What is an injector: features and differences from the carburetor
Injection engine (engine with injector, English. Electronic fuel injection engine) - modern type of internal combustion engine, equipped with an injector fuel injection system, which replaced the carburetor engines. Today, new petrol cars are equipped exclusively with injectors, as this solution is able to provide the power plant with the necessary compliance with strict standards for economy and toxicity of exhaust gases.
We also recommend reading the article about it, what is a TDI engine. In this article you will learn about the distinctive features, as well as the advantages and disadvantages of engines of this type.
The carburetor loses to the injector in terms of overall efficiency, as injector engines work more stably, the car gets improved acceleration dynamics. The injector unit consumes less fuel, the content of harmful substances in the exhaust is reduced, as the fuel burns more fully. System management is fully automated (unlike the carburetor), that is, it does not require manual adjustment during operation. As for diesel engines, the system of diesel fuel injection on such engines has a number of design differences, although the general principle of operation of the injector on diesel remains similar to gasoline counterparts.
What is the difference between an injector engine and a carburetor
The injector is a fundamentally different way of supplying fuel to the combustion chamber compared to the carburetor. In other words, in the injector engine the biggest design changes affected the power supply and fuel supply systems. In a carburetor engine, gasoline is mixed with a certain amount of air in the external device (carburetors).
After the resulting fuel-air mixture is sucked into the engine cylinders. The injector engine has special injector nozzles, which dosed fuel injection under pressure, then the portion of fuel is mixed with air. If you compare the efficiency of fuel supply injector and carburetor, the motor with the injector is detected to 15% more powerful. There are also significant fuel savings in different engine modes.
types of injectors
Injector fuel injection systems are divided into several subspecies:
- single point injection (mono prisk);
- distributed injection;
- direct (direct) injection;
This division directly depends on the total number of installed injectors, as well as from the injection site of the fuel itself. One-point system is the earliest development and provides for the presence of only one injector nozzle in the intake manifold. In other words, one injector for all engine cylinders. This solution has a number of disadvantages, which led to its rapid disappearance.
The next round of development of the injector after monovrisku was distributed injection, which means the presence of the collector and individual injectors, which are installed above the intake valve of each cylinder. Direct fuel injection is the latest injector system. The principle of operation is, that the nozzle is installed so, to supply fuel directly to the engine cylinder (directly into the combustion chamber), and not in the collector. The location of the injectors in this system were the cylinder heads. This system is very similar to the principle of fuel supply and mixture formation in diesel engines.
Also, each of the systems is further divided into the type of injection. As for distributed injection, such a decision may be simultaneous (all injectors inject fuel). Also, the injection can be pairwise parallel (nozzles open in pairs), when one injector starts to open before fuel injection, and the other before the release cycle. Phased injection is also noted (the nozzle opens before the intake stroke) and direct injection directly into the cylinder.
How the injector is arranged and works
The injector device basically assumes the presence of the following basic components of the system:
- electronic control unit (ECU);
- electric fuel pump;
- injection nozzles;
- fuel ramp with pressure regulator;
- electronic temperature sensors, the angle of opening of the throttle valve DPDZ, DPKV, DMRV, etc..
To better understand the principle of operation of the injector, let's take a cursory look, how the components of the system interact with each other on the example of a common type of injector engines with multi-point distributed injection. After turning the ignition key, the power is supplied to the electric fuel pump, which is in the fuel tank and immersed in fuel. The specified pump delivers fuel to the fuel line under a certain pressure. Injector nozzles are installed in the fuel rail (rails), through which the supply of fuel to the injectors is implemented, and also fixing of nozzles on an inlet collector is carried out. A fuel pressure regulator is also installed in the ramp, which serves to maintain the difference between the air pressure under the inlet and in the injectors themselves.
Thanks to the installed sensors of the electronic engine control system (ESKD) the ECU controller receives information, on the basis of which it is possible to synchronize injection according to modes and conditions of work of the internal combustion engine. The control unit receives readings from the engine temperature sensor, oxygen sensor, detonation sensor, camshaft position sensor (Hall sensor) and crankshaft sensor. This allows you to adjust the amount of fuel, supplied to each cylinder, flexibly and dynamically change the composition of the fuel-air mixture, etc..
In other words, for accurate fuel injection it is necessary to supply fuel to the injectors under pressure, which creates a fuel pump in the gas tank. The ECU then sends control pulses to the injectors. These pulses cause the nozzle to open for the required period of time, which depends on the specific mode of operation of the engine, load on the motor, the degree of pressure on the accelerator pedal and a number of other factors. Information on the duration of the pulses on the injectors and the required amount of fuel during injection is calculated by the ECU taking into account the readings from electronic sensors.
Sensors detect various changes in engine operation and changing conditions, constantly transmitting signals to the control unit. This scheme allows you to spend a certain amount of fuel during startup, warming up, idling, quiet or dynamic driving, etc..
The specified accuracy during fuel metering is possible only due to the operation of the control electronics of the car in the form of a set of sensors and the ECU engine. Firmware is stitched in the control unit, and the work itself is based on so-called fuel cards. The sensors continuously provide information about the engine operation mode, about the speed of vehicles, etc.. The controller receives and processes data, then determines the required number of fuel injections and their duration over time. Any changes in the operation of the internal combustion engine are read by sensors and force the ECU to dynamically make adjustments to the operation of the injector.
