WO2022139652A1

WO2022139652A1 - A leakage detection mat

Info

Publication number: WO2022139652A1
Application number: PCT/SE2021/051166
Authority: WO
Inventors: Fredrik LINDELL; Alexander WHEELER
Original assignee: Elementric Ab
Priority date: 2020-12-22
Filing date: 2021-11-23
Publication date: 2022-06-30
Also published as: EP4267929A1

Abstract

The present disclosure relates to a leakage detection mat comprising at least one liquid detector (2). The mat comprises at least one fabric layer (1). The liquid detector (2) comprises at least two conductive threads (3) having high electrical conductivity embedded in the fabric layer (1) in such a way that the conductive threads (3) constitute at least one single electrical circuit. One end of each conductive thread (3) is connected to a control unit (4) via separate mounting elements (5). Each liquid detector (2) is arranged to provide a detection signal upon contact with liquid. The control unit (4) is arranged to generate an alarm signal based on said detection signal.

Description

A LEAKAGE DETECTION MAT

TECHNICAL FIELD

The present disclosure relates to leakage detection devices and systems.

BACKGROUND

Water installation is an essential part in buildings. Many appliances used in buildings require water for proper functioning, for example dishwashers. Water leakage caused by appliances malfunction may lead to a significant damage. To minimize the damage, it is essential that any leakage be detected early. Therefore, several leak detection mats are available in the prior art.

Patent application GB2365608A describes a device for detecting a water leak in a building, such as in a bathroom, which consists of a rectangular absorbent mat and a plurality of electrodes, which connect to an alarm.

Another example of a leak detector is presented in patent application EP0342905A2. The detector is made up of a mat for locating beneath the machine likely to leak.

SUMMARY

One object of the invention is to improve liquid leakage detection.

This has in accordance with the present disclosure been achieved by a leakage detection mat comprising at least one liquid detector. The mat comprises at least one fabric layer. The liquid detector comprises at least two conductive threads having high electrical conductivity embedded in the fabric layer in such a way that the conductive threads constitute at least one single electrical circuit. One end of each conductive thread is connected to a control unit via separate mounting elements. Each liquid detector is arranged to provide a detection signal upon contact with liquid, such as, e.g., water. The control unit is arranged to generate an alarm signal based on said detection signal. The mat is primarily intended for detection of water, but may be used to detect also other liquids.

The leakage detection mat has the advantage of providing a flexible and very thin liquid detection solution arranged to access narrow spaces. This further has the advantage of allowing the distance between the conductive threads to be selected so as to detect small quantities of liquid and generate an alarm signal. This further has the advantage of allowing leak detection to be performed with minimal power usage. A further advantage of the invention is its sensitivity, as the mat may detect as little as 0,05ml of liquid. The liquid detector comprising conductive threads allows the mat to be made extremely light and easy to transport.

It is to be understood that the expression "the conductive threads constitute at least one single electrical circuit" relates to the liquid detector's ability to form of a closed path upon exposure to liquid at said conductive threads. At an initial state the conductive threads are, for parts comprised in the fabric layer, not in direct contact with each other and may be considered part of an open electrical circuit. When water is absorbed in the fabric between the conductive threads the resistance decreases and a current starts to float between the conductive threads.

In some examples of the mat, the control unit comprises at least one alarm generator arranged to generate an alarm based on the alarm signal, and at least one energy source arranged to provide electric power to the mat.

This has the advantage of allowing the mat to generate an alarm, such as an auditory alarm, upon exposure to liquid.

In some examples of the mat, the mat comprises further at least one external liquid detector connected to the control unit. The external liquid detector comprises at least two conductive threads or wires constituting a single electrical circuit, wherein each one of the conductive threads have a coating layer made of fabric. The conductive threads or wires may be implemented as cotton covered copper wires, which are commercially available. Commercially available cotton covered copper wires have copper wires with a thickness of about 0.5-1.5 mm. Such cotton covered copper wires are suitably twisted together to ensure that they are in close proximity to each other along their length. It is possible to use conductive threads or wires that are thinner than 0.5 mm or thicker than 1.5 mm. In the case where conductive thread would be used, 2 or more parallel conductive threads would be sewn into the material, similar to how the mat is such that their mutual positions is well defined. The external liquid detector is arranged to provide a detection signal upon contact with liquid, i.e., when the liquid in the fabric lowers the resistance between the conductive threads. The fabric in the coating layer may be cotton. Cotton has a high water absorption. The fabric may be a woven cotton fabric. The function of the coating layers is to avoid direct contact between the conductive threads or between a conductive thread and a surrounding conductive surface. The coating layers may be separate coating layers. Alternatively, the coating layers may be connected with each other either by the coating layers being sewed together along their length or by the different coating layer being formed by the same piece of fabric in which two channels have been formed. By having the coating layers connected with each other it is ensured that the conductive threads are in proximity to each other, which is necessary for a sensitive detection.

