JP4780970B2 - Leak sensor - Google Patents

Description

  The present invention relates to a water leakage sensor used in a water leakage detection system.

  As one of the countermeasures for disasters in a residence, office, hospital, warehouse, etc., various water leak detection systems for immediately detecting unexpected water leaks and floods and promptly informing residents and managers are provided. In general, a water leakage detection system includes a water leakage sensor that detects the presence of liquid using a medium such as electricity, sound, and light, and a water leakage detector that performs a notification operation such as generation of an alarm based on the liquid detection signal of the water leakage sensor. . Here, an electric water leakage sensor detects passive continuity between a pair of electrodes separated from each other as the presence of liquid (ie, leakage water), and corresponds to an increase or decrease in the amount of liquid interposed between the electrodes. The electric resistance value of the water leakage sensor itself that fluctuates in this way is detected and processed by the water leakage detector as a liquid sensing signal. Therefore, in the water leakage detection system including the electric water leakage sensor, it is assumed that the liquid to be sensed has conductivity.

  The electric leak sensor in the leak detection system has a liquid sensing ability (that is, sensitivity) determined mainly depending on the configuration of the electrode. Conventionally, depending on the application of the leak detection system (laying environment, target liquid, etc.) A water leakage sensor having sensitivity is appropriately selected and used. For example, a highly sensitive leak sensor is used to detect leaks of liquids with relatively high resistance values, such as pure water, and a low sensitivity type is used to detect leaks of liquids with relatively low resistance values, such as tap water. A water leak sensor is used.

  Patent Document 1 discloses, as an example of a high-sensitivity type water leakage sensor, a water leakage formed by twisting together a pair of conductive wires (electrode wires) each covered with an insulating braid that can be passed through a surface active agent. A sensor is disclosed. In this configuration, a pair of conducting wires twisted through the insulating braid acts as an electrode pair over their entire length, and the braid has high water absorption and water retention, so that the sensitivity is high. Patent Document 2 discloses, as an example of a low-sensitivity type water leakage sensor, a wire body in which a pair of conductive wires are entirely covered with an insulating resin coating material, and the coating material is locally broken through and electrically connected to the conductive wires. A water leakage sensor is disclosed in which a plurality of electrode pieces to be attached are attached so as to be alternately connected to individual conductors at predetermined longitudinal positions. In this configuration, since the electrode pieces of the respective polarities are arranged at predetermined positions in the longitudinal direction of the pair of conductive wires, the distance between the electrode pairs is large and the sensitivity is low.

  The high-sensitivity type water leakage sensor described in Patent Document 1 can be directly laid directly on a conductive surface such as a pipe because the electrode wire is covered with an insulating braid over its entire length. On the other hand, since the braid has a high water retention capacity, it is necessary to sufficiently remove the liquid absorbed by the braid in order to restore the initial state after detecting water leakage. Further, due to the high water absorption of the braid, a sensing reaction may occur (that is, malfunction) even for a very small amount of liquid that is not leaked water, such as condensed water. In other words, this water leakage sensor is liable to malfunction due to the detection of a small amount of liquid other than the leakage water, and the recovery work after the water leakage detection processing requires a considerable amount of time. On the other hand, the low-sensitivity type water leak sensor described in Patent Document 2 is made of a non-water-absorbing resin material for the covering material so that the liquid adhering to the electrode and the covering material can be easily removed after sensing the water leak Because it is possible, the recovery work can be performed quickly. On the other hand, since the electrode piece is exposed, it cannot be laid directly on a conductive surface such as a pipe.

  Furthermore, as described in Patent Document 3, there is also proposed a water leakage sensor that is highly sensitive but hardly causes malfunction and that can be easily restored. The water leakage sensor of Patent Document 3 is obtained by locally cutting a covering material at a predetermined longitudinal position with respect to a linear body in which a pair of conducting wires are entirely covered with an insulating resin coating material, and then transverse direction of both the conducting wires. Corresponding portions are locally exposed at a plurality of locations in the longitudinal direction, and this linear body is covered with an insulating mesh member having a relatively low density (that is, coarse mesh). This water leakage sensor is a highly sensitive type because the mesh member exhibits a water retention function in addition to the narrow gap between the electrode pairs, and by using a low density mesh member, the water absorption ability is suppressed and condensation is formed. It prevents malfunctions caused by water, etc., and facilitates liquid removal during recovery.

