Liquid level switch system and liquid level measuring method

A liquid level switch system, comprising a transmitting probe, a receiving probe and a main unit;

• wherein the transmitting probe and the receiving probe are connected to the main unit by means of cables, respectively;
• the transmitting probe is installed at a warning position on an outer wall of a tank body, and the transmitting probe is configured to transmit an ultrasonic signal according to a control of the main unit;
• the transmitting probe comprises a piezoelectric plate and an inclined block;
• the inclined block is installed on the outer wall of the tank body, the piezoelectric plate is located on an inclined plane of the inclined block, and an incident angle of the ultrasonic signal entering a tank wall is changed through the inclined block;
• and the ultrasonic signal is transmitted into the tank wall to generate a longitudinal wave signal and a transverse wave signal with different refraction angles;
• the receiving probe is installed on the outer wall of the tank body, the receiving probe is separated from the transmitting probe by a preset distance;
• the longitudinal wave signal and the transverse wave signal with different refraction angles are received by the receiving probe after being reflected in the tank wall for many times;
• and the receiving probe is configured to send the detected longitudinal wave receiving signal and the detected transverse wave receiving signal to the main unit;
• the main unit is configured to determine whether a liquid level of the tank body reaches the warning position according to a signal strength difference between the longitudinal wave receiving signal and the transverse wave receiving signal.