustion chambers of the engine. The operation of electronic type injectors is most convenient for the trouble-free operation of any car, which is why they are used in the design of almost all modern cars;
• mechanical injector. The same node is deprived of head control in the form of an electronic "brain". To be more precise, the operation of a mechanical type injector is based on adjusting the fuel supply to the engine using its valves (dosing occurs by connecting the nozzles to the valves with special tubes, the former, based on the degree of openness of the latter, supply optimal amount fuel to the engine). Units with such a device were considered some kind of innovation in the "injector" field, but in a short time they managed to prove their inconsistency and to this day are not used in serial production of machines.

Regardless of the type of node, it is customary to highlight its main properties. Today, among the technical characteristics of the injector, it is worth highlighting one point, or rather, the method of fuel injection into the engine. Of course, the nozzles in any injection system carry out direct fuel injection into the cylinders (intake manifold), but the principles of gasoline delivery may differ. So, there are injectors:

• With single injection ( central injection). In such systems, there is only one nozzle, which supplies fuel to the engine. Today, single-injection injectors are not used, so there is no need to focus on them;
• With distributed injection - the most used at the moment. Their design assumes that the injector consists of the nth number of nozzles that supply fuel to each individual cylinder. Among injection systems with distributed injection, several subtypes are distinguished, or rather:
  • direct injection (often called direct) - fuel enters the combustion chamber directly;
  • simultaneous injection - fuel is supplied synchronously by all nozzles to each engine cylinder;
  • pairwise-parallel injection - fuel enters according to the paired scheme of operation of the nozzles (that is, one pump operates on the “inlet”, the other on the “outlet”);
  • phased injection - gasoline is supplied exclusively to the "inlet" in any mode of operation.

It should be noted that such a wide variety of injectors is only partly justified, since in the vast majority of cases systems with either direct or simultaneous types of injection are used.

Advantages and disadvantages of injectors

At the end of today's material, it will not be superfluous to pay attention to what the injector is good for, and what it can cause trouble to any motorist. Let's start, perhaps, with the advantages of injection systems, which include the following provisions:

• Profitability. We can definitely say that the injectors work exclusively for their "owner" compared to the same carburetors. Surprisingly, to some extent similar fuel distribution units with the same engine operating modes supply less fuel to it. This is largely due to the thoughtful design of the injector and the presence of electronic control;
• Getting more efficiency from the engine. Again, amazing. Despite the smaller amount of fuel supplied to the engine, when using an injector, it is possible to achieve from the power unit more power. This is also due to the well-organized device of the node, and especially its electronic component;
• Environmental friendliness. Everything is extremely simple here, because in the structure of any injector there is a catalytic converter, which makes it more environmentally friendly, burning out the unburned fuel in the engine;
• Job stability. We repeat, due to a well-organized device, the injectors are completely independent in their functioning from weather conditions or similar moments.

Among the shortcomings of injection systems, it is worth highlighting only one aspect, namely, their repair and partly operation. In this regard, injectors are rather whimsical and inconvenient for their owners. In particular, if you want to successfully use a node of this type, any motorist needs:

• be prepared for expensive repairs in the event of a breakdown;

In the late 60s and early 70s of the XX century, the problem of environmental pollution by industrial waste arose, among which a significant part was car exhaust gases. Until that time, the composition of combustion products of engines internal combustion no one was interested. In order to maximize the use of air in the combustion process and achieve the maximum possible engine power, the composition of the mixture was adjusted so that it contained an excess of gasoline.

As a result, oxygen was completely absent in the combustion products, but unburned fuel remained, and substances harmful to health are formed mainly during incomplete combustion. In an effort to increase power, designers installed accelerator pumps on carburetors that inject fuel into the intake manifold with each sharp press on the accelerator pedal, i.e. when you need a sharp acceleration of the car. In this case, an excessive amount of fuel enters the cylinders, which does not correspond to the amount of air.

In urban traffic, the accelerator pump works at almost all intersections with traffic lights, where cars must either stop or move quickly. Incomplete combustion also occurs when the engine is running at idling especially during engine braking. When the throttle is closed, air flows through the carburetor idle channels with high speed sucking in too much fuel.

Due to the significant underpressure in the intake manifold, little air is sucked 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 unburned fuel remains in the exhaust gases. The described engine operation modes sharply increase the content of toxic compounds in combustion products.

