Patent Description:
The present invention relates to a monitoring system for liquid level detection in a tank.

In various technical areas, it is necessary to detect the level of liquid in a tank.

For example, in flush cisterns for sanitary appliances, the need arises, especially in order to avoid waste and reduce water consumption, to accurately control the amount of water in the cistern, so as to detect any leaks, monitor consumption, etc..

Similar problems are found in other industries and applications, and with different liquids. Patent application <CIT> discloses examples of monitoring systems to detect the level of water in a well.

In many cases, placing level sensors inside a tank can be difficult, due to accessibility issues, tank size, etc..

A particularly relevant problem is the need to keep a level sensor inserted in a tank calibrated. In general, level sensors require periodic calibration to be fully efficient and reliable. But calibration requires an operator.

The present invention set out to resolve the problems highlighted above; in particular, one purpose of the invention is to provide a monitoring system for liquid level detection in a tank that can be easily and economically adapted to various applications and installation situations.

It is a further purpose of the invention to provide a universal intelligent system that, regardless of the specific installation, is able to adapt and self-adjust to the installation conditions without the need for operator intervention.

The present invention therefore relates to a monitoring system for liquid level detection in a tank as defined in essential terms in the appended claim <NUM> and, in its additional characters, in the dependent claims.

In essence, the system of the invention combines (at least) one pressure sensor and two optical sensors. The pressure sensor measures the pressure at the bottom of the tank where the system is installed (preferably through a sealed pipe). The optical sensors measure the presence of liquid in two predetermined spatial positions, for example corresponding to a maximum filling level of the tank and an empty tank level.

In this way, the pressure sensor receives indications of two known reference conditions. This ensures that the pressure sensor is constantly calibrated via the optical sensors each time a tank emptying and filling cycle occurs, reducing the risk of needing recalibration.

With this architecture, the pressure sensor, designed to measure the liquid level in the tank, is completely autonomous and does not require periodic manual calibration and provides level measurements with high accuracy (with deviations +/- <NUM>).

The system of the invention is thereby suitable for equipping a wide variety of tanks, particularly subject to filling and emptying cycles such as, for example, flushing cisterns for sanitary appliances.

The system of the invention may also be configured to transmit a variety of additional information to the user, such as the presence of operating problems, history of filling and emptying events, and so forth.

Advantageously, then, all the parts of the system are provided with an IP67 equivalent degree of protection, which makes the system more resistant and durable than other solutions of the prior art.

In addition, the system can be integrated into an articulated support body so that it can be inserted into a tank even with a small access opening, as is the case for example (but not only) with sanitary appliance flush cisterns. The system of the invention thus allows a universal installation, in all types of flushing cisterns (built-in, external, ceramic, etc.), being also easily installed and removable from any type of tank.

All the materials in the system can then be selected to have high durability.

Further characteristics and advantages of the present invention will become clear from the following description of a non-limiting example of an embodiment made with reference to the appended drawings, wherein:.

In <FIG> reference numeral <NUM> globally denotes a monitoring system for liquid level detection in a tank <NUM>.

The tank <NUM> may be of various types and intended for various applications. For example, but not necessarily, the tank <NUM> is a flush cistern of a sanitary appliance.

The tank <NUM> has a bottom wall <NUM> and contains a variable amount of liquid (e.g., water, but also other liquid), which reaches a variable level in the tank <NUM>.

With reference also to <FIG> and <FIG>, the system <NUM> comprises a support body <NUM>; a pipe <NUM> supported by the support body <NUM> and extending along an axis C; at least one pressure sensor <NUM>; a pair of optical sensors <NUM>, <NUM> positioned spaced apart from each other on the support body <NUM>.

The support body <NUM> comprises a top portion <NUM> and a bottom portion <NUM> positioned at respective axially opposite ends of the support body <NUM>, and a bar <NUM> extending between the portions <NUM>, <NUM>.

Preferably, the bar <NUM> comprises two sectors 59a, 59b articulated to each other by a hinge <NUM> (shown in detail in <FIG>), so that the bar <NUM> can fold by tilting the two sectors 59a, 59b relative to each other. Thus, if necessary, the articulated bar <NUM> allows for easy insertion of the system <NUM> through an opening in the tank <NUM>.

