For everyone modern cars With gasoline engines, an injection fuel supply system is used, since it is more advanced than a carburetor system, despite the fact that it is structurally more complex.

Injection engine- not new, but it became widespread only after the development electronic technologies. This is because it was very difficult to mechanically organize control of a system with high operating accuracy. But with the advent of microprocessors this became quite possible.

The injection system differs in that gasoline is supplied in strictly specified portions forcibly into the manifold (cylinder).

The main advantage of the injection power system is compliance with optimal proportions constituent elements combustible mixture on different modes work power plant. Thanks to this it is achieved the best way out power and economical gasoline consumption.

System design

The fuel injection system consists of electronic and mechanical components. The first controls the operating parameters of the power unit and, based on them, sends signals to activate the executive (mechanical) part.

The electronic component includes a microcontroller (electronic control unit) and a large number of tracking sensors:

• crankshaft position;
• mass flow air;
• provisions throttle valve;
• detonation;
• coolant temperature;
• air pressure in the intake manifold.

Injector system sensors

Some cars may have several additional sensors. They all have one task - to determine the operating parameters of the power unit and transmit them to the ECU

As for the mechanical part, it includes the following elements:

• electric fuel pump;
• fuel lines;
• filter;
• pressure regulator;
• fuel rail;
• injectors.

Simple fuel injection system

How it all works

Now let’s look at the principle of operation of an injection engine separately for each component. With the electronic part, in general, everything is simple. Sensors collect information about rotation speed crankshaft, air (entered into the cylinders, as well as its residual part in the exhaust gases), throttle position (connected to the accelerator pedal), coolant temperature. The sensors constantly transmit this data to the electronic unit, due to which high accuracy of gasoline dosage is achieved.

The ECU compares the information received from the sensors with the data entered in the maps, and based on this comparison and a series of calculations, it controls the executive part. The electronic unit contains so-called maps with optimal operating parameters of the power plant (for example, for such conditions it is necessary to submit as many - so much gasoline, for others - so much).

First injection Toyota engine 1973

To make it clearer, let us consider in more detail the algorithm of operation of the electronic unit, but according to a simplified scheme, since in reality a very large amount of data is used in the calculation. In general, all this is aimed at calculating the time length of the electrical pulse that is supplied to the injectors.

Since the diagram is simplified, we assume that the electronic unit carries out calculations only on several parameters, namely the base time pulse length and two coefficients - coolant temperature and oxygen level in exhaust gases. To obtain the result, the ECU uses a formula in which all available data is multiplied.

To obtain the basic pulse length, the microcontroller takes two parameters - the crankshaft rotation speed and the load, which can be calculated from the pressure in the manifold.

For example, the engine speed is 3000, and the load is 4. The microcontroller takes this data and compares it with the table included in the card. IN in this case we get a basic pulse length of 12 milliseconds.

But for calculations it is also necessary to take into account the coefficients, for which readings are taken from the coolant temperature sensors and the lambda probe. For example, the temperature is 100 degrees, and the oxygen level in the exhaust gases is 3. The ECU takes this data and compares it with several more tables. Let's assume that the temperature coefficient is 0.8 and the oxygen coefficient is 1.0.

Having received all the necessary data, the electronic unit carries out the calculation. In our case, 12 is multiplied by 0.8 and 1.0. As a result, we find that the pulse should be 9.6 milliseconds.

The described algorithm is very simplified, but in reality, more than a dozen parameters and indicators can be taken into account in the calculations.

Since data is constantly supplied to the electronic unit, the system almost instantly reacts to changes in engine operating parameters and adapts to them, ensuring optimal mixture formation.

It is worth noting that the electronic unit controls not only the fuel supply, its task is also to adjust the ignition angle to ensure optimal engine operation.

Now about the mechanical part. Everything is very simple here: a pump installed in the tank pumps gasoline into the system, under pressure, to ensure forced supply. The pressure must be certain, so a regulator is included in the circuit.

Gasoline is supplied through the highways to a ramp, which connects all the injectors. An electrical impulse supplied from the ECU causes the injectors to open, and since gasoline is under pressure, it is simply injected through the opened channel.

Types and types of injectors

There are two types of injectors:

1. With single point injection. This system is outdated and is no longer used on cars. Its essence is that there is only one nozzle, installed in the intake manifold. This design did not ensure uniform distribution of fuel throughout the cylinders, so its operation was similar to a carburetor system.
2. Multipoint injection. Modern cars use this type. Here, each cylinder has its own nozzle, so this system is characterized by high dosage accuracy. The injectors can be installed in either intake manifold, and into the cylinder itself (injection).

A multipoint fuel injection system can use several types of injection:

1. Simultaneous. In this type, an impulse from the ECU is sent to all injectors at once, and they open together. This type of injection is not currently used.
2. Paired, also known as pairwise-parallel. In this type, the injectors work in pairs. It is interesting that only one of them supplies fuel directly during the intake stroke, while the second does not have the same stroke. But since the engine is 4-stroke, with valve system valve timing, then the mismatch of injection on the stroke does not affect the performance of the engine.
3. Phased. In this type, the ECU sends signals to open for each injector separately, so injection occurs with a coincident timing.

