Automotive fuel injector structure principle fuel injector failure phenomenon

What is a car injector? I believe that our friends basically have a **** the same question in mind. The injector is a very important part of the gasoline EFI device, which regulates fuel injection. If something goes wrong, it will affect the normal operation of the engine and make the engine abnormal or stop immediately. According to the different structure of the fuel injection port, the fuel injector can include pin type and hole type. Here is a look at the structural principles of automotive fuel injectors with the automotive editors on this site.

Structural Principles of Automotive Fuel Injectors &mdash&mdash Introduction

The fuel injector is a key component of the gasoline EFI unit, which regulates the final injection of fuel. If there is any doubt, the engine will not work properly or stop working immediately. If the injector is installed in the original carburetor position and combined with the throttle, this form is called single-point electronically controlled fuel injection. It has the advantage of low cost and simple maintenance, but the disadvantage is that due to the unequal distance between the injection point and each cylinder, the fuel is not evenly distributed, and the fuel tends to stick to the intake pipe wall during cold engine startup.

If the injector is mounted on the intake pipe of each cylinder, this form is called multi-point electronically controlled fuel injection device, which is currently used in most gasoline EFI engines. Its advantage is that each cylinder basically has its own injector, the injector as close as possible to the intake valve, preventing the shortcomings of the single-point EFI, the disadvantage is the high cost and complex maintenance. At present, most automobile engines basically use multi-point injection, a few economical cars with single-point EFI. If an old carburetor engine is converted to EFI, a single-point EFI is used.

Most of the car electronically controlled gasoline injection device consists of three parts: oil supply part, gas supply part and regulation part. Fuel supply part by the car tank, gasoline pump, gasoline filter, pressure regulator and fuel injector composition. The gasoline pump pumps gasoline out of the car tank and filters impurities through the gasoline filter. The pressure regulator pressurizes the gasoline so that the pressure of the gasoline is higher than the negative pressure of the intake manifold, and then it is delivered to the injector of each cylinder through the fuel line. The injector is the equivalent of a switch, and the component that regulates the switch is the electronic control unit.

The injectors are regulated by a solenoid coil, whose current is turned on and off by the electronic control unit. Electronic control unit according to the sensor feedback signal processing, and send an electrical signal to the injector, the injector to determine the injector to start injecting gasoline time. This time distance is called &ldquofuel injector; pulse width&rdquo. The electromagnetic coil of the injector is energized to generate a magnetic field, under the action of the magnetic field, the plunger overcomes the spring force to be suctioned up, together with the valve body to leave the valve seat, gasoline is sprayed from the nozzle under pressure; when the electromagnetic coil is de-energized, the magnetic field disappears, and the plunger moves downward under the action of the spring force, and the valve body leans against the The valve seat seals the nozzle mouth, so that gasoline can not come out. The valve body is divided into ball valve and needle valve according to the structure. In order to ensure the accuracy of the injection, the ball valve or needle valve and the valve seat basically need to have a high production processing accuracy, the valve body has a very small lift of only 0.1 mm or so, due to the role of the pressure regulator, the front of the injector is a high-pressure fuel line, behind the intake manifold of low pressure, through the development of change, the pressure difference into negative pressure, which ensures that the fuel through the development and change in the form of a mist sprayed near the intake valve.

Structural Principles of Automotive Injectors &mdash&mdashInjector Testing Methods

1. While the starter is driving the engine, listen to the injectors with a long-handled screwdriver or stethoscope. Click, click&rdquoIf it is difficult to judge the working sound due to other noises, you can use the method of pulling out and then plugging in the injector harness plug to identify whether the injector is working or not during auscultation.

2. If the injector does not work, connect the test light to the injector harness plug and start the engine. If the test light blinks, it means that the injector regulating system is working properly and the fault lies in the injector. To test the injector, use a multimeter to measure the resistance of its solenoid coil. A normal resistance value indicates that the injector is clogged (the relationship between the carbon produced by combustion and the gum in the fuel.) This phenomenon is the most common), stuck needle valve, etc. , the injector should be overhauled, cleaned or replaced; if the resistance value is abnormal, the injector must be replaced.

3. If the test light does not come on, it means that there is a problem with the regulating system or circuit of the injector. In this regard, first of all, we must check whether the relevant circuit of the injector is intact, only the external circuit is intact in order to determine the computer has a fault.

Structural principles of automotive injectors &mdash&mdash injector maintenance

After 700 hours of work, the injector should be tested and adjusted once. If the opening pressure is lower than the specified value of more than 1Mpa or the needle valve head of the carbon is serious, the needle valve should be removed into the clean diesel fuel, scrape off the carbon with wood chips, and use a fine steel wire to dredge the spray hole. After installation should be good debugging, the same machine cylinder injection pressure difference should be less than 1Mpa.

In order to make the injector sprayed into the cylinder diesel fuel immediately and completely burned, must be regularly maintained oil pump oil supply time. If the oil supply time is too early, the car will have trouble starting and popping the cylinders. If the fuel supply time is too late, the exhaust will emit black smoke, the engine temperature will be too high, and fuel consumption will increase.

The matching precision of the injector needle valve coupling is extremely high and the diameter of the spray hole is very small, so it is necessary to strictly follow the seasonal changes and use the specified brand of clean diesel fuel, otherwise the injector will not work properly.

When cleaning the injector needle valve coupling, it is not allowed to collide with other hard objects or fall to the ground to avoid collision wear. Replacement of injector needle valve coupling, the new coupling will be immersed in 80 ℃ hot diesel fuel for about 10s, to be completely dissolved in anti-rust oil, and then clean diesel fuel in the body of the valve back and forth to pump the needle valve and rinse thoroughly, to prevent the injector work due to the dissolution of anti-rust oil and stick to the needle valve.

Whether the injector can work properly depends on whether we maintain it properly. Check whether the injector is spraying oil:When the oil pump works normally, check the injector. Start the engine, touch the injector with a stethoscope and listen to the noise. No noise, the injector does not work. Then, connect a large impedance test light to the injector's harness plug to start the engine. If the test light is on, the injector adjustment circuit is normal, the fault is in the injector, should be replaced. If the test light does not come on, the fault is in the injector regulation circuit. I hope that the information shared by Bianshao Automobile about the structural principle of automobile fuel injector can solve the problem for friends.

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