The conductive threads may be twisted together. When the coating layers are not connected with each other twisting is a favourable method for ensuring the conductive threads to be in proximity to each other. By twisting the coated conductive threads, the distance between the conductive threads is ultimately limited only by the thickness of the fabric.

The external liquid detector has the advantage of allowing a long external liquid detector to be arranged around and along pipes and tubings. This further has the advantage of improving the ability to access narrow spaces for liquid leak detection.

In some examples of the mat, the control unit further comprises a microcontroller unit, a wireless communication module and an antenna. The microcontroller unit, the wireless communication module and the antenna are arranged to transmit alarm signals from the control unit.

This has the advantage of allowing one or more mats to be arranged at separate positions and have said mats transmit alarm signals to a remote central system. In some examples exposure to liquid causes a current flow, which activates a microcontroller unit comprised in the control unit, arranged to send the alarm signal via the communication module through wireless transmission to a user device or a cloud server.

In some examples of the mat, the at least two conductive threads of the liquid detector have been sewed into at least one of said at least one fabric layer.

This has the advantage of allowing a process with easy integration of conductive threads into the mat. This further has the advantage of allowing conductive threads to be arranged in close proximity, thereby improving detection sensitivity.

The conductive thread may be made from multiple strands, normally 2 or 3 of thread twisted together, which strands are impregnated with a conductive metal. The thread is designed to be sewn into fabric.

In some examples of the mat, comprises at least three stacked layers, wherein the at least two conductive threads of the liquid detector are comprised in an intermediate fabric layer.

This has the advantage of allowing conductive threads to be freely sewn into an intermediate fabric layer as fabric layers above and below cover the intermediate layer, thereby limiting the risk of undesired short-circuiting of the conductive threads. This further has the advantage of allowing stacks of fabric layer with different properties to be created.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 and Fig. 3 show plan views of embodiments of the leakage detection mats without control unit.

Fig. 2, Fig. 4 and Fig. 5 show plan views of embodiments of the leakage detection mats with the control units attached.

Fig. 6 and Fig. 7 show detailed views on control unit.

Fig. 8a-c depict a leakage detection mat comprising three stacked layers with conductive threads comprised in the middle layer.

Fig. 9 depicts a leak detection mat with an external liquid detector arranged around a liquid Pipe. DETAILED DESCRIPTION

Throughout the figures, same reference numerals refer to same parts, concepts, and/or elements. Consequently, what will be said regarding a reference numeral in one figure applies equally well to the same reference numeral in other figures unless explicitly stated otherwise.

The first embodiment of the invention, as illustrated in Fig. 1 and 3 is a leakage detection mat comprising one liquid detector. The mat comprises one fabric layer 1 and the internal liquid detector 2 comprising two copper conductive threads 3 embedded in the fabric layer 1. One end of each conductive thread 3 is connected to a control unit 4 via two separate electrically conductive clips used as mounting element 5. The control unit 4 is detachably connected to the mat layer 1 using said mounting elements 5. It comprises one energy source 6 and an alarm generator 7. The energy source provides energy for the electrical circuit constituted by the conductive threads 3.

In some examples, the distance between conductive threads 3 of the internal liquid detector 2 is between 5 to 20 mm. In some of these examples the distance between conductive threads 3 is between is 5 to 10 mm.

The second embodiment of the invention is illustrated in Figs. 2 and 4. It is a leakage detection mat comprising two liquid detectors 2 and 8. The internal liquid detector 2 is made of two conductive threads 3 comprising silver and embedded in the cotton layer 1. One end of each conductive thread 3 is connected to a control unit 4 via two separate electrically conductive clips used as mounting element 5. The control unit 4 is detachably connected to the mat layer 1 using said mounting elements 5. The external liquid detector 8 is also connected to the control unit 4. The external liquid detector 8 comprises two silver conductive threads or wires 9 twisted together and constituting a single electrical circuit. The conductive threads or wires 9 have an insulating coating layer 10 made of cotton or paper. The energy source provides energy for the two electrical circuits constituted by the conductive threads 3 and 9. The control unit 4 further comprises a microcontroller unit 11, a wireless communication module 12 and an antenna 13. In this case, the communication module 12 is a Wi-Fi module. The depicted external liquid detector 8 is not necessarily to scale. Typically, the external liquid detector 8 is configured to extend beyond the mat layer 1.