JP-A-8-271461 Japanese Patent Publication No. 7-39981 JP-A-3-235031

  In the water leakage sensor described in Patent Document 3 described above, the distance between the electrode pairs corresponds to the transverse dimension (for example, about 5 mm) of the striate body. Therefore, when the mesh member is removed, not the leakage water but the laying surface. There is a tendency to detect a small amount of liquid such as condensed water. By covering this highly sensitive striated body with a mesh member having a coarse mesh, a gap with low water absorption is formed between the electrode and the laying surface to prevent malfunction due to condensed water or the like. However, even though the mesh member has a low density, it requires some labor and time to remove the liquid at the time of restoration, compared to a sensor structure made of a bare filament without the mesh member.

  It is an object of the present invention to provide a water leakage sensor that is highly sensitive and that can prevent malfunction due to a small amount of liquid that is not leaked water and that is extremely easy to remove at the time of restoration. It is to provide a sensor.

In order to achieve the above object, an invention according to claim 1 is a water leakage sensor that has a plurality of electrodes spaced apart from each other and senses conduction between arbitrary electrodes as the presence of liquid, and has a wire having electrical insulation. and Jo heartwood, along the surface of the core are positioned individually spirally are spaced apart from each other on the core surface, each of which comprises a plurality of conductors functioning as electrodes, heartwood, the surface A plurality of grooves individually spirally recessed along each of the grooves, and each of the plurality of conductors is partially and fixedly received in each of the grooves, and each of the plurality of conductors is predetermined by the water leakage sensor. continuously over the entire length of the sensing area, it provides a leak sensor characterized by chromatic an exposed surface portion exposed to protrude from the surface of the core.

According to a second aspect of the invention, the water leakage sensor according to claim 1, a plurality of conductors, at a predetermined uniform spacing over the entire length of the sensing area of the leak sensor, on the surface of the core A water leakage sensor is provided.

The invention according to claim 3 provides the water leakage sensor according to claim 1 or 2 , wherein the surface of the core material is a substantially cylindrical surface.

According to a fourth aspect of the present invention, in the water leakage sensor according to any one of the first to third aspects of the present invention, the water leakage sensor according to any one of the first to third aspects further includes a mesh member disposed on the core material and the plurality of conductive wires and having electrical insulation and liquid permeability. A water leakage sensor is provided.

The invention according to claim 5 is the water leakage sensor according to claim 4 , wherein the mesh member includes a plurality of fibrous elements individually wound around the plurality of conductors along the surface of the core material. I will provide a.

  According to the first aspect of the present invention, since the plurality of conducting wires each functioning as an electrode are helically positioned on the core material surface, the minimum interval between the conducting wires on the core material surface is determined by the core material. It is defined as the distance along the substantially circumferential direction. Therefore, by setting the thickness of the core material to be relatively thin such as several millimeters, the minimum distance between the conductors is also several millimeters, and a highly sensitive water leakage sensor capable of sensing a relatively small amount of liquid can be obtained. On the other hand, when a trace amount of liquid such as condensed water that is not leaked water is present on the laying surface of the water leakage sensor, the distance between the conductors for detecting such liquid is the length of the core material regardless of the thickness of the core material. The distance along the direction. In other words, by arranging a plurality of conductors sufficiently apart in the longitudinal direction of the core material, it becomes difficult to detect a small amount of liquid such as condensed water generated on the laying surface, and as a result, a water leakage sensor with few malfunctions. Is obtained. In addition, this water leakage sensor has an extremely simple structure in which a plurality of conductive wires are wound around an electrically insulating core material. Therefore, when water leakage is detected, the liquid adhering to the core material and the conductive wires can be easily recovered. And can be removed quickly.

In addition , by forming each groove on the surface of the core material in a spiral form corresponding to the form required for each conductor as an electrode, a plurality of conductors are wound in a predetermined spiral form along the surface of the core material. Can be easily arranged.

In addition , the presence of a local liquid can be detected at any location within the sensing area of the water leakage sensor. Moreover, since the liquid bridging the conductive wires adheres to the core material surface in a state where it automatically spreads along the conductive wires due to surface tension, it becomes easier for current to flow in the liquid. Even a liquid having a high resistance value can be reliably detected.

According to the second aspect of the present invention, substantially uniform sensitivity can be secured within the sensing area of the water leakage sensor. Moreover, in a water leak sensor, a sensitivity can be easily adjusted by selecting suitably the arrangement | positioning space | interval of several conducting wire.

According to the invention described in claim 3 , it is possible to easily and accurately wind the individual conductors along the surface of the core material.

According to invention of Claim 4 , a water leak sensor can be directly laid as it is on conductive surfaces, such as piping.

