Traditional oil level detection
1. The sliding potentiometer is used as the basic detecting component. The floater drives the potentiometer through the connecting rod, and its resistance value changes with the change of the liquid level, thereby changing the current or voltage signal in the circuit to achieve the purpose of measuring the oil level. Since the potentiometer is a contact type friction device, the resistance value will change when used for a long time, which causes the measurement error to increase or even cannot be used. At the same time, due to the large number of mechanical moving parts of the float type structure, the long-term use is easy to wear and fail;
2. The inductor coil is used as the basic detecting component, the inductor is driven by the float, the oscillation frequency of the oscillation circuit is changed, and the oil level is measured by the frequency detecting circuit. The sensor produced by the method has a complicated structure, troublesome debugging, high use cost, and difficulty being widely used;
3. Install a pressure sensor at the bottom of the fuel tank. Through the conversion of the output pressure value and the oil density, the height value of the oil level in the fuel tank is obtained, and then the oil value in the fuel tank is calibrated according to the height value. The defects of the measurement method are: (1) The pressure guiding hole is easily blocked by oil dust, causing measurement error. (2) Since the height of the fuel tank is generally less than 1 meter, the selected pressure sensor ranges from about 10 kPa, and the specific gravity of the oil is about 0.8. The pressure is below 5kPa, the accuracy of such micro-pressure sensor is low, and it is greatly affected by the outside; (3) The pressure sensor is installed at the drain valve at the bottom of the tank, which cannot be disassembled frequently, affecting the cleaning of the tank; (4) The influence of temperature, the density of the oil will change, affecting the accuracy of the measured value;
4, the principle of the reed pipe measurement, that is, through the float with the liquid level rise and fall, control the principle of the contact opening of the reed pipe, output resistance signal to measure the liquid level change. The defects of this measurement method are: (1) the components are easy to magnetize and the stability is poor, and (2) due to the on-off measurement, the product resolution is limited and the precision is low. (3) There are many floating parts and long-term reliable use. Poor sex.
