1. Select the sliding potentiometer as the base to view the component. The floater moves through the connecting rod to move the potentiometer. The resistance value is changed with the change of the liquid level, and then the current or voltage signal in the circuit is changed to reach the purpose of measuring the oil level. Since the potentiometer is a touch-type anti-contact device, the resistance value will be changed for a long time, and the measurement error will be increased or even not used. Because of the large number of mechanical moving parts of the float structure, the wear and tear will be invalid for a long time;

2. Select the inductor coil as the base to view the component, use the floater to move the inductor coil, change the oscillation frequency of the oscillating circuit, and then measure the oil level through the frequency viewing circuit. The sensor structure produced by this method is messy, the debugging is troublesome, and the application cost is high. Difficult to be widely used;

3. The pressure sensor at the bottom of the fuel tank, through the output pressure value and oil density conversion, 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, which constitutes the measurement value negligence. (2) Since the height of the fuel tank is 1 meter or less, the selected pressure sensor range is 10kPa, 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 equipment can not be disassembled frequently at the bottom of the fuel tank, which affects the packing operation of the fuel tank; (4) Due to the temperature, the density of the oil will change, affecting the accuracy of the measured value;

4, the principle of the reed tubular 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 as follows: (1) The meta-device is easy to magnetize and has poor stability. (2) Due to the selection of on-off measurement, the product resolution is limited and the precision is low. (3) The float has more moving parts and is used for a long time. Poor reliability.