According to the fifth aspect of the present invention, a mesh member having a required density can be obtained relatively easily.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
Referring to the drawings, FIG. 1 is a schematic perspective view of a water leakage sensor 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the water leakage sensor 10. The water leak sensor 10 has a pair or a plurality of electrodes spaced apart from each other, and has an electrical configuration that senses conduction between the electrodes as the presence of liquid (that is, water leakage).

  As shown in the figure, the water leakage sensor 10 is positioned by being wound in a spiral manner along the surface 12a of the linear core 12 having electrical insulation and the surface 12a of the core 12 and spaced apart from each other on the surface 12a. A pair of conductive wires 14 and 16. Each of the conductive wires 14 and 16 functions as an electrode of the water leakage sensor 10 and is electrically insulated from each other on the surface 12a of the core material 12 in normal times (when not detected).

  A pair of conducting wires 14 and 16 of the water leakage sensor 10 are connected to a water leakage detector 18 that constitutes a water leakage detection system in cooperation with the water leakage sensor 10, thereby forming a detection circuit. A voltage is always applied to the conducting wires 14 and 16 from the water leakage detector 18. The water leakage sensor 10 is configured such that when a liquid is interposed between the two conductors 14 and 16 and the conductors 14 and 16 are electrically bridged with each other, a current flows through the two conductors 14 and 16 through the liquid. Sense the presence of liquid. The water leakage detector 18 detects and processes, as a liquid sensing signal of the water leakage sensor 10, an electrical resistance value of the detection circuit that fluctuates in response to an increase or decrease in the amount of liquid that bridges both the conductive wires 14 and 16 of the water leakage sensor 10. Perform alerting operations such as alarms.

  In the water leakage sensor 10 having the above-described configuration, a pair of conducting wires 14 and 16 that function as electrodes having different polarities are spirally wound around the surface 12a of the core material 12, and thus both conducting wires on the surface 12a. The minimum interval between 14 and 16 can be defined by the distance along the circumferential direction of the core material 12. Therefore, by making the thickness of the core material 12 relatively thin, such as several millimeters, the minimum distance between the two conductive wires 14, 16 is also several millimeters, and a highly sensitive leak sensor 10 capable of sensing a relatively small amount of liquid. Is obtained.

  On the other hand, when a trace amount of liquid such as condensed water that is not leaked water is present on the laying surface of the water leak sensor 10, the distance between the two conductors 14 and 16 for detecting such liquid is set to the thickness of the core material 12. Regardless, the distance is along the longitudinal direction of the core 12. That is, by arranging the pair of conductive wires 14 and 16 apart from each other in the longitudinal direction of the core material 12 by, for example, about 10 mm, it becomes difficult to detect a small amount of liquid such as condensed water generated on the laying surface. The water leakage sensor 10 with less operation is obtained.

  Moreover, since the water leakage sensor 10 has a very simple structure in which the pair of conductive wires 14 and 16 are wound around the electrically insulating core material 12, the core material 12 and the conductive wires 14 are detected when the water leakage sensor 10 is restored to the initial state after detecting the water leakage. , 16 can be removed easily and quickly. As described above, the water leakage sensor 10 is highly sensitive and can prevent malfunction due to a small amount of liquid that is not leakage water, and the removal of the liquid at the time of restoration is extremely easy.

  In the water leakage sensor 10 described above, it is advantageous from the viewpoint of facilitating restoration work that the core material 12 is formed of an insulating resin material having a low water absorption rate, such as polyvinyl chloride. Moreover, it is preferable that each conducting wire 14 and 16 is formed from a good conductor which does not corrode easily, such as stainless steel, and it is desirable to have a form of a stranded wire from the viewpoint of ensuring mechanical strength and easy handling. Furthermore, it is desirable that the core material 12 and each of the conductive wires 14 and 16 have flexibility so that the water leakage sensor 10 can be bent and laid along various laying surfaces.

  As shown in FIG. 2, the core 12 includes a pair of grooves 20 and 22 that are individually spirally recessed along the surface 12 a, and each of the pair of conductors 14 and 16 includes the grooves 20 and 22. Each of 22 can be configured to be fixedly received. According to this configuration, by forming the grooves 20 and 22 in the surface 12a of the core 12 in advance in a spiral form corresponding to the form required as an electrode for each of the conductors 14 and 16, both the conductors 14 and 14 16 can be easily arranged in a predetermined spiral winding form along the surface 12 a of the core 12. In addition, such a water leak sensor 10 is produced by inserting the material of the core material 12 and the pair of conductors 14 and 16 through the extrusion die at the same time and applying an appropriate twisting operation using, for example, an extruder. You can also.