It became obvious that in order to reduce harmful emissions into the atmosphere for 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 an exhaust gas catalytic converter. But the catalyst works effectively only when the so-called normal fuel-air mixture is burned in the engine (weight ratio air / gasoline 14.7: 1). Any deviation of the composition of the mixture from the specified one led to a drop in the efficiency of its work and accelerated failure. To maintain this ratio working mixture carburetor systems no longer fit. Only injection systems could become an alternative.

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

The way out was found next. Feedback was introduced into the injection system - in exhaust system, directly in front of the catalyst, they put an oxygen content sensor in the exhaust gases, the so-called lambda probe. This system was developed already taking into account the presence of such an element fundamental for all subsequent systems as an electronic control unit (ECU). According to the signals from the oxygen sensor, the ECU adjusts the fuel supply to the engine, accurately maintaining the desired mixture composition.

To date, 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).

Fuel injection systems have the following main advantages over carburetor systems:

• accurate dosing of fuel and, consequently, more economical fuel consumption.
• reduction of toxicity of exhaust gases. It is achieved due to the optimality of the fuel-air mixture and the use of exhaust gas parameters sensors.
• increase in engine power by about 7-10%. Occurs by improving the filling of cylinders, optimal installation ignition timing corresponding to the operating mode of the engine.
• improvement dynamic properties car. The injection system immediately responds to any load changes by adjusting the parameters of the fuel-air mixture.
• ease of starting regardless of weather conditions.

Device and principle of operation (on the example of an electronic system of distributed injection)

In modern injection engines, an individual nozzle is provided for each cylinder. All nozzles are connected to fuel rail where the fuel is under pressure, which creates an electric fuel pump. The amount of injected fuel depends on the duration of the injector opening. The moment of opening is regulated by the 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. The mass air flow is measured, which is then recalculated by the program into cylinder cyclic filling. In the event of a sensor failure, its readings are ignored, the calculation is based on emergency tables.

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

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

The crankshaft position sensor is used for general synchronization of the system, calculation of 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 operation of the system is impossible. This is the only "vital" sensor in the system, in which the movement of the car is impossible. Accidents of all other sensors allow you to get to the car service 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 control to adjust the amount of fuel supplied. The oxygen sensor is used only in systems with a catalytic converter for Euro-2 and Euro-3 toxicity standards (Euro-3 uses two oxygen sensors - before and after the catalyst).

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

Listed here are just some of the main sensors required for the system to function. Complete set of sensors for various cars depend on the injection system, on toxicity standards, etc.

About the results of a survey of sensors defined in the program, the ECU program controls executive mechanisms, which include: injectors, gasoline pump, ignition module, idle speed controller, canister valve of the gasoline vapor recovery system, cooling system fan, etc. (again, everything depends on the specific model)

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

Types of fuel injection systems

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

single point injection simpler, it is less stuffed with control electronics, but also less efficient. The control electronics allows you to take information from the sensors and immediately change the injection parameters. It is also important that carburetor engines are easily adapted for mono-injection with almost no structural alterations or technological changes in production. Single-point injection has an advantage over a carburetor in terms of fuel economy, environmental friendliness and relative stability and reliability of parameters. But in the throttle response of the engine, single-point injection loses. Another disadvantage: when using a single-point injection, as well as when using a carburetor, up to 30% of gasoline settles on the walls of the manifold.

Single-point injection systems, of course, were a step forward compared to carburetor power systems, but no longer meet modern requirements.

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

• the possibility of automatic adjustment at different speeds and, accordingly, an improvement in the filling of the cylinders, as a result, at the same maximum power the car accelerates much faster;
• gasoline is injected near the intake valve, which significantly reduces the loss of sedimentation in the intake manifold and allows for more precise adjustment of the fuel supply.

As next and effective remedy in optimizing the combustion of the mixture and increasing efficiency gasoline engine implements simple
principles. Namely: it sprays fuel more thoroughly, mixes it better with air and more competently disposes of the finished mixture on different modes engine operation. As a result, direct injection engines consume less fuel than conventional "injection" engines (especially when quiet ride at low speed) with the same working volume, they provide more intensive acceleration of the car; they have cleaner exhaust; they guarantee higher liter output due to the higher compression ratio and the effect of cooling the air when the fuel evaporates in the cylinders. At the same time, they need quality gasoline low in sulfur and mechanical impurities to ensure normal work fuel equipment.

And just the main discrepancy between 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 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 nozzle holes and plunger pairs pumps. As a result, wear is reduced operating pressure pump and the quality of gasoline spraying deteriorates. All this is reflected in the characteristics of the engines and the uniformity of their work.

