Fuel level sensor (FST) – a functional device of the fuel system of the car, the only purpose of which is to determine the level and volume of fuel (diesel, gasoline, diesel fuel, oil) in the fuel tank. If only it was damaged in the accident, it is not a problem. But if the main parts of the machine are damaged, it is better to recycle it: https://scrapcar.cash.
The sensor is located in the fuel tank, and the fuel level indicator is displayed on the dashboard in the car. Such control sensors have a very low error (not more than 1%), their design has no moving and quickly wearing elements.
Fuel level sensors can also be used in filling and draining control systems, as well as in satellite vehicle monitoring systems.
How a fuel level sensor is designed
A modern fuel level sensor is nothing else but a displacement sensor-potentiometer. Such device has a number of advantages, such as: availability, reliability and simplicity of sensor design, high accuracy of performed measurements and low price. Among the disadvantages are the presence of individual elements susceptible to oxidation and frequent breakdowns.
Two types of sensors-potentiometers can be used in the fuel system of a car – tubular and lever sensors. The main element of such sensors is the so-called float, which can be made of thin sheet metal, hollow plastic and foam plastic.
Lever fuel sensor
In this type of device, the float is connected to the sensor contact using a small lever made of metal. The lever sensor is a sector that is divided into strips of resistive type metal. The basis of the design are reliable wear-resistant resistors with a thick film.
Such a sensor can be installed either separately or in a block, which is responsible for the fuel supply. The block may consist of a TH and a fuel intake.
Due to their extreme versatility, lever sensors can be used on almost all fuel tanks.
Tubular fuel sensor
In this type of sensor, the float moves inside a hollow tube. Wires that create resistance are also installed in parallel, and there are contact rings for the float at the ends. Tubular sensors are highly resistant to various variations of the TC.
The internal combustion engines, which use new types of fuel, are equipped with special non-contact FLSs. The most famous of such sensors is magnetic inactive sensor (MAPPS).
The main element of such a device is closed, which completely prevents its direct contact with the fuel mixture. The float in the magnetic sensor is connected to the lever by a magnet (hence the name).
The movement of the magnet is exclusively on a sector on which metal plates of different lengths are mounted. The formed magnetic field creates an electrical signal on the surface of the plates, which determines the existing level of fuel mixture in the tank.
How does the fuel level sensor work?
Operating principle of the fuel level sensor is based on the following: a specific fuel level value in the tank creates its own signal on the sensor.
Fuel level measurement with a float switch is performed only when the fuel level in the tank decreases. At the same time initially the level indicator shows that the tank is full, and only after some time there is a gradual decrease in the pointer. During this time interval the level sensors may allow for some error in measurement, which often does not exceed 1%.
Most fuel systems have digital and analog level sensors. The analog type sensor determines the degree of change in voltage on the potentiometer. These sensors have a greater degree of measurement error than their digital counterparts.
The sensor of digital type is designed to convert the analog signal into a corresponding figure with further correction and alignment of the value, taking into account possible fluctuations in the level of TC. Sensors of this type are highly accurate, with an allowable error level of 0.5%.