Engine
Engine
Posted By nextmg

How does the fuel-injected engine?


Injection engine – it’s quite a complex mechanism, whose work should be well established in order to get the best performance from it. The article discussed in detail the principle of operation of the injection engine.

Injection system Engine 2107

Before we start talking about this miracle of technology, dispel some myths. Injection engine does not give it much greater power than the carburetor. The increase will amount to a maximum of 10%.

Abu Chevrolet Lacetti

Center of the entire system is the ECU (electronic control unit). He has many names, the “brains”, “computer”, and so on. In fact, yes, it is a computer, which is laid a huge number of tables on the composition of the mixture, the fuel injection timing and other things. For example, if the engine speed equal to 1500, the throttle valve is opened at 10 degrees, and the air flow rate is 23 kg, it will flow into the cylinder one fuel. If the input parameters are changed, the result will be different. If the control unit there are some problems, for example, flies flashing, all turns to dust, the engine starts or how horrible work, or stops altogether.

Sensors injection engine

All elements can be divided into actuators and sensors. To start with we will look at the sensors.

This element is set to the air filter, right at the entrance. At the heart of his work is the principle difference between readings. Thus, the two platinum wires passes electricity. Depending on their temperature resistance varies. One of the yarns securely sheltered from the air flow, which makes its resistance constant. The second stream is cooled, and based on the difference values for the same tables, which are described above, the ECU calculates the quantity of air.

It is used either as an alternative to or together with the above-described higher accuracy for readout. In short, it has two chambers, one of which is sealed and in absolute vacuum. The second camera is connected to the intake manifold, where a vacuum is created during the intake stroke. Between these cameras have a diaphragm, as well as piezoelectric. They generate a voltage when driving the diaphragm. Then the signal goes to the computer.

If you look at the crankshaft pulley injection engine, you can see it fits. She’s magnetic. The entire perimeter of the teeth are set. In total, there should be 60 pieces, every 6 degrees. But two of them are not, they need to be synchronized. The crankshaft position sensor is composed of a magnetized steel heart, as well as a copper coil. With the passage of teeth in the winding of the induction current occurs, the voltage of which depends on the rotational speed of the pulley.

Sensor phases (DF)

Not all engines are equipped with them before, but now it can be found almost everywhere. It works on the principle of a Hall sensor, i.e. a disc with a coil as well as cut. Once slit falls on the sensor output voltage across it is zero. It is necessary for that computer to generate the voltage for the ignition cylinder in the right, as well as to control ticks. For example, the nozzle is not opened during the power stroke.

Knock Sensor Nissan Terrano

It is installed on the cylinder block injection engine. As soon as the engine there is a knocking on the block transmitted vibration. The sensor is a piezoelectric element, which generates voltage, the stronger the vibration, the higher the voltage. Accordingly, the control unit on the basis of his testimony adjusts ignition timing. But more on that later.

In essence, it is a regular pot. The reference voltage on it, is typically 5 volts. So, depending on what angle the throttle valve is deflected, the voltage varies at the control output. It’s simple.

This sensor is needed to determine the temperature of the engine. If the carburettor engine it is necessary simply to turn on and off the fan, then here it is a more complex device. This thermal resistance whose value varies depending on temperature. Accordingly, the voltage changes, when passing through it.

It is installed in the exhaust system, there are systems with two sensors. His task – to monitor the amount of free oxygen in the exhaust gases. For example, if it is too much, then it means that all of the mixture is not combusted and, hence, must be enriched. If the oxygen is less than is listed in the standard computer tables, it is necessary to impoverish.

Let’s start with the power supply system. This ensures high-quality spray of fuel into the cylinders. As soon as the engine speed is increased, and increased appetite, and thus in the ramp should be served more fuel to save pressure. The pump runs faster on command of the control unit. Most modern cars, dating from about 2013 model year, equipped with the fuel module, which includes a built-in pump and filter. This significantly affects the cost of replacing the filter, because it is necessary to change the whole module. Some manufacturers in the instructions written that the module is set for life cars, but do not believe that any filter is able to take place over 2 seasons.

Injector Ford Transit

After the fuel has passed all the wire circuit, it enters the nozzle, which dispenses it over the cylinder. The nozzle is a solenoid valve of very small diameter, which provides the fuel sprayed into the combustion chamber. ECU adjusts the amount of fuel which is supplied by means of time intervals while the nozzle is open. Typically, this tenth of a second.

All we ever saw carburetor, looked at him from above. So it had a flap that covered the air. Here, the same principle. Perhaps, and there is nothing more to tell.

The regulator of idling (IAC)

This is also a solenoid valve, which closes the duct rod extending bypass throttle. Depending on the voltage which it supplies the control unit, it opens this same channel.

In principle, it is the same ignition coil, only four of them here. When current flows through the primary winding in the secondary switched high-voltage high-frequency current, which is fed to a candle.

So, after we sorted out the major sites of the injection engine, see how it works. After starter cranked crankshaft DPKV said control unit, which cylinder is in what position. In turn, the phase detector reported strokes. The control unit has taken note of this information and opened the nozzle in the cylinder in which the intake stroke starts. But I opened it for a reason, and for a strictly defined period of time that corresponds to the indications on the tables DMRV or DBP. So fuel mixture formed.

After the intake stroke is ended, the compression begins at this time takes place the inlet in the other cylinder. Here, the piston reaches top dead center, as evidenced by DPKV and Fs, respectively, it is time to apply voltage to the ignition module at the right cylinder. For this is two transistors, which take on the two cylinders in the control unit.

Further, when the explosion occurred, the computer looks at the knock sensor readings and adjusts ignition timing even for the next along the cylinder. But that is not all. Thereafter, when the gases have reached the oxygen sensor, the control unit adjusts the composition of the mixture, namely, the injector opening time which allows the best use of the fuel and its combustion. If the computer detects a lack of oxygen, but the throttle valve is open, then it reopened control idling.

This point should be considered separately, so to speak, is a small clarification. So, warm-engine mode has nothing to do with the testimony of some of the sensors, ie, they are not dependent on anything. In particular, it DMRV and DBP as well as the knock sensor. In the block, as already mentioned, some laid tables, a lot of them, millions. So, during the warm-up mode, the ECU operates strictly according to these tables and nothing else. This means that if it is written in the air fuel ratio of 14.1 to 1, then so be it. This figure is generally accepted norm for the operating temperature. So, until the engine temperature reaches that specified in the firmware of the control unit, the warm-mode is turned off. After the computer starts to work on the sensors.

What better injector or carburetor engine?

This issue is quite controversial, at each point of view there are many opponents and supporters both among ordinary drivers, and among professionals who fully understand the principle of operation of the injection engine. So carburetor engine distinguished by simplicity and transparency of the work. That is, if the mechanic adjusted the idle, so they stayed.