Car fuel tank: gas tank device
In our separate article, which describes the components and the principle of operation of the fuel system of the atmospheric injector gasoline engine, we promised our readers to talk about each such element of the system in more detail. Next we will talk about the fuel tank.
Car fuel tank device
The fuel tank usually has such a capacity, which provides approx 500 km of autonomous mileage without refueling. Tanks are different in shape and capacity for a particular car model. The fuel tank is reliably isolated from the outside atmosphere. Ventilation inside the tank is carried out by a special system for trapping gasoline vapors. Fuel tank design prevents fuel leakage and limits emissions from fuel evaporation.
Installation location and insulation
On passenger cars, the tank is most often installed in front of the rear axle. So, it is located under the rear passenger seat. The main task is the location of the tank outside the deformation zone of the body with a strong blow to the rear. The lower part of the tank is additionally closed with metal protection against external damage. The fuel tank is also protected from heat by isolating it from the elements of the exhaust system. To do this, use insulating gaskets.
Materials for production
Fuel tanks are steel or aluminum, and they are made of plastic. Metal tanks are obtained by welding from stamped sheet. Aluminum is great for storing gasoline and diesel fuel, steel tanks are used for gas storage.
Plastic tanks are the most common today, as in the process of their production the simplicity of formation allows to receive any form and volume, they are not prone to corrosion. Plastic tanks are made of several layers to protect against fuel leaks. The inside of the fuel tank is covered with fluorine, which serves as additional protection against leakage.
The following video in its first part allows you to clearly see the installation location and method of mounting the fuel tank in a conventional civilian car.
filler neck
Refueling of the fuel tank is provided through the filler neck. This element is located above the rear wing on the left or right side of the car body. Experts believe that it is more convenient to place the filler neck on the left side. In their opinion, the neck, located behind the driver, reduces the chances of unintentional start of movement and separation of the refueling gun after refueling at the gas station.
The neck is connected to the tank by a pipeline. The section of the filler neck and the pipeline is responsible for the tank filling speed. These elements should provide a figure of about 50 liters per minute. The neck is closed by a locking screw cover. Additionally, there is such a scheme, in which constipation of the neck is absent.
Access to the neck is limited by the fuel filler flap, which has a lock. On modern cars the hatch opens from salon. Structurally it can be used as an electric drive using an electric motor, and a mechanical way of opening by means of a cable.
fuel pipelines
To supply fuel to the engine power supply system, an outlet fuel line is connected to the tank. Excess fuel, unspent nozzles, come back to the tank through the fuel line. In modern vehicles on gasoline directly in the gas tank is a fuel pump. Structurally, the body has access to such a pump. The technological window in the vast majority of cases is realized under a back passenger sofa.
Fuel level sensor in the tank
For petrol units, such a sensor is a single unit with the fuel pump housing. For diesel engines, this sensor is installed separately. The sensor device includes two elements: float and potentiometer.
If the fuel level drops, then the float will drop lower. At the same time, the resistance of the potentiometer will change, which is connected to the float. All this will reduce the voltage in the electrical circuit, and the fuel gauge arrow on the instrument panel will show the changes.
Fuel tank ventilation system
The fuel tank requires constant pressure maintenance, equal to atmospheric. The tank ventilation system is responsible for this. Modern cars are equipped with a closed-type fuel tank ventilation system to prevent potential pressure drops or rises..
If the pressure in the tank drops, then its deformation can occur. At high pressure, the tank may simply rupture.
- When fuel is taken from the tank, it drops the pressure and liquefies (vacuum). The ventilation system qualitatively eliminates such effect. If the pressure in the tank has dropped, then the safety valve will let the required amount of air inside the tank. Such a valve is located in the lid of the filler neck and allows air to the outside only in one direction.
- Excessive air enters the tank during refueling, fuel vapors are formed. The system will effectively displace these surpluses, which are displaced from a special pipe for ventilation. The ventilation pipe is located parallel to the pipe for filling and ends with a tank, in which gasoline vapors accumulate. This tank is connected to the adsorber of the fuel vapor trapping system. The ventilation pipe also has a gravity valve. This valve prevents the risk of fuel spilling from the tank as a result of overturning the car or leaning to 45 ° and more.
- If the fuel in the closed tank heats up, then gasoline vapors appear and the pressure in the tank increases. The ventilation system neutralizes the increase in pressure and equalizes it to atmospheric. In this case, the fuel vapor capture system is directly involved.
In order to increase the efficiency of the gasoline vapor trapping system, additional sensors can be installed inside the tank, measuring fuel temperature and pressure.
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