A self-calibrating capacitive liquid level sensor

Abstract

The invention relates to a self-calibrated capacitive liquid level sensor which comprises a measurement circuit module, a sensor housing, a sensor outer cylinder, a main probe, an auxiliary probe and a probe lead. The self-calibrated capacitive liquid level sensor is characterized in that the probe lead is of a double-layer shielding structure and is sequentially provided with the following six layers of structures from inside to outside: a core wire, a core wire insulating layer, an inner shielding layer, an inner shielding insulating layer, an outer shielding layer and an outer shielding insulating layer; the core wire, the inner shielding layer and the outer shielding layer of the probe lead and the main probe are all connected with the measurement circuit module; the measurement circuit module also comprises at least two voltage follower circuits. The self-calibrated capacitive liquid level sensor has the following benefits that a voltage with the same amplitude and the same phase with a probe excitation signal is generated by the follower circuits, so that measurement accuracy and stability of an instrument are effectively improved; by applying a voltage with the same amplitude and the same phase with the main probe to the outer shielding layer of the core wire, influence between the main probe and the auxiliary probe is insulated and measurement accuracy and long-term working stability of a product are greatly improved.

Description

technical field [0001] The invention relates to a capacitive sensor for measuring the liquid level height of a liquid medium, in particular, it can automatically detect the change of the dielectric constant of the measured medium, and the instrument can automatically correct the liquid level height measurement result to obtain an accurate liquid level height value. Background technique [0002] The method of determining the liquid level value by measuring the change of capacitance has been adopted a long time ago, and there are many liquid level gauge products based on this principle. This type of instrument generally adopts the principle of a coaxial capacitor. The central probe and the peripheral cylinder form a measuring chamber. When the chamber is empty, the capacitance is determined by the dielectric constant of the air, and it is filled with the liquid to be measured. Finally, the capacitance is determined by the dielectric constant of the liquid to be measured. The d...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a self-calibrating capacitive liquid level sensor with a unique lead wire structure and a drive circuit for the problems existing in the existing capacitive liquid level sensor with a self-contained medium compensation function, which is very good It effectively solves the problem of signal interference between the auxiliary probe and the main probe and the problem of measurement error caused by the change of the shape of the lead wire

Images