In some examples each liquid detector 2,8 is arranged to generate a detection signal upon contact with liquid, wherein the detection signal is generated based on a resistance between at least two conductive threads 3,9. In some examples, the detection signal is generated based on a current running through closed circuit formed by at least two conductive threads 3, 9. In some of these examples, the detection signal is generated based on a predetermined current threshold and/or a predetermined resistance threshold.

The third embodiment of the invention is illustrated in Fig. 5. It is a leakage detection mat comprising two liquid detectors 2 and 8. The internal liquid detector 2 is made of five conductive threads 3 comprising silver and embedded in the cotton layer 1 and constituting 4 separate electrical circuits. Conductive threads 3 are connected to a control unit 4 via five electrically conductive clips used as mounting element 5.

Fig. 6 and 7 depicts the control unit. The control unit 4 comprises at least one energy source 6 providing electricity to the circuit and at least one alarm generator 7. The control unit 4 is detachably connected to the mat layer using mounting elements 5. The energy source provides energy for all four circuits. The control unit 4 further comprises a microcontroller unit 11, a wireless communication module 12 and an antenna 13. In this case, the communication module 12 is a Bluetooth module and a radio module.

Fig. 8a-c depict a mat comprising three stacked layers 1,1', 1” with conductive threads 3 comprised in the middle layer 1'.

Fig. 8a depicts three stacked layers 1, 1', 1” with conductive threads 3 embedded inside the middle layer 1'. Fig. 8a represents an example where the conductive threads 3 are isolated from direct contact with the other layers 1,1”.

Fig. 8b-c depicts three stacked layers 1,1', 1” comprising conductive threads 3, wherein the conductive threads 3 have been sewed threw the middle layer 1'. Fig. 8b represents a viewed from a direction parallel to the orientation of the conductive threads, and fig. 8c represents a cross-sectional view from a direction orthogonal to the orientation of the conductive threads. Fig. 8b-c represent an example where the conductive threads 3 have been sewed through the middle layer 1' and comes into contact with the first 1 and third layer 1”.

In fig. 8b-c the eye symbols aims to represent the relationship between the views of the three stacked layers 1, 1', 1", wherein both viewing directions lay in the plane of the stacked layers. The eye symbol in fig. 8b represent a viewing direction parallel to the threads general direction into the stacked layers (into the plane of the figure, not from below the layers), while the eye symbol in fig. 8c represents a viewing direction that corresponds to looking at the three stacked layers in fig. 8b from the right side.

In some examples the mat comprises at least three stacked layers 1,1', 1”, and the conductive threads 3 have been sewed threw at least one intermediate layer 1'.

In some examples the mat comprises at least three stacked layers 1,1', 1”, and the conductive threads 3 are comprised in an intermediate layer 1'.

Depending on the type of stitch used, the conductive thread may be arranged differently from what is shown in Fig 8c. Sewing conductive threads 3 into the middle layer 1' may allow said threads to be arranged close together without risk of being in direct contact, thereby increasing the liquid leakage sensitivity of the leak detection mat.

In some examples, at least two conductive threads 3 have been sewed into at least one of said stacked layers 1, 1', and 1''.

In some examples, at least one of the conductive threads 9 of the external liquid detector 8 constitute a fibre, which is impregnated with a metal, such as silver.

In some examples, the mat comprises three stacked layers 1, 1', 1”, wherein the at least two conductive threads 3 have been sewed into the middle fabric layer 1'.

In some examples the three stacked layers 1, 1', 1" each comprise fabric.

In some examples the three stacked layers 1, 1', 1" are arranged to at least in some regions of the mat be movable in relation to each other.

Fig. 9 depicts a leak detection mat with its external liquid detector arranged around a liquid pipe. The example leak detection mat comprises one fabric layer 1 comprising an internal liquid detector 2, and further comprises an external liquid detector 8 and a control unit 4. The control unit 4 is arranged at the fabric layer 1, and the liquid detectors 2, 8, are connected to the control unit 4.

Fig. 9 relates to a use example of the leak detection mat wherein the fabric layer 1 comprising the internal liquid detector 2 is arranged on a surface at which leakages are to be detected, and the external liquid detector 8 is arranged around a liquid pipe 20 at or below a potentially leaking part of the liquid pipe 20.