It is noteworthy that a modern fuel injection system can use several types of injection. So, in normal mode, phased injection is used, but in the event of a transition to emergency operation (for example, one of the sensors has failed), the injection engine switches to twin injection.

Sensor feedback

One of the main sensors, based on the readings of which the computer regulates the opening time of the injectors, is the lambda probe installed in the exhaust system. This sensor determines the residual (unburnt) amount of air in the gases.

Evolution of the lambda probe sensor from Bosch

Thanks to this sensor, the so-called “ Feedback" Its essence is this: the ECU carried out all the calculations and sent an impulse to the injectors. The fuel entered, mixed with air and burned. The resulting exhaust gases with unburned mixture particles are removed from the cylinders through the exhaust system exhaust gases, in which the lambda probe is installed. Based on its readings, the ECU determines whether all calculations were carried out correctly and, if necessary, makes adjustments to obtain the optimal composition. That is, based on the already completed stage of fuel supply and combustion, the microcontroller makes calculations for the next one.

It is worth noting that during the operation of the power plant there are certain modes in which the readings oxygen sensor will be incorrect, which may disrupt the operation of the engine or a mixture with a certain composition is required. In such modes, the ECU ignores information from the lambda probe, and it sends signals to supply gasoline based on the information stored in the cards.

In different modes, feedback works like this:

• Start the engine. In order for the engine to start, you need an enriched fuel mixture with an increased percentage of fuel. And the electronic unit provides this, and for this it uses the specified data, and it does not use information from the oxygen sensor;
• Warm up To make the injection engine dial faster operating temperature The ECU sets increased engine speed. At the same time, it constantly monitors its temperature, and as it warms up, it adjusts the composition of the combustible mixture, gradually depleting it until its composition becomes optimal. In this mode, the electronic unit continues to use the data specified in the maps, still not using the lambda probe readings;
• Idling. In this mode, the engine is already completely warmed up, and the temperature of the exhaust gases is high, so the conditions for the correct operation of the lambda probe are met. The ECU is already starting to use the readings of the oxygen sensor, which makes it possible to establish the stoichiometric composition of the mixture. With this composition it is ensured highest yield power plant power;
• Movement with a smooth change in engine speed. For achievement economical consumption fuel at maximum power output, a mixture with a stoichiometric composition is needed, therefore, in this mode, the ECU regulates the supply of gasoline based on the readings of the lambda probe;
• A sharp increase in speed. In order for an injection engine to respond normally to such an action, a slightly enriched mixture is needed. To ensure this, the ECU uses map data rather than lambda probe readings;
• Motor braking. Since this mode does not require power output from the engine, it is enough that the mixture simply does not allow the power plant to stop, and a lean mixture is also suitable for this. To display it, the lambda probe readings are not needed, so the ECU does not use them.

As you can see, although the lambda probe is very important for the operation of the system, the information from it is not always used.

Finally, we note that although the injector is a structurally complex system and includes many elements, the breakdown of which immediately affects the functioning of the power plant, it ensures more rational gasoline consumption and also increases the environmental friendliness of the car. Therefore, there is no alternative to this power system yet.

Autoleek

Ministry of Education and Science of the Russian Federation

Syktyvkar Forestry Institute branch

Federal State Budgetary Educational Institution

higher professional education

St. Petersburg State Forestry University

them. S.M.Kirova

BLTP Faculty

Department of A&A

Laboratory work No. 1,2

Discipline: TEA

Subject: Injection engine power supply system.

Completed by T. P. Arteeva, gr. 141

Checked by A. N. Yushkov, Ph.D.

Head Department Chudov V.I., Ph.D.

Syktyvkar – 2011

Contents Introduction………………………………………………………………………………………...3

Injection engine power supply system............4

Main malfunctions of the power system.……...………………………7

1. Sensors………………………………………………………………………………….7

   Injectors……………………………………………………………..9

   Fuel pump……………………………………………………………..11

Maintenance of the power system………….………………..………………………….12

Introduction

Today, the injection engine has almost completely replaced the outdated carburetor system.

An injection engine improves the vehicle's performance and power performance (acceleration dynamics, environmental performance, fuel consumption, etc.).

The injector allows long time keep high environmental standards, without manual adjustments, thanks to self-tuning using the oxygen sensor.

Injection engine. Main advantages.

The main advantages of an injector compared to a carburetor: reduced fuel consumption, improved acceleration dynamics, reduced emissions harmful substances, stability of work. Changing electronic injection parameters can literally occur “on the fly”, since control is carried out by software, and can take into account practically a large number software functions and data from sensors. Also, modern electronic injection systems are able to adapt the operating program to a specific engine, to the driver’s driving style, etc.

