CS201334B1 - Capacity scanner of the water level - Google Patents

Description

The invention relates to capacitive sensing of the water level in which the position of the water level is converted to the position of the dielectric liquid in the sensor.

Capacitance sensing is one of the most common methods of level measurement. However, when measuring the water level using conventional capacitive sensors a, it encounters the problem of biological and mechanical contamination of the sensor, which often completely distorts the measured data.

Contamination of the sensor can be prevented by sensing the movement of the clean liquid, the separation of which from the surrounding water is provided by a flexible vessel through which the walls of the clean liquid equalize the pressure of the surrounding water. Such an arrangement is described in French patent specification no. The disadvantage of this solution is the difficult technical implementation and the extreme demands placed on the material of which the flexible container is made, the failure of which leads to often inadmissible contamination of the surrounding water and whose rigidity reduces the sensitivity of the measurement.

The above-mentioned drawbacks are eliminated by the capacitive sensor according to the invention, in which the submerged container with the water inlet is a top-down separating tube connected at the bottom to the submerged container space by a connecting opening and at the top by a connecting tube to the sensor tube. An electrically insulated rod is attached to the axis of the sensor tube, which is, like the electrode sensor tube 334

In the immersion vessel and in the part of the separating tube, the separating liquid with a specific gravity is higher than the specific gravity of water.

There is a dielectric fluid above the separating liquid in the separation tube and the sensor tube.

Direct contact of the water with the separating liquid eliminates the most delicate part of the sensors used up to now - the flexible separating vessel, which simplifies the mechanical construction while increasing accuracy and reliability. When using a high density separating fluid, the sensitivity of the sensing part can be utilized and the entire sensor shortened.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are longitudinal sections of two embodiments of a capacitive water level sensor according to the invention. FIG. 1 shows an arrangement where the sensing portion is above the separating portion; FIG. 2 shows the sensing and separating portion side by side.

The capacitive water level sensor according to the invention (FIG. 1) consists of a separating and receiving part. The separating part consists of a submersible vessel 2 with a water inlet 3 and a separating tube 4 and a connecting opening 5. The sensing part consists of a sensor tube 7 in which the electrically insulated rod 8 is electrically insulated. The sensing and separating timer are connected by a connecting tube 6. In the immersion vessel 2, water 1 meets a separating liquid whose specific gravity is higher than the specific gravity of water. In the separating tube 4 above the level of the separating liquid 10 is a dielectric liquid 11, the level of which moves in the sensor part and determines the capacity of the rod 8 relative to the sensor tube 7. The conversion of the water level movement 1 to the movement of the dielectric fluid 11 in the sensor portion is determined by the specific weights of the separating liquid 10 and the dielectric liquid 11 and the cross-sectional ratios of the immersion vessel 2, the separating tube 4 and the sensor portion. The sensing portion may be above or adjacent the separating portion (FIG. 2). While placing the sensing part above the separating part makes the production and filling of the sensor easier than positioning the sensing and separating part side by side when the lowest demands are placed on the sensor filling because it is necessary to ensure that the space in the separating tube 4 located above the level of the separating liquid 1Ό as well as the entire connecting tube 6, which in this case is bent, were completely filled with dielectric liquid 11, in the latter case the sensor can be made relatively short and almost always ensure that even at minimum water level underwater, which reduces the temperature fluctuations to which the sensor is exposed and which affect the sensor life and measurement accuracy.

For the practical measurement of the water level, mercury is used as the separating liquid and silicone oil as the dielectric liquid. The immersion vessel 2 and the separating tube 6 must then be made of a mercury-resistant material. When using mercury as a separating liquid, the length of the separating tube 4 is less than 0.8 m per 10 m of water level swing. Since the entire sensor is almost always flooded with water, the upper end of the sensor portion is connected to the atmosphere by a pipe 6.

The capacitive water level sensor according to the invention is of general use in water

201 334 economy, energy and hydrology. Its simple design allows efficient mass production. The relatively small dimensions substantially reduce the installation costs, in particular compared to the float apparatus used hitherto.

Claims (1)

Capacitive water level sensor, characterized in that a separating pipe (4) connected to the lower part of the immersion vessel (2) with a water inlet (3) is connected from above to the immersion vessel (2) via a connecting opening (1). 5), acting in the upper part by means of a connecting tube (6) with a sensor tube (7) connected to the atmosphere by a tube (9), wherein an electrically insulated rod (8), which is like the tube (7) of the sensor connected by an electric conductor (12) to the evaluation circuit and in the immersion vessel (2) and in the part of the separating tube (4), the separating liquid (10) is higher than the specific gravity of water; (6) and the sensor tube (7) is above the level of the separating liquid (10) a dielectric liquid (11).