DE102007032250B3 - Liquid i.e. water, leakage detecting device i.e. humidity sensor, for e.g. washing machine, has conductor paths present on side of surface unit, where one side of surface unit is flat while another side of surface unit is rough - Google Patents

Abstract

The device has conductor paths (2) e.g. comb, that are not in electrical contact with each other and spaced from each other. The paths are present on a side of an electrically non-conductive, flexible surface unit (1) e.g. fleece and fabric. An electrical voltage is applied between the conductor paths, and an electrical resistance is measured between the conductor paths when a water drop (3) is present on the surface unit. A side of the surface unit is flat while another side of the surface unit is rough, where the surface unit is formed from absorbent material. An independent claim is also included for a method for manufacturing a device for detecting liquid leakage.

Description

The The invention relates to a device for detecting liquid leaks according to the preamble of claim 1; the invention further relates a method for producing such a device.

humidity sensors serve for monitoring and Detection of leaking fluids, For example, leaks in shower trays, bathtubs, whirlpools as well as in the most diverse liquid containers or Tanks for example in the chemical industry. Further fields of application are conceivable, for example as a moisture sensor for incontinence.

The Functional principle of such humidity sensors is that between two electrodes change the ohmic resistance is measured. Is located between the two electrodes an electrically conductive liquid, the ohmic resistance decreases from infinity to a measurable value.

The EP 0 342 905 A2 shows a leak detector, especially for the domestic sector and especially for washing machines of the type specified. The leak detector consists of a flexible mat of a plastic material. On this mat strip conductors are arranged, which engage in a rake-like manner. An electrical voltage is applied to the printed conductors via connections. As soon as there is liquid on the mat, the conductors are short-circuited, thus reducing the ohmic resistance. This will then be displayed on the display device.

The DE 200 17 863 U1 shows a moisture and leak monitoring. For this purpose, a surface structure is provided consisting of an absorbent surface material in the form of a nonwoven. This sheet material is equipped with electrically conductive strips which mesh with each other in a rake-like manner. The non-woven material is completely flat and can be glued on any surface with commercially available adhesive. It is also possible that the sheet material is incorporated in composite materials.

The DE 43 16 436 C2 shows a composite foil for the electrical detection of a leak. A Zwichenschicht of a nonwoven material is provided on its upper side with mutually parallel upper conductor tracks and on its underside with a group of mutually parallel lower conductor tracks. The groups of these tracks are arranged at a right angle to each other.

The DE 10 2004 041 497 A1 , the DE 10 2004 031 099 B4 , the DE 103 49 963 A1 as well as the DE 37 32 825 C2 Finally, coating processes in which films or the like are coated from roll to roll are shown.

Of the Invention is based on the object, a device for detecting of fluid leaks to create the type specified, which works for a reliable and even the smallest fluid leaks detected and which is inexpensive to produce for another; Farther is a method for producing such a device be created.

The technical solution is marked according to the device by the features in the characterizing part of claim 1.

Thereby a device is provided for detecting liquid leaks, by means of which a large-scale monitoring possible is. The basic idea of the invention is that on an electric non-conductive, large area element Anzuord NEN conductors, which in their entirety a large-scale conductor pattern define. Here are between two or more ends of the tracks provided electrical contacts. As conductor material comes Aluminum, silver, copper, an aluminum-copper alloy, chromium, titanium, Tin, stainless steel etc. in question. In the dry state, so if no fluid leak is to be detected measures between the electrical contacts of the tracks an infinite huge electrical resistance. If moisture reaches the surface element, arises between two adjacent tracks an electrically conductive Connection. One measures then a finite ohmic resistance. This triggered current flow can with a signaling device, for example with a signal light or with an acoustic signal. The flexibility of the surface element has the advantage that it even with non-planar surface structures the surface element be easily installed under adaptation to this surface structure can. By the surface element from an absorbent Material exists, this has the advantage that impinging drops of liquid a leak gradually spread. When the fluid area has spread so that the two tracks of a conductor pair in contact with the liquid arrive, the detection takes place. The surface element looks different surface structures in front. On the smooth side while the conductors are applied, which proves to be favorable in terms of manufacturing costs. The rough back however, the moisture absorbs better.