Injection engine. Flaws.

The main disadvantages of injection engines compared to carburetor engines: high cost of repairs, high cost of components, non-repairability of elements, high requirements for fuel quality, specialized equipment is required for diagnostics, maintenance and repair.

Engine fuel injection systems are classified as follows. Single injection or central injection - one nozzle for all cylinders, located in place of the carburetor (in the intake manifold). IN modern engines does not occur. Distributed injection - each cylinder is served by a separate isolated nozzle in the intake manifold. Simultaneous - all injectors open simultaneously. Pair-parallel - the injectors open in pairs, with one injector opening immediately before the intake cycle, and the second before the exhaust stroke.

1. Injection engine power system design

Fig.1. Fuel supply diagram for an engine with a fuel injection system

1 – nozzles; 2 – fitting plug for monitoring fuel pressure; 3 – injector ramp; 4 – bracket for fastening fuel pipes; 5 – fuel pressure regulator; 6 – adsorber with solenoid valve; 7 – hose for suction of gasoline vapors from the adsorber; 8 – throttle assembly; 9 – two-way valve; 10 – gravity valve; 11 – safety valve; 12 – separator; 13 – separator hose; 14 – fuel tank plug; 15 – filling pipe; 16 – filling pipe hose; 17 – fuel filter; 18 – fuel tank; 19 – electric fuel pump; 20 – fuel drain line; 21 – fuel supply line.

Fuel is supplied from a tank installed under the bottom in the rear seat area. The fuel tank of the VAZ 2111 is made of steel and consists of two stamped halves welded together. Filler neck connected to the tank with a gas-resistant rubber hose secured with clamps. The plug is sealed. The fuel pump is electric, submersible, rotary, two-stage, installed in the fuel tank. The developed pressure is at least 3 bar (3 atm).

The VAZ 2110 fuel pump is turned on at the command of the injection system controller (with the VAZ 2112 ignition on) via a relay. To access the pump under back seat There is a hatch in the bottom of the car. From the pump, fuel under pressure is supplied through a flexible hose to the filter fine cleaning and then - through steel fuel lines and rubber hoses - to the fuel rail.

The fine fuel filter is non-separable, in a steel housing, with a paper filter element. There is an arrow on the filter housing that must coincide with the direction of fuel movement.

The fuel rail serves to supply fuel to the injectors and is mounted on the intake manifold. On one side there is a fitting for monitoring the fuel pressure, on the other there is a pressure regulator. The latter changes the pressure in the fuel rail - from 2.8 to 3.2 bar (2.8-3.2 atm) - depending on the vacuum in the receiver, maintaining constant drop between them. This is necessary for accurate dosing of fuel by injectors.

The fuel pressure regulator VAZ 2111, VAZ 2112 is fuel valve, connected to a spring-loaded diaphragm. The valve is closed under the action of the spring. The diaphragm divides the regulator cavity into two isolated chambers - “fuel” and “air”. The “air” is connected by a vacuum hose to the receiver, and the “fuel” is connected directly to the ramp cavity. When the engine is running, the vacuum, overcoming the resistance of the spring, tends to retract the diaphragm, opening the valve. On the other hand, fuel presses on the diaphragm, also compressing the spring. As a result, the valve opens and part of the fuel is released through the drain pipe back into the tank. When you press the gas pedal, the vacuum behind the throttle valve decreases, the diaphragm, under the action of a spring, closes the valve - the fuel pressure increases. If the throttle valve is closed, the vacuum behind it is maximum, the diaphragm pulls the valve harder - the fuel pressure decreases. The pressure difference is set by the spring stiffness and the size of the valve opening and cannot be adjusted. The pressure regulator is non-separable; if it fails, it is replaced.

The injectors are attached to the ramp through rubber sealing rings. The injector is an electromagnetic valve that allows fuel to pass through when voltage is applied to it, and closes under the action of a return spring when there is no power. At the injector outlet there is a nozzle through which fuel is injected into the intake manifold. The injection system controller controls the injectors. If there is a break or short circuit in the injector winding, it should be replaced. If the injectors become clogged, they can be washed without dismantling at a special service station.

The feedback injection system uses the VAZ 2110 fuel vapor recovery system. It consists of an adsorber installed in the engine compartment, a separator, valves and connecting hoses. Fuel vapor from the tank partially condenses in the separator, and the condensate is drained back into the tank. The remaining vapor passes through gravity and two-way valves. The gravity valve prevents fuel from leaking out of the tank when the VAZ 2111 car rolls over, and the two-way valve prevents excessive increase or decrease in pressure in the fuel tank.

Then the fuel vapors enter the VAZ 2110 adsorber, where they are absorbed by activated carbon. The second fitting of the adsorber is connected by a hose to the throttle assembly, and the third to the atmosphere. However, when the engine is turned off, the third fitting is closed by an electromagnetic valve, so that in this case the adsorber does not communicate with the atmosphere. When the engine starts, the injection system controller begins to send control pulses to the valve with a frequency of 16 Hz. The valve communicates the adsorber cavity with the atmosphere and the sorbent is purged: gasoline vapors are sucked through the hose into the receiver. The greater the engine's air consumption, the longer the duration of the control pulses and the more intense the purging.