In particular, the hinge <NUM> comprises a pin <NUM> engaging a rotation seat <NUM>, on respective sectors 59a, 59b; and a stop member <NUM> engaging an abutment seat <NUM>, formed on respective sectors 59a, 59b to limit the rotation of the sectors 59a, 59b relative to one another.

Advantageously, the two sectors 59a, 59b are also separable from each other by releasing the stop member <NUM> from the abutment seat <NUM> and pulling the pin <NUM> out of the rotation seat <NUM>.

For example, the pipe <NUM> is a flexible tube, open at the lower end and above directly connected to the pressure sensor <NUM>.

In particular, the pipe <NUM> has opposite open axial ends 67a, 67b and extends between the portions <NUM>, <NUM> to which it is attached, for example, by respective fittings <NUM> inserted into the axial ends 67a, 67b. Optionally, the pipe <NUM> is also attached to the bar <NUM> by snap-on elements <NUM>.

The opposite axial ends 67a, 67b communicate with an entrance <NUM> formed in the portion <NUM> and, respectively, with an interior chamber <NUM> of the portion <NUM>.

The chamber <NUM> houses the pressure sensor <NUM> and a control unit <NUM> (e.g., a circuit board) controlling the pressure sensor <NUM> and the optical sensors <NUM>, <NUM>. Advantageously, the chamber <NUM> is liquid-tight sealed so as to have at least an IP67 equivalent degree of protection.

The pressure sensor <NUM> is located at the upper axial end 67a of the pipe <NUM> and closes the axial end 67a; the pipe <NUM> is fluid-tight sealed, being open only at the lower axial end 67b.

The pressure sensor <NUM> is configured to detect the atmospheric pressure and the pressure acting on the pressure sensor <NUM> through the pipe <NUM>, i.e., the pressure of the fluid column inside the pipe <NUM> (air present in the pipe <NUM>, pushed by the liquid rising in the pipe <NUM>), to determine the liquid level inside the tank <NUM>.

For example, the pressure sensor <NUM> has a flexible membrane that is sensitive to changes in pressure acting on the membrane and an integrated microprocessor detecting the displacements of the membrane due to pressure changes and translates them into signals that are sent to the control unit <NUM>.

In a preferred embodiment, the pressure sensor <NUM> is a differential pressure sensor, configured so as to measure atmospheric pressure and the pressure of the fluid column in the pipe <NUM> and to calculate the difference between the two measured pressure values to calculate the level of liquid in the tank <NUM>.

In one variation, the sensor assembly <NUM> comprises a pair of pressure sensors <NUM> configured to measure the pressure acting on the sensors <NUM> to calculate the liquid level in the tank <NUM>. In particular, each sensor <NUM> has a flexible membrane that is sensitive to changes in pressure acting on the membrane and an integrated microprocessor detecting displacements of the membrane due to pressure changes and translates them into signals that are sent to the control unit <NUM>. A first sensor <NUM> detects atmospheric pressure, being positioned above the filling level of the tank <NUM> with the membrane exposed to atmospheric air; a second sensor <NUM> detects pressure at the bottom of the tank <NUM> and is immersed in the liquid contained in the tank <NUM>, or is positioned at the upper end 67a of the pipe <NUM> in contact with the column of air inside the pipe <NUM>.

Advantageously, both sensors <NUM> are in any case positioned in the upper portion <NUM> of the sensor assembly <NUM>, above the filling level of the tank <NUM>, and the pressure at the bottom of the tank <NUM> is detected, as described above, through the fluid column in the pipe <NUM> directly in contact with one of the sensors <NUM>.

In this case also, the sensors <NUM> are configured to calculate the liquid level in the tank <NUM> by means of differential pressure values detected by the first sensor <NUM>, exposed to atmospheric pressure, and the second sensor <NUM>, in contact with the column of air contained in the pipe <NUM>.

The support body <NUM> is equipped with a hook <NUM>, or other fastener, for securing the support body <NUM> and thus the system <NUM> as a whole inside the tank <NUM>. For example, the hook <NUM> extends from a side wall of the portion <NUM> and engages a corresponding seat (not shown) formed inside the tank <NUM>.

The optical sensors <NUM>, <NUM> are positioned on the support body <NUM> axially spaced apart from each other. For example, the optical sensors <NUM>, <NUM> are positioned on the portion <NUM> and the portion <NUM>, respectively.