The outstanding environmental friendliness of the injector was made possible by the presence of an oxygen sensor (lambda probe). This sensor is in the exhaust system and "assesses" the condition of the exhaust gases. Based on his testimony, the ECU impoverishes or enriches the fuel-air mixture (changes the ratio of air and fuel in the working mixture) during engine operation in most standard modes.
Advantages and disadvantages of injector engines
If you compare the injector with the carburetor, then the first solution is more convenient to operate, but definitely more expensive and more difficult to repair. A simple carburetor is a mechanical device, which requires periodic maintenance. Carburetor engines are more coking, can barely run in the cold season, overspend fuel, also the motor can work unstable in strong heat, etc..
The carburetor has less life than the injector. For this reason, the carburetor must be cleaned constantly, rinse and adjust. The indisputable advantage of the carburetor is its simplicity and unpretentiousness to fuel quality, thanks to which almost every car owner can learn to repair and adjust the carburetor with their own hands in their garage.
We also recommend reading the article about the carburetor injection device. In this article you will learn about the principles of operation, carburetor adjustment and maintenance features.
In the case of injector engines, the main advantages are: economy, easy start of the engine and stability of work of the motor in any conditions, as well as low fuel consumption. The motor with the injector responds better to the accelerator pedal, spark plugs are not so often and heavily filled with gasoline, the engine is less prone to coking. It is much more difficult to determine the fault of the injector in case of failure.
Frequent injector malfunctions
Since the injector is a complex multicomponent system, over time, individual elements may fail. The main task of the injector is the maximum possible efficiency of fuel combustion, which is achieved by maintaining a clearly defined composition of the working mixture of fuel and air.
- As a result, any failure of electronic sensors leads to an imbalance in the operation of the entire injection system, can float idle or in motion, the engine may start 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. The power unit in this situation is not gaining momentum, on the dashboard lights "check", etc..
- Another cause of injector malfunctions is contamination of the filter elements in the fuel supply system or the injector injectors themselves as a result of the use of low quality gasoline. The fuel filter must be replaced in time to maintain efficiency. Not less attention, especially on cars with more mileage 50-70 thousand. Km, deserves a mesh filter of the fuel pump. It is recommended to change or clean the specified grid of the petrol pump. It is also desirable once every few years to wash the fuel tank in parallel with the replacement or cleaning of the specified filter mesh coarse cleaning of the fuel pump.
Note, that it is important to identify and troubleshoot the injector in a timely manner, as failures in its work can significantly worsen the overall condition of the engine and lead to other breakdowns. As for clogging the fuel injectors, in this case the engine starts worse, loses power and starts consuming more fuel. Violation of the shape of the fuel spray torch (especially in direct injection motors) leads to local overheating, engine detonation, burnout of valves, etc.. - The injectors can also "pour" fuel, that is, do not close after the pulse from the ECU stops. In this case, the excess fuel enters the combustion chamber, can then enter the exhaust system and the engine lubrication system due to leaks in the places of installation of the piston rings. In such situations, the whole engine suffers greatly, as gasoline dilutes the oil and the oil of the loaded parts deteriorates. The presence of fuel in the exhaust system disables the catalytic converter (catalyst), which cleans exhaust gases from harmful compounds.
The injector must be cleaned periodically to prevent malfunction of the injector. The point is, that the presence of fractions and impurities in gasoline gradually contaminates the injectors, which reduces their productivity, and also violates the quality of fuel spray. There are two ways to clean the nozzles: with removal or directly on the car. The procedure for cleaning injectors on the car involves that, that a special flushing fluid for cleaning the injector is passed through the injectors. The method is, that the fuel line is disconnected from the fuel rail, then instead of the petrol pump in system the special compressor instead of the petrol pump starts to pump washing liquid.
Another option for cleaning the injector is cleaning with the removal of nozzles in an ultrasonic bath or on a special flushing stand. As for ultrasound, nozzles are placed in a special device or bath, where wave oscillations "break" the sediment. Flushing the injectors with removal on the stand is a procedure, when simulating the operation of the injectors in the engine, at the same time instead of gasoline washing liquid is passed through them. Note, that each of these methods has its advantages and disadvantages, which can be read in our separate article on flushing nozzles.
Tips and tricks
Operation of the car on fuel in the conditions of the CIS obliges the owner to carry out replacement of the fuel filter every 10-15 thousand. Km. mileage and periodic cleaning of injector nozzles. It is desirable to carry out this procedure every 30-35 thousand. Km. mileage. Additionally, it is recommended to buy fuel only at large gas stations with a good reputation.
For the purpose of prevention it is possible to use special cleaners of fuel system, which are filled with fuel to keep the injector clean. Note, that these fuel additives should be used only on new cars or after deep cleaning of the fuel system. If the nozzles are already dirty, then the injector must be flushed separately.
Don't wait for that moment, when symptoms of injector contamination appear in the form of engine problems. It is better to wash the nozzles in advance. Example, before every other scheduled MOT. pay attention, in the case of using the method of cleaning flushing fluids, it is optimal to carry out this procedure before changing the engine oil.
Finally, let's add, that the reduction in the performance of the injectors can be caused by problems with the fuel pump. In this case, it is necessary to measure the pressure in the fuel rail. If the indicators are lower than recommended, then you will need to remove the diagnostic pump. It should also be considered, that the installation of more productive injectors during tuning and boosting the engine may require mandatory replacement of the fuel pump.
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