The development according to claim 2 has the advantage that even small liquid drops (and thus small liquid leaks) can be detected. Because by the interconnects of a pair of interconnects run substantially parallel to each other and the distance is chosen correspondingly low, the distance to be bridged between the two tracks is relatively low. If the surface element is covered over its almost entire surface with these parallel conductor track pairs, liquid drops that strike any point of the surface element are detected very quickly.

The Training according to claim 3 beats different waveforms of the tracks before. It comes here primarily interlocking conductor combs, parallel Meander as well concentric spirals in question. Other patterns are conceivable.

at the surface element it is according to the training in claim 4 preferably to a nonwoven, a fabric or a Foil. A preferred material is a nonwoven as a flexible Carrier. Because the fleece has the advantage that it absorbs moisture easily. Nonwoven materials include, for example, PETP, PP, PE, PA, viscose or mixtures thereof.

When technical solution are procedurally the Features of claim 5 proposed.

The The basic principle is that on the surface element the conductor tracks in the roll-to-roll coating process in vacuum applied, in particular vapor-deposited. This represents a simple one Method to apply the traces to the sheet material. After the conductor tracks have been applied to the surface element, this can be tailored and separated accordingly.

embodiments a device according to the invention for detecting liquid leaks will be described below with reference to the drawings. In these shows:

1 a first embodiment of a device in which the conductor tracks are formed as interlocking combs;

2 a longitudinal section through the surface element in 1 in an enlarged view;

3 a second embodiment in which the conductor tracks are applied in the form of meanders on the surface element;

4 a third embodiment in which the conductor tracks are applied in the form of concentric spirals on the surface element.

1 shows a first embodiment of a device for detecting liquid leaks.

The device has a flexible surface element 1 in the form of a fleece. This has a smooth top and a rough bottom.

On the smooth top are printed conductors 2 firmly applied. These tracks 2 form two groups, which mesh together like a comb. An electrical voltage is applied to these two interconnect groups.

The operation is as follows:
In the dry state you measure between the tracks 2 of the two conductor groups an infinitely large electrical resistance.

But if a liquid, for example in the form of a drop of water 3 on the surface element 1 , so arises between two adjacent tracks 2 (namely where the liquid impinges) an electrically conductive connection. This measures a finite resistance. By this circuit can then be a signaling device 4 , in particular an optical or an acoustic signaling device 4 to be activated.

In the second embodiment in 3 are the tracks 2 a conductor track pair also spaced in parallel. This interconnect pair has the course of a meander. From the basic mode of operation, this embodiment corresponds to the embodiment in FIG 1 ,

The third embodiment in 4 Finally, also has a pair of interconnects whose tracks 2 are spaced parallel to each other. The course of the tracks 2 is in the form of concentric spirals.

Other courses of the interconnect pair are conceivable.

1

surface element

2

conductor path

3

Waterdrop

4

signaling device

Claims (5)

Device for detecting liquid leaks, with an electrically non-conductive, flexible surface element ( 1 ), on one side of which at least two, spaced apart and not in electrical contact with each other standing electrical conductor in the form of conductor tracks ( 2 ), wherein between the electrical conductors, an electrical voltage is applied and wherein the electrical resistance between the electrical conductors is measured, characterized in that the surface element ( 1 ) consists of an absorbent material and that that side of the surface element ( 1 ), on which the tracks ( 2 ), while the other side is rougher in comparison. Device according to the preceding claim, characterized in that the printed conductors ( 2 ) of a conductor track pair, between which the voltage is applied, substantially parallel to each other. Apparatus according to claim 2, characterized in that the conductor tracks ( 2 ) in the form of interlocking rakes or in the form of meanders or in the form of spirals. Device according to one of the preceding claims, characterized in that the surface element ( 1 ) is a nonwoven, a fabric or a film. Method for producing a device for detecting liquid leaks according to one of the preceding device claims, characterized in that the printed conductors ( 2 ) in a roll-to-roll coating process on the surface element ( 1 ) are applied.