FR2778459A1 - Device for detection of a leak from a domestic water supply be detection of any movement in the water meter indicator - Google Patents

Abstract

The device comprises optical means (4,5) for detection of any movement of the indicator of a meter indicator (6) mounted on the outside of a water meter. The optical means such as an LED and a phototransistor detector are arranged so that the indicator is within their optical path. Means (12) are provided for analysis of the meter movement to determine over a period of time if a leak is present.

Description

The present invention relates to a device for detecting a

  leak in a fluid distribution network and, more particularly, in such a device designed for a network comprising an apparatus for measuring the flow rate of the fluid distributed by this network, this apparatus being equipped with a mobile display device for its activity, set in motion when the network delivers fluid. More particularly still, the invention relates to such a device designed to monitor a

  domestic distribution network of running water.

  These latter networks are normally equipped with a device commonly called a "water meter", placed upstream of the network to measure the volume of water admitted into the network, and therefore debited by it, for billing purposes. of this volume of water by the business of

  distribution of water supplying said network.

  These domestic networks are commonly subject to overconsumption of water due to leaks, especially in the networks served. These leaks are often located in buried or invisible pipes and are therefore difficult to locate. They can then exist for long periods of time before being detected. This results in losses which can be very large and costly for the company's subscribers.

of distribution.

  To rapidly detect such leaks, devices for monitoring the activity of the measuring device, a flow meter, and for detecting abnormal activity of this device, that is to say, have been designed. activity that manifests itself when no consumer of water, sink, bathtub, swimming pool, sprinkler, etc. is put into service. The detection is based on the fact that a leakage rate is generally low but continuous over time while the flow rate of a consumer is high but of a duration which generally does not exceed a few hours. We then deduce the presence or absence of water leaks in the network, the absence or the presence respectively, of an inactivity of the water meter for at least a few minutes, inside a time interval of several hours, for example 12 hours. A total absence of inactivity of the meter during such a time interval is in fact normally indicative of the presence of a continuous component in the water flow, due to a leak in the network. When such a leak is detected, the monitoring device issues an alert signal, or commands the safety of the

  network by closing valves, for example.

  The known devices for this purpose have the disadvantage of being able to operate only with water meters of particular type, incorporating a magnetic sensor for example, to deliver a signal representative of an activity of the meter, that is to say -to say a flow of water by it, to means for processing this information, suitable for diagnosing the presence of a leak in the monitored network. These devices are therefore not adaptable to networks equipped with conventional water meters, not provided with such a sensor, which is the case for the vast majority of current domestic networks, except to provide for the replacement of the

  water meter, which is expensive.

  The object of the present invention is precisely to provide a device for detecting a leak in a distribution network for a fluid, in particular water for domestic use, which does not have these drawbacks and which, in particular, can be installed. in any network equipped with a conventional meter, devoid of

activity sensor.

  The present invention also aims to achieve such a device which is inexpensive to manufacture and

  therefore accessible to the greatest number.

  These objects of the invention are achieved, as well as

  others which will appear on reading the description

  which follows, with a device for detecting a leak in a fluid distribution network, comprising an apparatus for measuring the flow rate of the fluid distributed by said network, said apparatus being equipped with a mobile display device for its activity, set in motion when the network delivers fluid, this device being remarkable in that it comprises optical means for detecting the movement of said member mounted opposite it, outside said device, to emit a signal representative of the movements of the organ, and means for analyzing the temporal changes of said signal in order to deduce therefrom

  the possible existence of leaks in the network.

  As will be seen in detail below, the use of optical means for detecting the movements of the movable member, and therefore the activity of the measuring device, makes it possible to simply mount these means on this device, without requiring any modification thereof, which may additionally be of any of many currently known types. The device according to the invention is thus of universal application, production and installation inexpensive in accordance

  to the aims of the present invention.

  According to a characteristic of the present invention, the movable member comprises at least one range having a gradient of optical density in reflection and in that the optical means are sensitive to the movements of said range with gradient of optical density to transmit said signal. The optical means comprise a radiation emitter arranged to illuminate said movable member and a receiver sensitive to the light reflected by said illuminated movable member, arranged to deliver said signal, the level thereof varying when said density gradient range passes through a predetermined position. Other characteristics and advantages of the present invention will appear on reading the

  description which follows and on examination of the attached drawing

  in which: - Figure 1 is a schematic representation of the device according to the invention, - Figure 2 shows the dial of a conventional water meter and the location of part of the device according to the invention on this dial , - Figure 3 is a functional diagram of the device according to the invention, - Figure 4 shows waveform graphs of signals, useful for explaining the operation of the device according to the invention, and - Figure 5 represents the flowchart of a program executed by the device according to the invention for diagnosing the presence or absence of leaks

in the monitored network.