The first to use a direct injection engine stock car Mitsubishi. Therefore, consider the device and principles of operation direct injection on the example of a GDI (Gasoline Direct Injection) engine. The GDI engine can operate in ultra-lean air-fuel mixture combustion mode: the ratio of air and fuel by weight is up to 30-40:1.

Maximum possible for traditional injection engines with port injection the ratio is 20-24: 1 (it is worth recalling that the optimal, so-called stoichiometric, composition is 14.7: 1) - if the excess air is greater, the lean mixture simply will not ignite. On GDI engine the atomized fuel is in the cylinder in the form of a cloud concentrated in the area of ​​​​the spark plug.

Therefore, although the mixture is over-lean in general, it is close to the stoichiometric composition at the spark plug and is easily ignited. At the same time, the lean mixture in the rest of the volume has a much lower tendency to detonate 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 the fuel is injected and evaporated into the cylinder, the air charge is cooled - the filling of the cylinders improves somewhat, and the likelihood of detonation again decreases.

The main design differences between GDI and conventional injection:

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

• High-pressure nozzles with swirl atomizers create the shape of the fuel jet, in accordance with the engine operating mode. In the power mode of operation, injection occurs in the intake mode and a conical air-fuel jet is formed. In the ultra-lean mixture mode, injection occurs at the end of the compression stroke and a compact air-fuel is formed.
  a torch that the concave piston crown sends directly to the spark plug.
• Piston. A recess is made in the bottom of a special shape, with the help of which the fuel-air mixture is directed to the area of ​​​​the spark plug.
• inlet channels. On the GDI engine, vertical intake channels are used, which ensure the formation of the so-called in the cylinder. “reverse vortex”, directing the air-fuel mixture to the candle 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

In total, there are three modes of engine operation:

• Super-lean 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 euro modifications).

Super-lean combustion mode(fuel injection on the compression stroke). This mode is used for light loads: for quiet city driving and when driving outside the city with constant speed(up to 120 km/h). Fuel is injected in a compact jet at the end of the compression stroke towards the piston, bounces off the piston, mixes with air and vaporizes towards the spark plug area. Although the mixture in the main volume of the combustion chamber is extremely lean, the charge in the region of the candle is rich enough to be ignited by a spark and ignite the rest of the mixture. As a result, the engine runs steadily even at a total cylinder air/fuel ratio of 40:1.

The operation of the engine on a very lean mixture set new problem- neutralization of exhaust gases. The fact is that in this mode, their main share is nitrogen oxides, and therefore a conventional catalytic converter becomes ineffective. To solve this problem, exhaust gas recirculation (EGR-Exhaust Gas Recirculation) was applied, which dramatically 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, lowers 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 NOx neutralization only due to EGR, since with an increase in engine load, the amount of bypassed exhaust gas must be reduced. Therefore, an NO-catalyst was introduced to the engine with direct injection.

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

Power mode(injection on the intake stroke). The so-called "mode homogeneous mixture formation» is used for heavy urban driving, high-speed suburban traffic and overtaking. Fuel is injected on the intake stroke with a conical torch, mixing with air and forming a homogeneous mixture, as in conventional engine with distributed injection. The composition of the mixture is close to stoichiometric (14.7:1)

Two stage mode(injection on the intake and compression strokes). This mode allows you to increase the engine torque when the driver, moving at low speeds, sharply presses the accelerator pedal. When the engine is running at low speeds, and a rich mixture is suddenly supplied to it, the likelihood of detonation increases. Therefore, the 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-poor mixture (approximately 60:1), in which detonation processes do not occur. Then, at the end of the bar
compression, a compact jet of fuel is delivered, which brings the ratio of air and fuel in the cylinder to a "rich" 12:1.

Why is this mode introduced only for cars for the European market? Yes, because Japan is characterized by low speeds and constant traffic jams, while Europe is characterized by long autobahns and high speeds (and, consequently, high engine loads).

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

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Which replaced the carburetors. One can argue endlessly about the advantages and disadvantages of it, since there are adherents of both among motorists, and today we will talk about how the injector works. This knowledge will be useful to all motorists whose car is equipped with this node. It never hurts to know how the injector functions and what elements it consists of, as situations may arise that require its repair.

About nozzles and the principle of operation

In fact, an injector in a car is a nozzle that serves to spray not only liquids, in our case, fuel, but also gas. For the first time, this technology was applied back in 1951, but for a long time it was not used in the automotive industry due to its complex design.