The optical sensors <NUM>, <NUM> face downwards, i.e., towards the bottom wall <NUM> of the tank <NUM>, so as to detect the presence of a liquid level below them.

For example, the optical sensors <NUM>, <NUM> are on-off type optical sensors emitting infrared radiation to detect the presence of liquid at the respective position (height).

The optical sensors <NUM>, <NUM> are connected to the control unit <NUM>, for example, via cables <NUM>. In particular, the lower optical sensor <NUM> is connected to the control unit <NUM> by a cable <NUM> that is optionally guided by a plurality of fastenings <NUM> located along the bar <NUM>.

It is understood that the pressure sensor <NUM> and/or the optical sensors <NUM>, <NUM> may also be connected to the control unit <NUM> wirelessly.

The control unit <NUM> is then advantageously equipped with a wireless device for exchanging (receiving and transmitting) data with the outside world, for example with a user interface device and/or a remote server, which stores and processes the data sent by the control unit <NUM>.

Advantageously, to adapt the system <NUM> to different tanks <NUM> of various sizes (in particular, having different depths or heights), the system <NUM> has a common upper portion (formed by the portion <NUM> and the first sector 59a of the bar <NUM>), and a lower portion (formed by the portion <NUM> and the sector 59b) which is made depending on the tank <NUM> it is to be fitted to and in particular with a sector 59b of varying lengths to adapt to different tanks <NUM>, in order to keep the lower optical sensor <NUM> as close as possible to the bottom wall <NUM> of the tank <NUM>.

In general, the support body <NUM> is shaped so that the optical sensor <NUM> is positioned near the bottom wall <NUM> of the tank <NUM>; while the optical sensor <NUM> and the pressure sensor <NUM> are positioned above the normal maximum filling level of the tank <NUM> (<FIG>).

In use, the liquid level in the tank <NUM> is measured by the system <NUM>: the liquid in the tank <NUM> also enters the pipe <NUM> through the inlet <NUM> and compresses the air column inside the tube <NUM>. The pressure sensor <NUM> measures the pressure of the fluid column (column of air) inside the pipe <NUM> and thus the pressure at the bottom of the tank <NUM>, from which the liquid level in the tank <NUM> is derived.

The optical sensors <NUM>, <NUM> detect the presence of liquid at two predetermined spatial positions and thereby allow the calibration of the pressure sensor <NUM> in two known reference operating conditions.

The combined use of the pressure sensor <NUM> and the two optical sensors <NUM>, <NUM> allows the system <NUM> to accurately detect the liquid level and self-calibrate without external intervention.

In particular, the optical sensors <NUM>, <NUM> detect whether the tank <NUM> is full or empty, i.e., whether the tank <NUM> contains liquid at two predetermined reference levels: if the upper optical sensor <NUM> detects liquid at its position, the tank <NUM> is full; if the optical sensor <NUM> detects no liquid below it, the tank <NUM> is empty.

The optical sensors <NUM>, <NUM> communicate to the control unit <NUM> when the tank <NUM> is full or empty, and the control unit <NUM> may accordingly calibrate the pressure sensor <NUM> whenever necessary (e.g., after each tank emptying and filling cycle). The pressure sensor <NUM> is thus constantly calibrated, without the need for operator calibration.

In this way, the sensor assembly <NUM> is completely self-contained and does not require periodic manual calibration.

The user can read off the level values at any time with high accuracy, with an indicative tolerance of +/- <NUM>.

The system <NUM> can thus operate with high durability and provide data on any problems and malfunctions, such as leaks, overfilling, operating problems, overflow events, and provide consumption measurements, performance delivered, and so on.

Claim 1:
A monitoring system (<NUM>) for liquid level detection in a tank (<NUM>), comprising a support body (<NUM>) supporting at least one pressure sensor (<NUM>) configured for measuring a liquid level in the tank (<NUM>), and a control unit (<NUM>) connected to the pressure sensor (<NUM>); the system (<NUM>) being characterized by comprising a pair of optical sensors (<NUM>, <NUM>) positioned spaced apart from each other on the support body (<NUM>) and connected to the control unit (<NUM>); and in that the control unit (<NUM>) is configured so as to calibrate the pressure sensor (<NUM>) according to data provided by the optical sensors (<NUM>, <NUM>).