  Referring to Figure 1 of the accompanying drawing o there is shown schematically the device according to the invention, which appears externally as formed of a small plate 1 connected to a housing

  control 2 by an electric cable 3.

  The plate 1 is equipped with optical detection means constituted by a radiation emitter 4 and a receiver 5 of a fraction of this radiation, reflected by a mobile object, as will be seen below, the emitter and the receiver being placed side by side to one another

as shown in figure 1.

  By way of illustrative and nonlimiting example, the transmitter 4 can be constituted by a diode of the LED type emitting infrared radiation and the receiver by a phototransistor sensitive to the radiation of said diode. The plate 1 is dimensioned to be able to be fixed, for example by means of a double-sided adhesive, opposite a movable member 6 visible through a glass pane protecting the display dial of a conventional water meter 7 , as shown in broken lines in FIG. 2. Such a dial commonly comprises a plurality of rotating disks 81, 82, 83, 84 bearing numbers which make it possible to read the volume of water which has passed through the meter, for example in view billing of this volume, as we saw above. It also includes the movable member 6, which, in the embodiment shown by way of illustration and not limitation only, takes the form of a rotating disc coated with an index 9 substantially radial, optically detaching from the bottom of the disc by strong contrast, or density gradient

optics in reflection.

  As soon as the network (not shown) located downstream of the counter 7 delivers water, this member 6 is rotated by a mechanism which couples it to a turbine (not shown) through which the circulating water passes, this turbine driving also 8 discs via

  suitable transmission mechanisms.

  According to the present invention, the diode 4 is placed relative to the disc 6 so that the index 9 comes to cut the brush of infrared radiation emitted by the diode when this disc is rotated by a flow of water in the network. The phototransitor 5 is itself arranged relative to the disc so as to be sensitive to the fraction of the radiation from the diode which is reflected by the latter. The output voltage of the phototransistor is then an image of the reflectance of the range of the disc 6 which is lit by the diode 4 and can therefore be used to detect a variation in this reflectance due to the passage of the index finger 9 in the radiation brush. emitted by the diode 4, and therefore an active state of the water meter 7. We now refer to the functional diagram of Figure 3 which illustrates in more detail the means

  electronics incorporated in the device according to the invention.

  This figure shows the control unit 2, the diode 4 and the phototransistor 5 carried by the plate 1,

disc 6 and index 9.

  The control unit comprises means for controlling the supply of the light-emitting diode 4, means for shaping 11 the output signal of the phototransistor 5, means for analyzing signals constituted by a microcontroller 12 supplied by the output signal conforming means 11, and means

  power supply 13 of the aforementioned means.

  By way of illustrative and nonlimiting example only, the means 10 may be constituted by an adaptation resistor or an oscillator, the means 11 by an amplifier mounted as a comparator so as to deliver a square signal such as those illustrated in the graphs of Figure 4, and the means 13 by an electric battery 14

  associated with a voltage regulator 15.

  It was thus possible to construct a device according to the invention using for the diode 4, an infrared light-emitting diode type SFH 421-P with surface mounting from the company SIEMENS AG, for the phototransistor 5, a phototransistor of the type 2440-002 with mounting on the surface of the company HONEYWELL, for the shaping means 11, an amplifier of the LM 324 type, for the voltage regulator, the programmable regulator ADM 666 from the company Analog Devices and for the microcontroller, that referenced

SAB 80C515 at SIEMENS AG.

  There is also, on the control unit 2, a light-emitting diode 16 emitting radiation in the visible range and a switch 17 with manual control making it possible to connect this diode to the terminals of the phototransistor, for a purpose which will be described later. The operation of the device according to the invention is now explained, in conjunction with the examination of the graphs.

A, B, C, in Figure 4.

  When the diode 4 is supplied and the disc 6 rotates due to the fact that the counter 7 is crossed by a stream of water, the passage of the index finger 9, dark in color, black for example, in the brush of emitted infrared radiation by the diode 4, makes fall the quantity of light reflected by the disc towards the phototransistor 5 at a low level, whereas when this brush falls on the light background of the disc the quantity of reflected light is higher. After conformation of the output signal from the phototransistor illuminated by a variable quantity of light, the signal which leaves the means 11 takes the rectangular shape represented in FIG. 4, varying between a logic level 0 and a logic level 1 corresponding to the reflectance of the background. disc 6 and index 9 respectively, or vice versa, depending on the type of

phototransistor 5.