  In addition, as shown in FIG. 1, the pair of conductors 14 and 16 are continuously provided on the surface of the core material 12 over at least a substantially entire length of a predetermined sensing region (that is, a predetermined length range) of the water leakage sensor 10. Advantageously, exposed surface portions 14a, 16a are exposed from 12a. According to this configuration, the presence of a local liquid can be detected at any location within the detection area of the water leakage sensor 10. Moreover, since the liquid bridging the pair of conductors 14 and 16 adheres to the core material surface 12a in a state of automatically spreading along the conductors 14 and 16 due to the surface tension, it becomes easier for current to flow in the liquid. For example, even a liquid having a relatively high resistance value such as pure water can be reliably detected. In this case, in the cross section shown in FIG. 2, it is preferable that about 50% of the surface of each of the conducting wires 14 and 16 is the exposed surface portions 14a and 16a (of course, various exposure rates other than 50% may be adopted. it can).

  As shown in FIG. 1, the pair of conductors 14 and 16 are disposed on the surface 12 a of the core material 12 at a uniform mutual interval over at least the substantially entire length of the predetermined sensing area of the water leakage sensor 10. It is advantageous. According to this configuration, substantially uniform sensitivity can be ensured within the sensing region of the water leakage sensor 10. In particular, the winding pitch P (FIG. 1) of one conductor 14 (16) is 10 mm ≦ P ≦ 100 mm, preferably 20 mm ≦ P ≦ 50 mm, and the pair of conductors 14 and 16 are opposite to each other on the core surface 12a. By arranging them at a phase difference of 180 degrees (that is, a phase difference of 180 degrees), such an equally spaced arrangement can be obtained. Here, if the winding pitch P of each conducting wire 14 and 16 is less than 10 mm, the sensitivity becomes too high and a malfunction due to condensed water tends to occur. Moreover, when the winding pitch P of each conducting wire 14 and 16 exceeds 100 mm, the sensitivity becomes too low and it becomes difficult to answer the demand for high sensitivity. In the water leakage sensor 10, the sensitivity can be easily adjusted by appropriately selecting the winding pitch P of the conductive wires 14 and 16 within the above range.

  Moreover, as shown in FIG. 2, it is preferable that the surface 12a of the core material 12 is a substantially cylindrical surface. According to this structure, each conducting wire 14 and 16 can be wound spirally easily and correctly along the core material surface 12a. However, the present invention is not limited to this, and the core material 12 having the surface 12a of various shapes such as an ellipse and a polygon can be employed in the cross section of FIG. In addition, when extruding the core material 12, as described above, the conductor wires 14 and 16 are wound around the core material surface 12 a before the core material 12 is solidified. , 16 can be fixed to the core 12. Alternatively, the conductive wires 14 and 16 may be fixed to the grooves 20 and 22 of the core material 12 with, for example, an adhesive.

  3 and 4 show a water leakage sensor 30 according to another embodiment of the present invention. The water leakage sensor 30 has a configuration in which an appropriate mesh member 32 is added to the water leakage sensor 10 described above. Since the other structure of the water leak sensor 30 is substantially the same as the water leak sensor 10, a corresponding reference symbol is assigned to a corresponding component, and description thereof is omitted.

  That is, the water leakage sensor 30 is further provided with a mesh member 32 that is disposed over the core material 12 and the pair of conductive wires 14 and 16 and has electrical insulation and liquid permeability. The mesh member 32 is disposed so as to cover the entire length of the pair of conductive wires 14 and 16 from the outside at least in a predetermined sensing region of the water leakage sensor 30. With such a configuration, the water leakage sensor 30 can be directly laid directly on a conductive surface such as a pipe.

  The net-like member 32 of the water leakage sensor 30 has a structure that is low in density (that is, coarse) so that the water retention function cannot be exhibited by itself. This is because the water leakage sensor 30 is sufficiently sensitive as described above with respect to the water leakage sensor 10 even without the mesh member 32 and does not need to contribute to the sensitivity of the mesh member 32. As a result, although the water leakage sensor 30 has the mesh member 32, it is possible to prevent a malfunction as in the case of the water leakage sensor 10, and it is very easy to remove the liquid at the time of restoration.

  The net member 32 is advantageously formed of an insulating resin material having a low water absorption and excellent mechanical strength, such as polypropylene, polyethylene terephthalate, and polyester. Thereby, the mesh member 32 can exhibit an auxiliary fixing function of the pair of conductive wires 14 and 16 with respect to the surface 12 a of the core material 12 and a mechanical protection function of both the conductive wires 14 and 16.

