WO2008142470A1

WO2008142470A1 - Electronic device used to detect and signal water leaks in hydraulic circuits installed in buildings

Info

Publication number: WO2008142470A1
Application number: PCT/IB2007/001343
Authority: WO
Inventors: Maria Adela Dumbravian
Original assignee: Hambleden Consultant Group Lp
Priority date: 2007-05-18
Filing date: 2007-05-18
Publication date: 2008-11-27

Abstract

The present invention relates to an electronic device used to monitor a branch of a hydraulic circuit in order to detect heavy or micro water leaks; it being provided that, in case of water leaks, the said device is designed to automatically interrupt the water delivery to the branch and send an acoustic and/or luminous alarm signal.

Description

Electronic device used to detect and signal water leaks in hydraulic circuits installed in buildings.

This patent application relates to an electronic device used to detect and signal water leaks in water delivery and distribution systems installed in buildings.

The device of the invention, which seems not to have any antecedents in the technical field, was devised to protect spaces with water distribution systems against severe damages caused by heavy water leaks in the installation.

Another purpose of the device of the invention is to remedy the possible presence of micro leaks that, although incapable of causing damages to the building, involve water waste; in particular, reference is made to the small leaks that may occur, including for long time, in faucets that have not been perfectly closed in places with infrequent users.

The said purposes have been achieved by the device of the invention, which is provided with an electronic unit with timer that controls the functions of a solenoid valve, a flow sensor and a mechanical pressure switch installed in a branch of the hydraulic circuit to be monitored.

In particular, the cooperation between the flow sensor, the solenoid valve and the electronic unit has been studied to detect and signal heavy water leaks produced in the hydraulic circuit downstream the point where the device of the invention is installed.

If a heavy water leak is detected, the control unit sends a command to the solenoid valve to stop the water flow in the corresponding branch of the hydraulic circuit.

The cooperation between the pressure switch, the solenoid valve and the electronic unit allows to detect and signal micro leaks; also in this case, the electronic unit automatically sends a command to the solenoid valve to stop the micro leak. For major clarity, the description of the device of the invention continues with reference to the enclosed drawings, which only have an illustrative, not limiting value, whereby figure 1 is a diagrammatic view of the structure of the device of the invention and its application mode in a branch of the hydraulic circuit.

With reference to the said figure, the device of the invention, which can be installed in any branch (D) of a hydraulic circuit, is composed of an electronic unit with timer (1) that is interfaced with a flow sensor (2), a pressure switch (3) and a solenoid valve (4). In particular, the three elements (2, 3, 4) are installed in sequence in the branch (D) to be monitored; it being provided that the flow sensor (2) is installed downstream and the solenoid valve (4) is installed upstream, while the pressure switch (3) is installed in intermediate position.

As mentioned earlier, the flow sensor (2) is used to detect heavy water leaks.

More precisely, the flow sensor (2) basically consists in a rotor splined to a permanent magnet and is driven into rotation in case of a water flow of minimum 1.7 l/min.

The magnetic flow produced by the rotation of the said rotor excites a Hall sensor that informs the electronic unit (1) of the presence and volume of the water flow in the branch (D).

In order to take advantage of the said information, the user of the device of the invention must set a maximum delivery time of water in the branch (D) in the timer of the electronic unit (1 ), which is suitably provided with keypad and display.

The expression "maximum delivery time" refers to a time longer than the time considered necessary to perform the ordinary functions associated with water consumption, according to the specific habits of the users of the hydraulic circuit to be monitored. Preferably, the maximum delivery time must be set by the user in a time range included between 5 and 90 minutes, with 1 -minute steps.

For example: if the user generally has a 10-minute shower, he will set 12/15 minutes as the maximum delivery time of the branch (D) to be monitored; in this way, the user will have enough time to have a shower without exceeding the maximum delivery time.

The setting of the said maximum delivery time is essential for the operation of the device of the invention.

In fact, because of the cooperation with the sensor (2), the electronic unit (1 ) immediately detects the presence of a heavy water flow in the branch (D) and draws different conclusions according to whether the water flow occurs within or after the said maximum delivery time. In the first case, the electronic unit (1 ) is programmed in such a way that the presence of a water flow in the branch (D) to be monitored is considered normal, since the said water flow is generated by the users of the hydraulic circuit when opening the faucets.

On the contrary, when the electronic unit (1) is informed of the presence of a heavy water flow after the said maximum delivery time (when all faucets should be closed), the unit (1) assumes the presence of a uncontrolled water leak in the hydraulic circuit downstream the branch (D).