  The frequency of the rectangular pulses thus sent to the microcontroller 12 is a function of the speed of rotation of the disk 6. FIG. 4 shows the pulse trains formed for three different flow values, ie an average flow (graph A) , a flow

  low (graph B), high throughput (graph C).

  It is clear that a zero flow is then characterized by maintaining the signal at one of its two logical levels and that, during the entire time interval where the flow remains zero, there is no switching of the level of the signal between these two levels, since the water meter 7 X is then inactive and that consequently the disc 6 remains stationary. The microcontroller 12 is used to monitor the temporal changes in the signal delivered by the signal conformation means 11, so as to draw a diagnosis therefrom as to the possible existence of a leak in the water distribution network located downstream of the measuring device 7 of the water flow absorbed by this network. To do this, one can choose a microcontroller incorporating a counter 18 controlled by the rising edges, for example, pulses of the output signal of the shaping means 11. Alternatively, the counter could be

  outside the microcontroller and connected to it.

  The microcontroller 12 is duly programmed to execute a diagnostic strategy such as that illustrated by the flow diagram of FIG. 5, given by way of example only. In general, as indicated above, this strategy consists in detecting the absence or the presence of a period of inactivity of the sensor 7, of a predetermined duration, within an interval of predetermined time, to diagnose the presence or absence, respectively, of a leak in the

network monitored.

  As noted above, in a domestic water system, water consumers,

  sink, bathtub, swimming pool, watering device, etc ...

  rarely work more than a few hours at a stretch.

  On a 24-hour time horizon, for example, there are almost always times when all consumers of water are turned off. In the absence of a leak in the network, the water meter 7 then remains completely inactive during these moments, and no change in state of the counter 18 of the microcontroller 12 is observed. On the contrary, the presence of a leak , generally of low flow, causes a slow and continuous switching of the meter 18, even when all the water consumers, at higher flow, are inactive. It is the detection of such a slow and continuous switching (causing changes of state of the counter 18) which is significant of the presence of a leak in the network. If therefore during a test of change of state of the counter 18 of a relatively short duration, of a few minutes for example, no change of state of the counter is observed while the presence of a leak would certainly have caused at least one, it can be confidently diagnosed that, during this test, no water consumer was activated and that no leak was present in the monitored household network. It is then unnecessary to repeat this test quickly because the probability of such a leak appearing immediately after the test is low. We can then put the device in standby to minimize energy consumption, and therefore

  to spare the battery 14 which supplies it.

  This putting the device into standby mode can be effected by an appropriate control of the regulator 15, for example, and for a predetermined time interval, fixed by the discharge of a capacitor in an RC circuit by

example, as is well known.

  Alternatively, the device according to the invention could be equipped with an integrated circuit 19 called "electronic calendar" such as that referenced PCF 8583 in the catalogs of the company Philips. Such a calendar can be programmed so as to control the activation or the standby of the device, by an appropriate command of the current regulator. The use of such a calendar makes it possible to control an activation of the device at a time of the day when the water consumers are normally inactive, around 2 am for example. In the absence of a leak, the test is then very brief and the device is quickly put back into standby state, which is favorable from the point of view of saving electrical energy. This can increase the life of the

stack 14.

  Reference is now made to the flow diagram of FIG. 5 to describe the strategy described above, in an implementation given by way of illustrative example and not

restrictive only.

  After an initialization step 20, the microcontroller reads the state of the counter 18 in step 21, so as to be able to detect possible subsequent changes in this state. In step 22, the microcontroller performs a state change test of a short predetermined duration, for example 5 minutes. If no change of state is detected during this period, it means that no water consumer is activated and that the domestic network is not affected by any leak. We then go to step 29 where the device is put in standby state to save battery energy, for a fairly long period of time.

long, for example 12 hours.

  If at least one change of state is detected in step 22, this change can be attributed either to the activation of a water consumer connected to the monitored network, or to a leak. To remove this indeterminacy, the change of state test is repeated, possibly for the next four hours (steps 23 to 26). If then a total inactivity of the flow measurement device 7 is noted for at least 5 minutes, the

device in standby state.

  Otherwise, and assuming that no water consumer is likely to operate for four hours in a row (this duration can also be modified to adapt the device to local conditions of water use network), it must be concluded that the total absence of inactivity of the water meter 7 is due to a network leak (step 27). A signal 1!

  alarm is then issued (step 28) by the microcontroller.

  As a variant, this signal can activate a solenoid valve for closing the mains supply, to limit the

volume of water lost by the leak.