In an open-loop injection system, the fuel vapor recovery system consists of a separator with a two-way check valve. The VAZ 2111 air filter is installed in the front left part of the engine compartment on three rubber holders (supports). The filter element is made of paper; when installing, its corrugations should be located parallel to the axis of the car. After the filter, the air passes through the mass air flow sensor and enters the intake hose leading to the throttle body. The throttle assembly is fixed to the receiver. By pressing the gas pedal, the driver slightly opens the throttle valve, changing the amount of air entering the engine, and therefore the combustible mixture - after all, the fuel supply is calculated by the controller depending on the air flow. When the engine is running Idling and the throttle valve is closed, air flows through the idle air control valve - a valve controlled by the controller. The latter, by changing the amount of supplied air, maintains the idle speed specified (in the computer program). The idle speed regulator of the VAZ 2112 is non-separable; if it fails, it is replaced.

Injection engine - what do we know about it? This is what is equipped with any modern car. Realization of the resource of such an engine internal combustion(ICE) is designed for economical consumption fuel, minimizing its emissions in environment. Let's carry out small excursion to study the unit.

What does it work on?

They work in beats; each cycle provides the operation:

1. Filling cylinders with fuel.
2. Compressing it with a piston for combustion.
3. The working stroke is the production of mechanical energy by detonation of a flammable substance.
4. Discharge of processed raw materials into the atmosphere.

The most popular in the auto industry are 4-wheelers with gasoline traction. Using their example, we will study the principle of operation of an injection engine.

During the first stroke, the piston moves down as much as possible - gasoline mixed with air is supplied through the valve. Next, the piston rises all the way, closing the valve and compressing the mixture. After this, the spark plug cuts off the spark - it starts the detonation of the compressed substance.

An increase in temperature in the chamber and the formation of gases move the piston forward, and the crankshaft, due to inertia, returns it to the top position. At high speed rpm, the pressure builds up even more, the outlet valve opens. Gasoline processing products rush towards it.

For more efficient functioning, a set of sensors is used that determine the load received on the mechanisms and calculate portions of the components of the detonating mixture to ensure movement with a cycle equal to the beat.

Their software is designed in such a way that each operates in parallel with the motor modes, monitors changes in cycles and adapts to them. This functionality allows you to adjust fuel consumption to your individual driving style and increase efficiency.

What are the features of the device?

Studying the design will allow you to understand in more detail how an injection engine works. Components characteristic of this type:

• Block electronic control(ECU);
• Pressure regulator;
• Injectors;
• Gasoline pump;
• Sensors

Interaction of the above: sensors receive data about the state of mechanics or processes, they are processed by the processor and transmit control commands. The injectors are given a limited charge, which opens them. The result is that the mixture from the fuel compartment enters the intake manifold compartment.

To make the diagram of this process more understandable, we will carry out short excursion on the design of some of the components that make up the engine injector.

ECU

Its main function is to uninterruptedly issue commands to the components of the car based on the processed information. It includes:

• environmental factors (temperature, humidity, etc.);
• the degree of load on the mechanics (when climbing a hill, moving along bad road, etc.);
• engine mode (idle/high speed, taking into account the load when switching to four-wheel drive, etc.).

In case of discrepancies original program The computer sets adjustments to the performing elements. The unit is capable of diagnostics. The driver is notified of the failure of any executing mechanism or its incorrect functioning by means of the CheckEngine indication on the dashboard. Information about errors is collected in the memory department, which when serious breakdowns helps to quickly detect and eliminate them.

Types of embedded memory devices:

• One-time programmable read-only memory (PROM) - contains the base program code(“brain” of the car). Its chip is located on the panel board; if it fails, it can easily be replaced with a new one. In case of any failures, the embedded codes remain stored on it.
• Random Access Memory (RAM) is a temporary reservoir used to process tasks for the current session. The device is soldered to the board; When the power supply from the battery is stopped, all information from it is erased.
• Electrically programmable (EPROM) - contains temporary data and anti-theft coding. It uses a built-in battery for power, which is recharged while moving. Through it, the embedded codes are compared electronic lock and the same immobilizer parameters. If they do not match, starting the injection engine is impossible.

Injectors

Through them, portions of the fuel mass are released into the manifold and cylinder compartments, and the opening/closing of the valve is repeated many times within a second.

Based on the method of hardware control and the number of parts used, they are divided into categories:

1. Throttle single injection (TBI) - the supply of raw materials for detonation is carried out in one part. The supplied jet is not synchronized with the operation of the intake valve. The control signals for the injector communication are generated from the intra-collector chip. The principle is common on old engines from the 90s.
2. Multiport Injection (MFI) - used in all modern cars with on-board computer. Fuel transfer occurs as a complete set: one nozzle - one cylinder. The injector block is mounted on top of the manifold, and the entire process is synchronized with the central control unit, in accordance with how the ignition system of an injection engine works. When comparing the summary characteristics of predecessors, the efficiency is increased to 10%.