However, this assumption may be untrue; for example, users may keep water faucets open beyond the limits of the said maximum delivery time, departing from their consolidated habits.

In this perspective, the device of the invention is programmed in such a way to repeat the said measurement at least three times in case of an anomalous water flow in the branch (D).

If the repeated control cycles determine the presence of a water flow in the branch (D) to be monitored, the flow is considered as really "anomalous" by the electronic unit (1 ).

In this case, the system switches from the pre-alarm status to a real alarm status.

Consequently, the electronic unit (1) sends a command to the solenoid valve (4) to interrupt the water flow towards the hydraulic circuit supplied by the branch (D) to be monitored.

The electronic unit (1) simultaneously generates an acoustic and/or luminous alarm signal, preferably using the display of the electronic unit (1).

This description continues with a detailed description of the entire procedure, including the repeated control cycles.

When the flow sensor (2) detects the presence of a water flow after the maximum delivery time in the branch (D) to be monitored, the electronic unit (1 ) closes the solenoid valve (4) installed in the branch (D) for a time period (or range) preferably limited to 10" only; simultaneously, the electronic unit (1 ) sets a pre-alarm status for the device of the invention.

Such a short closing time of the solenoid valve (4) is set to allow the electronic unit (1) to determine whether it is a real water leak or a water flow caused by the fact that the user is using water from an ordinary faucet beyond the maximum delivery time.

In fact, if the flow detected in the branch (D) is caused by the fact that the user keeps the faucet open beyond the said maximum delivery time, and the faucet is closed by the user within the 10" time period, no water flow is detected in the branch (D) to be monitored after the solenoid valve (4) is reopened.

The absence of water flow allows the electronic unit (1 ) to consider the said anomalous situation as an "authorised" water delivery, although beyond the maximum delivery time, and rules out the possibility of an uncontrolled leak, since the latter would have resulted in a water flow in the branch (D) after the said 10" time range.

Nevertheless, the user may decide to keep the faucet open beyond the first 10" time range. This means that the presence of a water flow in the branch (D) would be detected after the solenoid valve (4) is re-opened.

Now, the electronic unit (1) starts a new identical operating cycle, closing the solenoid valve (4) again for another 10" time, reserving the right to evaluate whether the water flow in the branch (D) is interrupted or is still present when the solenoid valve (4) is re-opened.

If the water flow is still present, the electronic unit (1 ) starts a third identical operating cycle of the solenoid valve (4). If a water flow is still detected in the branch (D) when the solenoid valve (4) is opened for the third time, the electronic unit (1 ) is "authorised" to consider that the persistent water flow is caused by a real heavy water leak.

In fact, it is highly improbable that the persistence of the water flow in the branch (D) is still considered as a request for water delivery made by the user after the maximum delivery time.

This is because the user is well aware of the maximum delivery time that is set and of the inconveniences that may originate from a similar request made after the maximum delivery time; therefore, it is highly improbable that the user continues on keeping the faucet open for a total time equal to the three control time periods.

Moreover, assuming that the user has forgotten the presence of the device of the invention or the duration of the maximum delivery time, the interruption of the normal water delivery in the faucet - as a consequence of the temporary closing of the solenoid valve (4) - would remind the user about the presence of the device and make him immediately close the faucet.

The most important thing is that, as soon as the electronic unit (1 ) detects that the water flow in the branch (D) is caused by a heavy water leak, as illustrated above, the same unit (1 ) sends a command to permanently close the solenoid valve (4), thus causing the permanent interruption of the water flow towards the hydraulic circuit supplied by the branch (D) to be monitored.

Of course, the permanent interruption of the water flow prevents the damages that could be caused by an uncontrolled heavy water leak, and give maintenance operators the possibility to repair the installation.

When the water leak has been repaired, the solenoid valve (4) can be reopened normally, by means of the keypad of the electronic unit (1 ) or of a remote infrared control.

This description continues with the illustration of the operation of the device of the invention when the solenoid valve (4) detects the total absence of water flow in the branch (D) to be monitored, when it is reopened after the interruption of the solenoid valve (4). In this case, the electronic unit (1) does not detect any uncontrolled water leaks and therefore removes the pre-alarm status, maintaining the solenoid valve (4) open and resetting the counter of the maximum delivery time. Moreover, it must be noted that the device of the invention is capable of detecting significant supplies of water that are occasionally requested by the user of the hydraulic circuit that may, on the contrary, deceive the electronic unit (1).