  The proper functioning of the device according to the invention is conditioned by a precise tracking of the plate 1 which carries the transmitter 4 and the receiver 5, above the index 9 of the disc 6. To obtain this tracking specifies, when placing the plate 1 on the window of the dial of the water meter 7, connect the light-emitting diode 16 (see FIG. 3) to the terminals of the receiver 5 by pressing the switch 17. We do then slide the plate 1 on the glass of the dial of the meter, after having established a water flow through it, until obtaining a flashing light emission of maximum intensity of the diode 16, significant of what the phototransistor is well centered on the axis of the radiation brush reflected by the disc

6 and by the index 9 which it carries.

  Advantageously, the microcontroller is equipped with means for testing the state of the battery 14 and for emitting an alert signal when the voltage delivered by the latter

  falls below a predetermined low level.

  Of course, the invention is not limited to the embodiment described and shown which has been given only by way of example. Thus the invention is applicable to the monitoring of a fluid distribution network

  any liquid or gas, not just water.

  Likewise, the invention is applicable to networks comprising slightly different water meters to that shown, in which the rotary disc 6 with index 9 is replaced by a disc of the stroboscopic type for example, or also by a non-rotating member. , but mobile, oscillating for example, provided that the mobility of this member can be detected by optical means. The latter can themselves be constituted by any photosensitive device produced in integrated circuit rather than composed of discrete elements for example, capable of

  detecting a movement of the mobile organ being monitored.

  It now appears that the invention makes it possible to achieve the aims pursued, namely to realize a device for detecting leaks in a fluid distribution network, easily adaptable in particular to domestic water distribution networks, and which can be realized in current low manufacturing costs

  volume of electronic equipment.

Claims (12)

  1. Device for detecting a leak in a fluid distribution network, comprising a device for measuring (7) the flow rate of the fluid distributed by said network, said device being equipped with a movable member (6) of display of its activity, set in motion when the network delivers fluid, characterized in that it comprises optical means (4,5) for detecting the movement of said member (6) mounted opposite it, at the outside of said device (7), for emitting a signal representative of the movements of the member (6), and of means of analysis (12) of the temporal evolutions of said signal to deduce therefrom the possible existence of a leak in the network.   2. Device according to claim 1, characterized in that said movable member (6) comprises at least one area (9) having an optical density gradient in reflection and in that said optical means (4,5) are sensitive to movement of said beach (9) to transmit said signal.   3. Device according to claim 2, characterized in that said optical means (4,5) comprise a radiation emitter (4) arranged to illuminate said movable member (6) and a receiver (5) sensitive to the light reflected by the illuminated movable member (6), arranged to deliver said signal, the level thereof varying when said range (9) with a gradient of   density goes into a predetermined position.   4. Device according to claim 3, characterized in that said transmitter (4) and said receiver (5) are mounted on a plate (1) comprising means for fixing the latter on the wall of the measuring device (7), opposite the organ   mobile (6) for displaying the activity of the device.   5. Device according to claim 4, characterized in that said transmitter (4) and said receiver (5) are electrically connected to a control unit (2) comprising said means of analysis (12) of the signal delivered by the receiver (5). 6. Device according to claim 5, characterized in that said housing (2) comprises a) control means (10) of the transmitter, b) shaping means (11) of the output signal of the receiver (5 ), c) a microcontroller (12) powered by the shaped signal and constituting said analysis means and d) electrical supply means (13) of these means (10,11,12).   7. Device according to any one of   claims 1 to 6, characterized in that said   analysis means (12) are sensitive to the absence or the presence of a period of inactivity of said measuring device (7), of a predetermined duration, within a predetermined time interval, to diagnose the presence or absence, respectively, of leaks in said network.   8. Device according to any one of   Claims 1 to 7, characterized in that it comprises   means (19) for selectively activating said detection means (4,5) and said analysis means (12) at a   when the network does not normally deliver fluid.   9. Device according to any one of   Claims 1 to 8, characterized in that it comprises   means for putting the device on standby for a predetermined duration, when the analysis means (12) diagnose an absence of leak in the monitored network. 10. Device according to any one of   claims 5 to 9, characterized in that it comprises   a light emitting diode (16) for emitting a visible light signal when the receiver (5) delivers an electric current, and means (17) for selectively and temporarily connecting said diode (16) in parallel to said receiver (5) during mounting of the plate (1) on the measuring device (7). 11. Device according to any one of   claims 6 to 10, characterized in that said   electrical supply means (13) comprise an electric battery (14) and in that means are provided for testing the state of the battery and issuing an alert signal when the output voltage of the battery (14) falls   below a predetermined level.   12. Device according to any one of   previous claims, characterized in that said   analysis means (12) control, upon detection of a leak, the activation of alarm and / or activation means network security monitored.