MFI elements for jet supply are: electrohydraulic, electromagnetic, piezoelectric. They are used for injection distribution:

• Simultaneous (synchronous filling of all cylinders);
• Pair-parallel - one pair of pistons takes the lower position, the other - the upper. Filling of fuel and removal of combustion products are carried out in the same way;
• Two-stage (phase) - the transfer of fuel to the combustion chambers is carried out in two operations.
• Direct - used in engine designs that involve burning a composition that is ultra-depleted in oxygen.

An important fact: TBI technology is practically not widespread today, since it is less economical and unreliable!

Catalytic converter

This device allows you to reduce the content of substances such as carbon monoxide and nitrogen in the exhaust gases by converting them into hydrocarbons. It is not controlled by the ECU, but interacts with the processing center through a sensor that determines the percentage of oxygen in the exhaust accumulations. If there is excess fuel supply, the controller receives information from the sensor and corrects it.

The converter contains ceramic elements with built-in catalysts:

• oxidative (platinum and palladium);
• restorative rhodium;
• selective;
• cumulative.

On a note: leaded gasoline is detrimental to the operation of neutralizers, and refueling substances with high content sulfur will render storage catalysis elements unusable!

Sensors

The coordinated operation of all mechanisms of injection engines is ensured by the readings of mini-devices attached to the aggregate performers. Each device measures the parameters of the controlled area and transmits them to the computer.

Built-in sensors ®:

1. MAF (R mass air flow) - mounted at the inlet air filter. It operates on the principle of comparing readings. Current flows through 2 platinum threads. Resistance changes (depends on temperature). In this case, one thread is blown freely, the second is hermetically sealed. Due to the difference that appears, the ECU makes a calculation.
2. DBP (R absolute pressure and temperature in the engine) - combined or placed separately from the previous one. It consists of 2 chambers: one is sealed (vacuum inside), the second is supplied directly to the manifold inlet chamber. A diaphragm passes between the chambers, piezoelements are fixed, which create tension when it moves.
3. DPKV (R crankshaft position) - installed in the form of a magnetic comb on the crankshaft pulley. It is equipped with 58 teeth and 2 gaps equal to the tooth pitch. The teeth move in the copper winding, which, when interacting with the magnetized core, forms an induction voltage - it depends on the speed of the pulley.
4. DF (R phases) - contains a disk with a coil and a slot. The slot turns to the device - the output voltage is equalized to zero. At the same time, the compression top dead center in the first cylinder is reached. Thanks to this, the central unit produces voltage in correct cylinder for ignition, controls the strokes.
5. DD (R detonation) - the cylinder block is equipped with it. At the moment of detonation, vibration passes through it. The transmission of information is based on the generation of free current voltage - it increases with greater vibration.
6. TPS (R throttle position) - with a reference voltage of 5 V, it increases or decreases due to a change in the rotary angle of the valve.
7. DTOZH (R coolant temperature).
8. Oxygen sensor - for different designs implemented singly or in pairs. Takes measurements of free oxygen in exhaust products. Its function allows the ECU to determine whether the fuel mixture is rich or lean.

Injector significantly better than a carburetor. To see this, let’s look at a comparison of similar motor designs in the table:

Fuel system of cars with electronic injection has a number of features compared to a carburetor engine. Let's talk about how the fuel injector system works, its main task and structure.

Device

The task of the fuel supply system is to ensure that the required amount of fuel is supplied to the engine at all operating modes. Fuel is supplied to the engine by injectors installed in the intake pipe. The injector fuel supply system includes the following elements:

• fuel filter 6;
• fuel lines - supply 8 and drain 7;
• injector ramp with fuel injectors 9;
• fuel pressure regulator 4;
• fuel pressure control fitting 1.

Fuel supply system for injection engine

Electric fuel pump

The electric fuel pump is structurally included in the electric fuel pump module installed on injection vehicles inside the fuel tank. The module includes the pump itself, a fuel level indicator sensor, a filter and a swirler for separating steam bubbles.

The electric fuel pump forces fuel from the fuel tank into the fuel supply line. On injection cars, a submersible type module is used, that is, it is located directly in the fuel tank and is cooled by gasoline. The fuel pressure created by the pump is significantly greater than that required for normal operation engine in any mode.

The electric fuel pump is controlled by the system controller through a separate relay. The relay prevents fuel supply when the ignition is on and the engine is not running.

Fuel filter

The fuel supply system is designed for fine adjustment amount of fuel entering the engine. Dirt in the fuel can cause unstable work injectors and pressure regulator, their rapid wear. Therefore, special requirements are placed on fuel cleanliness.