It is to be understood that the external liquid detector 8 may be arranged to path several revolutions around a liquid pipe 20 or an object at which leakage is to be detected. In some examples, the external liquid detector 8 is arranged releasably attached to an object at which leakage is to be detected by pathing the external liquid detector 8 around said object. As the water leakage is detected by a lowered resistance, the leakage detection is very sensitive. This is in contrast to prior art techniques such as that described in KR20030003536A, which relies on the leaking water to break a thin conductive wire configured around a water pipe. Breakage of the conductive thread requires a comparatively large water flow.

The invention disclosed herein is a leakage detection mat comprising at least one liquid detector. The essence of this invention is that the mat comprises at least one fabric layer 1. The liquid detector 2 comprises at least two conductive threads 3 having high electrical conductivity. The conductive threads 3 are embedded in the fabric layer 1 in such a way that they constitute at least one single electrical circuit. One end of each conductive thread 3 is connected to a control unit 4 via separate mounting element 5. The control unit 4 is detachably connected to the mat layer 1 using mounting elements 5. The control unit 4 comprises at least one energy source 6 providing electricity to the circuit and at least one alarm generator 7.

The leakage detection mat may also comprise at least one external liquid detector 8 connected to the control unit 4. The external liquid detector 8 comprises at least two conductive threads 9 constituting a single electrical circuit. The conductive threads 9 have a coating layer 10 made of fabric. The fabric in the coating layer 10 be wowen/unwoven cotton. The conductive threads 9 may be sewed onto the coating layer 10, such that their mutual positions are well defined. Preferably, the mounting elements 5 are electrically conductive clips. The conductive threads or wires 3 and 9 may comprise silver, copper, tin or nickel.

Preferably, the control unit 4 further comprises a microcontroller unit 11, a wireless communication module 12 and an antenna 13. The wireless communication module 12 may be a Wi-Fi module, a Bluetooth module or a radio module.

Preferable the fabric is permeable to water and it may be a cotton or a paper.

When a liquid, such as water, appears on the mat it creates a bridge between the two conductive threads, and the current provided by the control unit will flow completing the circuit. It then activates the alarm generator within the circuit causing the audible alarm. It is also possible that the current flow could activate the microcontroller unit, which will send the alarm signal via the communication module to the user device or the cloud.

An advantage of the invention is its sensitivity. It may detect as little as 0,05ml of liquid by using the combination of fabric and conductive threads. It is also extremely light and easy to transport, as it is foldable. It allows detection of leakage as soon as possible by mounting of the external detector directly around the pipes. The microcontroller unit triggers the alarm through wireless transmission, in result the user is able to act faster, even if the user is not home.

In some examples, the leakage detection mat comprises three stacked layers of fabric: the top layer, the middle layer and the bottom layer.

The middle layer is where the conductive thread have been sewed with an automatic embroidery machine. Two sets of thread are used when using an automatic sewing machine, one thread for the top and one thread for the bottom. On each stich, the top thread is pushed through the fabric and the bottom thread hooks it. In some examples, conductive thread is used on the top and normal thread is used on the bottom.

The fabric material is substantially 100% cotton that has had minimal chemical treatment. Cotton fabrics will vary and will resist water if chemically treated, similar to other fabrics. Cotton acts as an excellent absorber of water, allowing conductivity of the water to be measured. The bottom layer covers the bottom part of the middle layer and may provide a good finish. The bottom layer also acts as an insulator, such that the conductive threads comprised in the middle layer are not short-circuited if the mat is place on top of a conducting surface. This layer may be arranged to not be transparent and may comprise the same bulk material as the middle layer.

The top layer may be the same material used in sports clothing. The top layer may have many perforations in it. The material used in sports clothing is excellent at letting water pass through it, rather than soaking it up. The top layer may be used to protect the conductive thread from being accidentally torn and/or may perform as an insulator against conditions of the external environment, such as heat or mechanical wear. Without the top layer, the conductive thread may risk breaking due to mechanical contact with the external environment. Also, without the top and/or bottom layer the conductive threads may come in contact with each other if the mat is folded locally.

In some examples the control unit is attach to the fabric we use rivets. In some examples, a printed circuit board comprised in the control unit is attached to the fabric. Attachment utilizing rivets provides quick and effective attachment.

The leakage detection mat may be configured to operate for extended periods of time while utilizing a limited energy source, such as operating several years on a cr2032 battery. In some embodiments closing the circuit of a liquid detector, as caused by a leakage detection event, turns on the control unit. In such an embodiment, the energy consumption prior to closing the circuit may be kept very low or effectively zero.