Already at the end of the last century, injectors began to spread widely, since performance indicators of these systems were in many ways superior to everyone already familiar with carburetors. As a result, already in the first decade of this year, this system almost completely ousted carburetors from the market. Many modern cars are equipped with a spray-injector.

How it works?

The injector is used to supply the fuel mixture exclusively through direct fuel injection, which is carried out through one or more nozzles. Fuel enters initially into the intake tract of the engine or directly into the working cylinder of the power unit. All cars equipped with such an innovative power system are called injection cars. The classification of such an injection always depends strictly on the principle of operation, the location of the node, and the number of nozzles. As for mono-injection, this system is notable for the fact that the mixture is carried out exclusively by one nozzle in all working cylinders of the internal combustion engine.

Most often such innovation system the power supply of the car's motor is mounted on, that is, on the place where a device such as a carburetor was usually installed. In the automotive industry this system no longer in use and considered obsolete. Many modern machines equipped with systems, that is, there is one nozzle for each cylinder.

It is noteworthy that the injection can be simultaneous, that there is a fuel mixture through the injectors will simultaneously enter the cylinders, as well as paired-parallel, when mechanical drive opens the injectors in pairs.

In this case, one of the injectors fires on the injection, and the other on the outlet. Most often, this type of injection is used at the stage of starting the power unit, as well as in case of malfunctions of the camshaft position sensor.

The principle of operation of the injector of any car is always based on the use of signals coming to the injectors from the microcontroller, and they read data from numerous electronic sensors. They collect data on the intensity of rotation of the crankshaft, instantaneous air consumption, engine temperature, and throttle position.

The central controller processes all this data and only then determines how exactly to supply fuel and when to do it, as well as control the ignition of the fuel mixture. It follows from this that the system modern injector constantly changes the algorithm of work, taking into account the readings of numerous sensors.

What does an injector include?

• A fuel pump is a device that pumps fuel from a tank under pressure;
• Electronic control unit - a device that controls the injection based on sensor data;
• A device for forcing a certain pressure on the nozzles;
• A set of nozzles or one mono nozzle;
• Sensor package.

The principle of operation of the injector and its device is extremely simple and clear, however, there are also characteristic features that all fans of carburetor injection refer to as disadvantages. For example, the cost of individual injector units is quite high, which causes many complications at the stage of system repair. In general, the maintainability is low here, and the requirements for the quality of the fuel mixture are very high.

It is possible to diagnose injector malfunctions, but this requires special equipment, which is also very expensive.

You can talk about how the injector works in a car for a long time if you delve into the operation of each sensor and the central controller. It is worth noting that in all auto settings the power system is radically different, so they cannot be generalized.

About the main problems

The main problem lies in the constant failure of various sensors. Mechanical repair can not always help, since such equipment is, by and large, microcontrollers. For example, the DMRV sensor, which determines the instantaneous air flow, often fails. This phenomenon can be identified signal lamp on the instrument panel, reducing acceleration dynamics, as well as difficulties with starting the power unit when it is warm.

It also makes sense to use diagnostic equipment for the car whenever possible. By visual inspection, it is not always possible to identify a malfunction. If you have a spare analog at hand, then you should try to install it. When the DMRV is disconnected from the network, the motor starts to work in emergency mode. If at the same time the motor will work in the same way as it worked, then the sensor will definitely be replaced.

We can definitely say that the global transition from carburetor injection to injectors turned out to be very successful, despite the numerous shortcomings of this technology. Many today refuse, preferring the injector, as it is much more reliable.

Why choose an injector?

The device of this system is not clear to everyone, but many motorists are inclined to believe that the fuel consumption of a car with an injector is lower. In practice, this rarely happens, since injectors were originally installed not for economy, but in order to ensure uniform injection of the fuel mixture into all cylinders and at a strictly defined moment.

If this car power system starts to work incorrectly over time, then its repair can be quite expensive, since the arrangement of sensors and injectors is quite complicated. Many details are simply not recoverable.

Conclusion

As a result, you have to spend a lot of money on their replacement in a car service. Car injectors can have a different design and size, and from time to time they need to be cleaned, since the quality of fuel in our country is quite low.

The device of the nozzles is such that it is much more difficult to clean them than the same carburetor, so you will not be able to cope with this work on your own. As you can see, there are a lot of shortcomings and difficulties here, but only motorists still prefer the injector. When the system is working properly, and the condition of the car's engine is satisfactory, then no problems will arise. Fuel consumption may not be minimal, but will become stable.