The fuel supply system has a filter. The fuel filter is based on a paper element with a porosity of about 10 microns. The filter replacement interval depends on the filter size and the degree of fuel contamination.

Fuel lines

There are direct and return fuel lines. Direct is intended for fuel coming from the electric fuel pump module to the fuel rail. The return delivers excess fuel after the pressure regulator back to the tank.

Fuel rail

Fuel rail for injection engine
Fuel fills the fuel rail and is distributed evenly to all injectors. On the fuel rail, in addition to the injectors, there is a fuel pressure regulator and a pressure control fitting in the fuel system. Dimensions and design ramps eliminate local fuel pressure pulsations due to resonances during injector operation.

Fuel pressure control

The amount of fuel injected should depend only on the injection duration - the time the injector is open. Therefore, the difference between the fuel pressure in the fuel rail and the pressure in the intake pipe (pressure drop across the injectors) must remain constant. The fuel pressure regulator is used for this purpose. It allows excess fuel to flow back into the tank.

Electromagnetic injector

Main fuel dosing device. The electromagnetic injector has a valve needle with a mounted magnetic core.

When at rest, the spiral spring presses the valve needle against the sealing seat of the nozzle and closes the fuel outlet. When passing electric current the core with the valve needle rises (by 60-100 microns), and fuel is injected through a calibrated hole. Depending on the injection method, engine speed and load, the switch-on time is 1.5-18 ms. The dependence of the amount of fuel passing through the injector on the opening time at a constant pressure difference is the most important indicator of the operation of the injector.

You should not replace the injectors on your car with expensive ones from a foreign car. Usually, good results this does not work; a more effective method is to clean the injectors. From the above we see that the nozzle is a very important component of the injection system. Therefore, it requires a lot of attention.

How does it work?

For normal engine operation, it is necessary to ensure the flow into the engine combustion chamber. air-fuel mixture optimal composition. The mixture is prepared in the intake pipe by mixing air and fuel. The controller supplies the injector with a control pulse, which opens the normally closed injector valve, and fuel under pressure is sprayed into the inlet pipe in front of the valve.

Since the fuel pressure differential is kept constant, the amount of fuel supplied is proportional to time, during which the injectors are in open state. Controller supports optimal ratio air-fuel mixture by changing the pulse duration. An increase in the duration of the injection pulse leads to an increase in the amount of supplied fuel - an enrichment of the mixture. Reducing the duration of the injection pulse leads to a decrease in the amount of fuel supplied, that is, to depletion.

Along with the precise dosage of the injected fuel mass, it has important and injection moment. Therefore, the number of injectors corresponds to the number of engine cylinders.

Injection engine (engine with injector, English electronic fuel injection engine) - modern type ICE equipped with an injection system fuel injection, which replaced engines with a carburetor. Today new gasoline cars are equipped exclusively with an injector, since this decision is able to provide the power plant with the necessary compliance with strict standards regarding efficiency and exhaust gas toxicity.

The carburetor is inferior to the injector in terms of general efficiency indicators, since injection engines operate more stable, the car receives improved acceleration dynamics. The injection unit consumes less fuel, the content of harmful substances in the exhaust is reduced, as the fuel burns more fully. The system control is fully automated (unlike a carburetor), that is, it does not require manual adjustment during operation. Concerning diesel engines, the diesel fuel injection system on such engines has a number of design differences, Although general principle The operation of the injector on a diesel engine remains similar to its gasoline counterparts.

How does an injector work?

The injection system includes several additional elements, including sensors, a controller, a fuel pump, and a pressure regulator. The controller receives information from numerous sensors that report to the electronics about air flow, crankshaft speed, coolant temperature, car voltage, throttle position and many other important data. Based on the information received, the controller (or ECU - electronic control unit) dispenses the fuel supply and controls other systems and vehicle devices, ensuring the most optimal engine operating mode.

The injector operation diagram can be considered in another way: an electric pump pumps fuel, a pressure regulator ensures the difference in pressure in the injectors and the intake manifold, and the controller, receiving information from sensors, controls engine systems, incl. fuel supply, ignition distribution.

Pros and cons of the injector

One of the main advantages is lower fuel consumption compared to a carburetor engine due to point injection. Also, precise dosing ensures virtually complete combustion fuel in the cylinders, which reduces the toxicity of exhaust gases. As a result of the operation of the injector, the engine operates at its most optimal mode, which increases its power (by about 5-10%) and extends its service life.

Other advantages include easier startup in winter time(no heating required) and quick response to load changes, which improves the dynamic properties of the car. But there are some downsides: the injector is more expensive carburetor system, and its repair is quite complicated and expensive. If carburetor maintenance often comes down to washing and purging, then for high-quality diagnostics of the injector alone, special equipment is required, which, taking into account Russian specifics, is not available in every car service.

Injector operation diagram

If you don't get into the wilds " electronic brain" of our car, then the injector operation diagram is as follows. Numerous sensors receive information about: crankshaft rotation, air flow, engine coolant temperature, throttle valve, engine detonation, fuel consumption, speed limit, about voltage on-board network auto and so on.