  The mesh member 32 can include a plurality of fibrous elements 34 that are individually wound around the surface 12a of the core 12 so as to surround the pair of conductors 14 and 16. In the illustrated embodiment, eight fibrous elements 34 are individually wound along the surface 12 a of the core material 12 to constitute the mesh member 32. More specifically, the four left-handed fibrous elements 34a and the four right-handed fibrous elements 34b (FIG. 4) have a total length within at least a predetermined sensing area of the water leakage sensor 30. The mesh members 32 are arranged on the core material surface 12a at uniform intervals over the whole, thereby forming a net-like member 32 having a uniform density as a whole. In particular, the effect described above is achieved by setting the winding pitch of one fibrous element 34a (34b) to 10 mm to 100 mm, preferably 20 mm to 50 mm, equivalent to the winding pitch P of the conductive wires 14 and 16 described above. Thus, the net member 32 having a necessary and sufficient density can be obtained relatively easily. In addition, the diameter of the fibrous element 34 can be 0.1 mm-0.6 mm.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the illustrated embodiments, and various modifications can be made within the disclosure of each claim recited in the claims. For example, not only a configuration having a pair of conductive wires as electrodes of a water leakage sensor, but also a configuration having a plurality of three or more conductive wires can be adopted. In this case, for example, one conductive wire can be used for specifying the water leakage position within the sensing area of the water leakage sensor.

  In the water leakage sensor 30 described above, the liquid sensing ability with respect to tap water (conductivity 140 μS / cm) and pure water (conductivity 0.7 μS / cm) was measured. In the experiment, a leak sensor 30 was laid on an acrylic plate, and a DC 9 V pulse voltage was applied between the pair of conductors 14 and 16, and tap water and pure water were directly dropped onto the leak sensor 30 with a dropper. The change in the resistance value of the detection circuit was measured. As a comparative example, a similar experiment was performed on a conventional low-sensitivity type water leakage sensor (manufactured by 3M, B-3P) and a conventional high-sensitivity water leakage sensor (manufactured by 3M, S-1F).

  As a result of the experiment, the leak sensor 30 does not generate a sensing signal when the amount of dripping liquid is less than 1 milliliter with respect to tap water, and malfunctions equivalent to the conventional low sensitivity type leak sensor (B-3P). Stable sensitivity with less The conventional high-sensitivity type water leakage sensor (S-1F) senses such a small amount of tap water, and there is a concern about malfunction due to condensed water. In addition, with respect to pure water, the water leakage sensor 30 generates a sensing signal when the amount of dripping liquid exceeds 4 ml, and exhibits excellent sensitivity equivalent to that of a conventional high sensitivity type water leakage sensor (S-1F). It was. The conventional low-sensitivity water leakage sensor (B-3P) has been difficult to detect pure water regardless of the amount of liquid. Moreover, the water leakage sensor 30 can easily wipe off the adhering liquid, and the recoverability is proven.

It is a schematic perspective view of the water leak sensor by one Embodiment of this invention. It is sectional drawing along line II-II of the water leak sensor of FIG. It is a schematic perspective view of the water leak sensor by other embodiment of this invention. It is sectional drawing along line IV-IV of the water leak sensor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 Water leak sensor 12 Core material 14, 16 Conductor 18 Water leak detection part 20, 22 Groove 32 Mesh member 34 Fibrous element

Claims (5)

In a water leakage sensor having a plurality of electrodes spaced apart from each other and sensing conduction between any electrodes as the presence of liquid,
A linear core material having electrical insulation;
A plurality of conductors individually helically positioned along the surface of the core material and spaced apart from each other on the surface, each serving as the electrode;
Equipped with,
The core includes a plurality of grooves that are individually spirally recessed along the surface, and each of the plurality of conductors is partially and fixedly received in each of the grooves,
Each of said plurality of lead wires, continuously over the entire length of a predetermined sensing area of the leak sensor, to have a exposed surface portion exposed protruding from said surface of said core,
Water leakage sensor characterized by. Wherein the plurality of conductors, in advance all uniform spacing over the length of the sensing area which defines the leak sensor, disposed on the surface of the core, leak sensor according to claim 1. The water leakage sensor according to claim 1 or 2 , wherein the surface of the core material is a substantially cylindrical surface. The water leakage sensor according to any one of claims 1 to 3 , further comprising a mesh member disposed over the core material and the plurality of conductive wires and having electrical insulation and liquid permeability. The water leak sensor according to claim 4 , wherein the mesh member includes a plurality of fibrous elements individually wound around the plurality of conductive wires along the surface of the core material.

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