If the flow sensor (2) detects an anomalous delivery increase in the branch (D) to be monitored, for example with minimum 30" duration and flow equal or higher than 5 l/min., based on this specific piece of information, the electronic unit (1 ) resets the counter of the maximum delivery time, giving the user of the hydraulic circuit an "extraordinary" extension of the water delivery time. However, as mentioned above, the device of the invention is also capable of detecting and signalling micro water leaks, that is to say leaks with flow lower than 1.7 l/min, which may not be detected by the flow sensor (2). To this end, the electronic unit (1) cooperates with the mechanical pressure switch (3) installed downstream the solenoid valve (4), which is suitably set with an actuation threshold value of approximately 1 bar.

In this case the operative logic principle used by the device of the invention is as follows.

When the device is operated to detect micro water leaks, the

"detection index" is the pressure loss that is produced in a hydraulic circuit with delivery lower than 1.7 l/min after closing the solenoid valve in the section of branch (D) downstream the solenoid valve, where the pressure switch (3) is installed.

In fact, such a pressure drop is the consequence of the loss of elastic energy previously accumulated by the hydraulic circuit, perhaps due to the presence of air sacks; such a loss is determined in case of an uncontrolled water leak through a small hole or in case of dripping from a defective or loose faucet. More precisely, the electronic unit (1) detects a micro water leak in the presence of a pressure drop to a value lower than 1 bar in a conventional "micro leak" time set by means of programming or self-learning.

Nevertheless, in order to be sure that the pressure drop downstream the solenoid valve (4) is effectively due to a micro water leak, the device of the invention is operated according to a specific logic principle.

According to the said logics, the electronic unit (1 ) can detect the pressure drop only after two hours have elapsed since the last water delivery in the branch (D) to be monitored. In cooperation with the timer, the electronic unit (1) can autonomously measure the aforementioned time range (minimum two hours), considering as starting time the moment when the flow sensor (2) informs the interruption of the water flow in the branch (D).

Once two hours have elapsed and the water flow in the branch (D) to be monitored has not been restored, the electronic unit (1) closes the solenoid valve (4) and checks the status of the mechanical pressure switch (3) in the aforementioned "micro leak" time.

If, during the conventional time range, the electronic unit (1) detects that the pressure switch (3) remains in the ON logic status, due to the presence of a pressure higher than 1 bar in the branch (D) to be monitored, the presence of a micro leak can be ruled out.

For this reason the electronic unit (1) reopens the solenoid valve (4) and performs the same check at two-hour time intervals.

If, on the contrary, the pressure switch (3) detects a pressure drop in the branch (D) to be monitored to a value equal or lower than 1 bar, which corresponds to the OFF logic status of the pressure switch (3), the electronic unit (1 ) is set in the pre-alarm status and performs the following operative cycle: a) opening of the solenoid valve (4) for a preset 5-minute time period; b) closing of the solenoid valve (4) and check of the pressure switch (3) for the preset "micro leak" time period; c1) if, during the "micro leak" time period, the pressure in the branch (D) to be monitored remains above 1 bar, the electronic unit (1) considers the test as passed (no micro leaks) and cancels the alarm status; c2) if, during the "micro leak" time period, the pressure is lower than 1 bar, the electronic unit (1 ) activates the execution of steps a) and b) for four consecutive times; d) if, a pressure lower than 1 bar is detected during the fifth check, the electronic unit (1) switches from the pre-alarm to the alarm status, which permanently closes the solenoid valve (4) and generates an acoustic signal and an error message on the display. Now the user can identify the specific reason for the micro leak and remedy it.

Once the problem has been solved, the user will reopen the solenoid valve (4) by means of the keypad of the electronic unit (1) or by means of a remote infrared control. Finally, it must be noted that the device of the invention is also capable of managing the lack of water supply in the branch (D) to be monitored, as well as the lack of power supply of the electronic unit (1 ).

The following conditions occur in case of lack of water supply: the flow sensor (2) remains still, the mechanical pressure switch (3) remains OFF (due to the presence of a pressure lower than 1 bar) and the solenoid valve

(4) remains open.

In such a case, the check process for micro leaks is immediately aborted due to the detection of the OFF status of the mechanical pressure switch (3). In order to neutralise the negative effect of a possible interruption of the power supply of the electronic unit (1 ), the electronic unit (1) is provided with a buffer memory system that allows to restore the status of the solenoid valve (4).