Controller receiving this information about the parameters of the car, controls systems and devices, in particular: fuel supply, ignition system, idle speed control, diagnostic system, and so on. The change in operating parameters of the injection injection system changes systematically, based on the data obtained.

The device of a simple injector

The injector includes such actuators as:

• fuel pump (electric),
• ECU (controller),
• pressure regulator,
• sensors,
• nozzle (injector).

Accordingly, the injector circuit: an electric fuel pump supplies fuel, a pressure regulator maintains the pressure difference in the injectors (nozzles) and the air in the intake manifold. The controller processes information from sensors: temperature, detonation, camshaft and crankshaft, and controls ignition systems, fuel supply, and so on.

The fuel injection system is good for everyone, but it is not without its own characteristics. Adherents of carburetors call them disadvantages. The features of the injector can safely be called: the fairly high cost of the injector components, low maintainability, high requirements for the quality and composition of the fuel, the need special equipment for diagnostics, and high cost repair work.

Now, let's move on from the story about how the injector works and looks like to a visual aid. You will see in the video the principle of operation of the injector, and everything that is written above will immediately become clear to you.

A LITTLE HISTORY

Such a power system has been actively installed on cars since the mid-80s, when environmental emission standards began to be introduced. The very idea of ​​an injection power system appeared much earlier, back in the 30s. But then the main task was not in environmentally friendly exhaust, but in increasing power.

The first injection systems were used in combat aviation. At that time, it was completely mechanical design, which performed its functions quite well. With the advent jet engines, injectors have practically ceased to be used in military aircraft. On cars, the mechanical injector was not particularly widespread, since it could not fully perform its assigned functions. The fact is that the engine modes of a car change much more often than those of an airplane, and mechanical system I didn’t have time to adjust to the engine’s operation in a timely manner. In this regard, the carburetor won.

But the active development of electronics gave a “second life” to the injection system. And the struggle to reduce emissions of harmful substances played an important role in this. In search of a replacement for the carburetor, which no longer met environmental standards, the designers returned to the injection system, but radically revised its operation and design.

TYPES OF INJECTORS

The first injectors that began to be used en masse on gasoline engines were still mechanical, but they were already starting to have some electrical elements, contributed better work motor.

A modern injection system includes a large number electronic elements, and the entire operation of the system is controlled by a controller, also known as an electronic control unit.

There are three types in total injection systems, differing in the type of fuel supply:

1. Central;
2. Distributed;
3. Direct.

1. CENTRAL

The central injection system is now obsolete. Its essence is that fuel is injected in one place - at the entrance to the intake manifold, where it is mixed with air and distributed among the cylinders. In this case, its operation is very similar to a carburetor, with the only difference being that the fuel is supplied under pressure. This ensures its atomization and more better mixing with air. But a number of factors could affect the uniform filling of the cylinders.

Central system It was distinguished by its simplicity of design and quick response to changes in the operating parameters of the power plant. But it could not fully perform its functions. Due to the difference in filling the cylinders, it was not possible to achieve desired combustion fuel in the cylinders.

2. DISTRIBUTED

Distributed system - on this moment the most optimal and used on many cars. With this injector, fuel is supplied separately to each cylinder, although it is also injected into the intake manifold. To ensure separate supply, the elements that supply fuel are installed next to the cylinder head, and gasoline is supplied to the valve operating area.

Thanks to this design, it is possible to achieve compliance with the proportions of the air-fuel mixture to ensure the desired combustion. Cars with such a system are more economical, but at the same time the power output is greater, and they pollute the environment less.

To the disadvantages distributed system refers to a more complex design and sensitivity to fuel quality.

3. DIRECT

System direct injection at the moment - the most perfect. It differs in that the fuel is injected directly into the cylinders, where it is mixed with air. This system is very similar in operating principle to a diesel one. It allows you to further reduce gasoline consumption and provides greater power output, but it is very complex in design and very demanding on the quality of gasoline.

ELECTRONIC COMPONENT

The main element of the electronic part of the system is the electronic unit, consisting of a controller and a memory unit. The design also includes a large number of sensors, based on the readings of which the ECU controls the system.