In some embodiments the control unit provide a predetermined low current and/or a predetermined low voltage for the liquid detector. Performing electrolysis of water at the liquid detectors may adversely affects the sensitivity during subsequent leakage detections.

In some examples, the control unit comprises filters arranged to mitigate electromagnetic interference (EMI) in the leakage detection mat. In some examples, at least one EMI filter is connected to at least one liquid detector.

A significant part of the leakage detection mat comprises fabric, which may allow the leakage detection mat to be produced easily and cheaply with mass production techniques, such as commonly used embroidery machines. The leakage detection mat is at least partially foldable and lightweight allowing for easy and inexpensive transport and shipping.

In some examples, the external liquid detector 8 comprises two conductive threads, wherein said threads comprise two pieces of single core copper wire, wherein each copper wire is shielded using cotton, and the two shielded copper wires are twisted together. The twisted wires are arranged to, when water soaks into the cotton between the two copper wires, a circuit is closed and a signal is allowed to pass through which we can be detected at the control unit. Utilizing single core copper wire typically allows the twisted wires to be arranged around pipes or other objects so that the twisted wire maintain its shape and thus keeps in place.

In some examples the leakage detection mat is configured to, when a part of the liquid detectors 2, 8 is exposed to at least 0.05 ml liquid, at least two conductive threads are short circuited by said liquid, whereby the liquid exposure event is detected based on a change in current, potential, resistance and/or impedance of a circuit comprising said two conductive threads.

Claims

1. A leakage detection mat comprising at least one liquid detector (2), wherein the mat comprises at least one fabric layer (1), wherein the liquid detector (2) comprises at least two conductive threads (3) having high electrical conductivity embedded in the fabric layer (1) in such a way that the conductive threads (3) constitute at least one single electrical circuit, wherein one end of each conductive thread (3) is connected to a control unit (4) via separate mounting elements (5), wherein each liquid detector (2) is arranged to provide a detection signal upon contact with liquid, and wherein the control unit (4) is arranged to generate an alarm signal based on said detection signal.

2. The mat according to claim 1, wherein the control unit (4) comprises at least one alarm generator (7) arranged to generate an alarm based on the alarm signal, and at least one energy source (6) arranged to provide electric power to the mat.

3. The mat according to claim 1 or 2, wherein the control unit is detachably connected to the at least one fabric layer (1) using mounting elements (5).

4. The mat according to any preceding claims, wherein the mat comprises further at least one external liquid detector (8) connected to the control unit (4), wherein the external liquid detector (8) comprises at least two conductive threads or wires (9) constituting a single electrical circuit, wherein each one of the conductive threads (9) have a coating layer (10) made of fabric, and wherein the external liquid detector (8) is arranged to provide a detection signal upon contact with liquid.

5. The mat according to claim 4, wherein the conductive threads or wires (9) of the external liquid detector are wires which are twisted together.

6. The mat according to any preceding claims, wherein the mounting elements (5) comprise electrically conductive clips.

7. The mat according to any preceding claims, wherein the conductive threads (3,9) comprise silver, copper, tin and/or nickel.

8. The mat according to any preceding claims, wherein the control unit (4) further comprises a microcontroller unit (11), a wireless communication module (12) and an antenna (13), wherein the microcontroller unit (11), the wireless communication module (12) and the antenna (13) are arranged to transmit alarm signals from the control unit (4).

9. The mat according to claim 8, wherein the wireless communication module (12) is a Wi-Fi module, a Bluetooth module or a radio module.

10. The mat according to any preceding claims, wherein the fabric is permeable to water.

11. The mat according to claim 10, wherein the fabric is cotton and/or paper.

12. The mat according to any preceding claims, wherein the at least two conductive threads (3) have been sewed into at least one of said fabric layer (1).

13. The mat according to any preceding claims, wherein at least one of the conductive threads (3, 9) constitute a fibre in a multi-fibre thread.

14. The mat according to any preceding claims, wherein the at least one fabric layer (1) comprises a woven cotton fabric.

15. The mat according to any preceding claims, comprising at least three stacked layers (1, 1', 1”), wherein the at least two conductive threads (3) of the liquid detector (2) are comprised in an intermediate fabric layer (1').

16. The mat according to claim 15, comprising three stacked layers (1, 1', 1”), wherein the at least two conductive threads (3) of the liquid detector (2) have been sewed into the middle fabric layer (1').