This is done for safety reasons, since the solenoid valve (4) is of bistable type and therefore is already provided with a mechanical memory.

Claims

1 ) Device used to detect and signal water leaks in hydraulic circuits, characterised by the fact that it is provided with an electronic unit with timer (1 ) interfaced with a solenoid valve (4) and a flow sensor (2) set to detect a predefined flow value, both being installed in sequence, from upstream downstream, in the same branch (D) of the hydraulic circuit to be monitored; it being provided that:

- the flow sensor (2) comprises means designed to inform the electronic unit (1 ) about the presence of a water flow equal or higher than the preset value in the branch (D) to be monitored; - the electronic unit (1), whose timer is set with a predefined "maximum delivery time", is provided with a software application designed to send a command to close the solenoid valve (4) when it detects the presence of the flow with the predefined flow in the branch (D) beyond the predefined "maximum delivery time". 2) Device as claimed in claim 1, characterised by the fact that the means used by the flow sensor (2) to inform the electronic unit (1 ) about the presence of a water flow equal or higher than the preset value in the branch (D) consist in a Hall sensor excited by the permanent magnet suitably associated with the rotor of the sensor (2). 3) Device as claimed in claim 1 , characterised by the fact that the electronic unit (1) generates an acoustic and/or luminous alarm signal when the solenoid valve (4) is closed.

4) Device as claimed in claim 1 , characterised by the fact that, before permanently closing the solenoid valve (4), the electronic unit (1) temporarily and repeatedly closes the solenoid valve (4) for predefined short time periods, if it has been informed by the flow sensor (2), after each temporary opening of the solenoid valve (4), about the presence of a water flow higher than the predefined flow for a time longer than the aforementioned "maximum delivery time" in the branch (D) to be monitored; it being provided that, if values with flow or duration higher than the predefined values are detected during one of the checks of the flow in the branch (D), the electronic unit (1 ) permanently closes the solenoid valve (4), while, if the flow with values higher than the predefined flow and duration values is no longer detected in the branch (D), the electronic unit (1 ) does not send the command to permanently close the solenoid valve (4).

5) Device as claimed in one or more of above claims, characterised by the fact that, when the electronic unit (1) is informed by the flow sensor (2) about the presence of a water flow higher than the predefined value set in the sensor (2) and detects that the said "anomalous" flow is present for a time longer than the "maximum delivery time", the electronic unit (1 ) resets the timer for the calculation of the said "maximum delivery time".

6) Device as claimed in one or more of above claims, characterised by the fact that the electronic unit (1) is also interfaced with a pressure switch (3) installed in the same branch (D) to be monitored downstream the solenoid valve (4), which is set with a predefined pressure value, conventionally defined as "detection index"; it being provided that, after the "conventional micro leak time" set on the timer of the electronic unit (1 ) has elapsed, as measured by the flow sensor (2), between two contiguous water deliveries in the branch (D) to be monitored, the electronic unit (1) closes the solenoid valve (4) and interrogates the pressure switch (3) on the pressure value detected in the same branch (D); it also being provided that, if the electronic unit (1) is informed about a pressure drop higher than the aforementioned "detection index", the electronic unit (1) maintains the solenoid valve (4) permanently closed. 7) Device as claimed in claim 6, characterised by the fact that, after the electronic unit (1) interrogates the pressure switch (3) and is informed about a pressure drop equal or lower than the "detection index", the electronic unit (1) reopens the solenoid valve (4) for a predefined time period set in the timer of the electronic unit (1) and activates one or more new checks of the pressure in the branch (D) after a predefined time limit set in the timer of the electronic unit (1 ); it being provided that the electronic unit (1 ) closes the solenoid valve (4) permanently if, during the last check, it detects a pressure value lower than the "detection index" in the branch (D). 8) Device as claimed in one or more of above claims, characterised by the fact that the predefined flow value set in the flow sensor (2) is equal to 1.7/litres per second. 9) Device as claimed in one or more of above claims, characterised by the fact that the "maximum delivery time" is included in a time range from 5 to 90 minutes.

10) Device as claimed in claim 4, characterised by the fact that the predefined time periods for the temporary closing of the solenoid valve (4) are equal to 10 seconds.

11) Device as claimed in one or more of above claims, characterised by the fact that the "detection index" set in the pressure switch (3) is equal to 1 bar.

12) Device as claimed in claim 7, characterised by the fact that the solenoid valve (4) remains open for 5 minutes before each check.