For its operation, the ECU uses sensor readings:

1. Lambda probe. This is a sensor that detects the remaining unburned air in the exhaust gases. Based on the lambda probe readings, the ECU evaluates whether the mixture is formed in the required proportions. Installed in the exhaust system of the car.
2. Mass air flow sensor (abbr. MAF). This sensor determines the amount of air passing through the throttle assembly when it is sucked into the cylinders. Located in the air filter element housing;
3. Throttle position sensor (abbr. TPS). This sensor provides a signal about the position of the accelerator pedal. Installed in throttle assembly;
4. Power plant temperature sensor. Based on the readings of this element, the mixture composition is adjusted depending on the engine temperature. Located near the thermostat;
5. Crankshaft position sensor (abbr. DPKV). Based on the readings of this sensor, the cylinder into which a portion of fuel must be supplied, the time of gasoline supply, and sparking are determined. Installed near the crankshaft pulley;
6. Knock sensor. Necessary for identifying formation detonation combustion and taking measures to eliminate it. Located on the cylinder block;
7. Speed ​​sensor. It is needed to create impulses from which the speed of the car is calculated. Based on his readings, adjustments are made fuel mixture. Mounted on the gearbox;
8. Phase sensor. It is designed to determine the angular position of the camshaft. May not be available on some vehicles. If this sensor is present in the engine, phased injection is performed, that is, the opening impulse is received only for a specific injector. If this sensor is not present, then the injectors operate in pair mode, when the opening signal is sent to two injectors at once. Installed in the block head;

Now briefly about how everything works. The electric fuel pump fills the entire system with fuel. The controller receives readings from all sensors and compares them with the data stored in the memory unit. If the readings do not match, it adjusts the operation of the power system so as to achieve maximum agreement between the received readings.

data stored in the memory block.

As for the fuel supply, based on data from sensors, the controller calculates the opening time of the injectors to ensure optimal quantity supplied gasoline to create the air-fuel mixture in the required proportion.

If any of the sensors breaks down, the controller goes into emergency mode. That is, it takes the average value of the readings faulty sensor and uses them for work. In this case, the functioning of the motor may change - consumption increases, power decreases, and interruptions occur. But this does not apply to the DPKV; if it breaks down, the engine cannot function.

What is the difference between an injection engine and a carburetor engine?

An injector is a fundamentally different way of supplying fuel to the combustion chamber compared to a carburetor. In other words, in injection engine largest design changes affected the power and fuel supply systems. IN carburetor engine gasoline is mixed with a certain part of the air during external device(carburetor). After the formed fuel-air mixture is sucked into the engine cylinders. An injection engine has special injection nozzles that inject fuel under pressure in doses, after which the portion of fuel is mixed with air. If we compare the efficiency of fuel supply by an injector and a carburetor, an engine with an injector turns out to be up to 15% more powerful. Significant fuel savings are also noted at different engine operating modes.

Frequent injector malfunctions

Since the injector is a complex multi-component system, over time individual elements may fail. The main task of the injector is the highest possible efficiency of fuel combustion, which is achieved by maintaining a strictly defined composition working mixture fuel and air. As a result, any malfunction electronic sensors leads to an imbalance in the operation of the entire injection system, the speed may fluctuate at idle or while driving, the engine may stall or not start, there is a change in the color of the exhaust, etc.

In some cases, the ECU may put the engine into emergency mode. Power unit in such a situation, it does not pick up speed, “check” lights up on the dashboard, etc. Another cause of injector malfunctions is contamination of the filter elements in the fuel supply system or the injection nozzles as a result of using gasoline Low quality. To maintain performance, the fuel filter must be changed promptly. The fuel pump mesh filter deserves no less attention, especially on cars with mileage of more than 50-70 thousand km. It is recommended to change or clean the specified fuel pump mesh.

It is also advisable to wash the fuel tank once every few years in parallel with replacing or cleaning the specified filter mesh rough cleaning fuel pump. Note that it is important to identify and repair injector malfunctions in a timely manner, since malfunctions in its operation can significantly worsen the overall engine condition and lead to other damage. Regarding clogging fuel injectors, in this case, the engine starts worse, loses power and begins to consume more fuel. Violation of the fuel spray pattern (especially in engines with direct injection) leads to local overheating, engine detonation, valve burnout, etc.

Also, the injectors may “spill” fuel, that is, they may not close after the impulse from the ECU stops. In this case, excess fuel enters the combustion chamber and can then penetrate into exhaust system and into the engine lubrication system through leaks at installation sites piston rings. In such situations, the entire engine suffers greatly, since gasoline dilutes the oil and lubrication of loaded parts deteriorates. Availability of fuel in exhaust system disables catalytic converter(catalyst), which cleans exhaust gases from harmful compounds.

To prevent injector malfunctions, the injectors must be cleaned periodically. The fact is that the presence of fractions and impurities in gasoline gradually contaminates the injectors, which reduces their performance and also impairs the quality of fuel atomization. There are two ways to clean the injectors: by removing them or directly on the car. The procedure for cleaning injection nozzles on a car involves passing a special agent through the injectors. flushing fluid for cleaning the injector.

The method consists in disconnecting the fuel line from the fuel rail, after which, instead of a fuel pump, a special compressor begins pumping flushing fluid into the system instead of a fuel pump. Another option for cleaning the injector is cleaning by removing the nozzles in an ultrasonic bath or on a special washing stand. As for ultrasound, nozzles are placed in a special apparatus or bath, where wave vibrations “break” deposits. Washing injectors with removal on a stand is a procedure in which the operation of injectors in an engine is simulated, and instead of gasoline, flushing liquid is passed through them.