Leak detection device and instantaneous water heater with such a

Description

[0001] The present invention relates to a device for heating a fluid, according to the preamble of claim 1.

[0002] Such a device is known, for example, from US 2010 / 086289 A1.

[0003] Such instantaneous water heaters and methods are used for the preparation of hot water, in particular for heating domestic hot water. Specifically, the control unit regulates the electric heating element so that the domestic hot water is heated to a predetermined set temperature. Such devices for heating a fluid regularly have a number of points where leakage can potentially occur. Such leakage can occur, for example, due to the failure of sealing elements such as O-rings, seals, or screw connections, but also due to leaks in the heating element itself. In principle, any ingress of water, whether through leaks in the device according to the invention itself or through the ingress of splashing or jet water from the outside, must be considered problematic.Leakage within the meaning of the present invention therefore means any occurrence of fluids in the interior of the housing, whether due to leaks occurring in the fluid-carrying parts in the device itself, or due to fluids penetrating from the outside.

[0004] Leakage detection systems are well-known in household appliances such as dishwashers and washing machines. Typically, a drip tray is located at the bottom of the housing to collect dripping or leaking water. A float switch with a buoyancy element is positioned in this tray. When water is present, the float rises to the surface of the water, thus activating a microswitch. A disadvantage of these known leakage detection systems is that they only trigger when a significant amount of water has accumulated in the drip tray, and they only function reliably when the appliance is installed in its intended upright position. Another drawback is that smaller leaks, which do not immediately lead to a substantial accumulation of water in the drip tray, will not be detected initially.

[0005] It is therefore an object of the present invention to propose a device that ensures reliable detection of leaks and / or the occurrence of fluid or water accumulation, regardless of the installation position. Furthermore, the object is to propose an electronic instantaneous water heater with such detection capability.

[0006] The problem is solved by a device with the aforementioned features in that the leak detection device comprises at least two measuring electrodes arranged at least substantially circumferentially on the housing base and / or the housing cover, and the leak detection device is designed to detect wetting of the measuring electrodes with fluid by measuring the resistance between the measuring electrodes and, in the event of detected wetting, to provide a leak detection signal. The device according to the invention offers the advantage that the occurrence of a leak or small accumulations of liquid are always reliably detected, regardless of the installation position. Reliable detection is always ensured by the measuring electrodes being arranged at least substantially circumferentially, i.e., either completely or at least partially.It is neither necessary for a large quantity of water or liquid to accumulate in one place, nor is the installation position relevant. The housing base is also referred to simply as the base body.

[0007] A preferred embodiment of the invention is characterized in that the measuring electrodes are designed as metal conductor elements. These metal conductor elements have the advantage of good electrical conductivity, such that their electrical resistance is negligibly small compared to the resistance between the two measuring electrodes when wetted with water. In this way, even the smallest amounts of water can be detected with the measuring electrodes according to the invention. Alternatively, the measuring electrodes are formed from electrically conductive plastic.

[0008] Another advantageous embodiment of the invention is characterized in that the measuring electrodes are materially bonded to the housing base and / or the housing cover. For example, the measuring electrodes can be arranged directly in the injection molding process during the manufacturing of the housing base and / or the housing cover. In this way, the metal conductor elements can be directly connected to the housing base or the housing cover during production. If the measuring electrodes are formed from the aforementioned electrically conductive plastic, this plastic can be directly injection molded onto the housing base.

[0009] A further advantageous embodiment of the invention is characterized in that the housing base and / or the housing cover have receiving elements for the force-fit and / or form-fit arrangement of the measuring electrodes on them. The receiving elements can, for example, be designed as an annular groove or annular recess that is at least partially circumferential, the clear width of which is slightly less than the width of the measuring electrodes, so that the latter are held by the receiving elements in a force-fit and / or form-fit manner, preferably with a tight fit. The aforementioned receiving elements generally offer the advantage that the measuring electrodes are arranged on or in the receiving elements after the housing base and / or the housing cover have been manufactured.

[0010] A preferred embodiment of the invention is characterized by the fact that the measuring electrodes are made of a corrosion-resistant material. This offers the advantage of ensuring consistently good conductivity of the measuring electrode surface, thus preventing the formation of a poorly conductive surface layer. In this way, appropriate sensitivity for leak detection is guaranteed at all times.

[0011] A preferred embodiment of the invention is characterized by the fact that first contact elements are arranged on the housing base and second contact elements are arranged on the housing cover. When the housing cover is mounted on the housing base, these contact elements make electrical contact with each other and are each electrically connected to the measuring electrodes. Advantageously, the measuring electrodes are thus arranged not only on the housing base but also on the housing cover, and are electrically connected to each other via the aforementioned contact elements—at least when the housing cover is mounted on the housing base. This offers the advantage that leakage or free water is detected not only in the area of ​​the housing base but also in the area of ​​the housing cover. This is particularly helpful for detecting water that penetrates from the outside as jet or splash water, in order to detect it as early as possible.

[0012] According to a further preferred embodiment of the invention, the measuring electrodes are aligned parallel to each other. This parallel connection ensures that any leakage water is reliably detected both in the area of ​​the housing base and in the area of ​​the housing cover.

[0013] A further advantageous embodiment of the invention is characterized in that the distance between the measuring electrodes is constant along their length. This ensures that any water present in the area of ​​the measuring electrodes exhibits the same electrical resistance at every point on the housing base and / or the housing cover from the perspective of the measuring electrodes, so that leakage can be detected equally on all sides.

[0014] According to a further preferred embodiment, the measuring electrodes each form a closed loop. Advantageously, this provides all-round monitoring for the occurrence of leaks. In addition, the device according to the invention is designed to reliably detect any jet or splash water penetrating from the outside from all directions.

[0015] Another advantageous embodiment of the invention is characterized in that the measuring electrodes are arranged such that they completely enclose all fluid-carrying parts at least once. This offers the advantage that all parts where there is a general risk of leakage are monitored by means of the device according to the invention. Alternatively, it is also possible to surround individual fluid-carrying subassemblies with measuring electrodes. These measuring electrodes then each form double partial-enclosure electrodes. Each group of measuring electrodes consisting of the aforementioned double partial-enclosure electrodes is preferably connected electrically in parallel with the other double partial-enclosure electrodes, so that even the wetting of at least one of these measuring electrode groups leads to the detection of a leak and the provision of the leakage signal.

[0016] Another advantageous embodiment of the invention is characterized in that the control unit is configured to de-energize the electric heating unit upon receiving a leakage signal. This ensures that the power is immediately cut off upon detection of a leakage, thereby preventing any potential consequential damage from impermissible leakage currents, short circuits, or the risk of electric shock to the user.

[0017] A further advantageous embodiment of the invention is characterized in that the control unit is designed to output an acoustic and / or visual warning message via an output unit when a leakage signal is provided. This offers the advantage that a user is immediately alerted to a detected leak or the presence of water inside the device.

[0018] Furthermore, the problem is solved by an electronic instantaneous water heater with the aforementioned features in that the housing base forms the rear wall of the water heater and the electric heating element is designed as a bare wire heating device. The device according to the invention is preferably used in such electronic instantaneous water heaters. A particular advantage is that the instantaneous water heater can be installed in various mounting positions, as reliable leak detection is always ensured regardless of its installation position. In addition, the instantaneous water heaters according to the invention are also able to detect any jet and / or splash water that may enter as a leak.

[0019] Further preferred and / or advantageous features and embodiments of the invention will become apparent from the dependent claims and the description. Particularly preferred embodiments are explained in more detail with reference to the accompanying drawing. The drawing shows: Fig. 1 a schematic view of an electronic instantaneous water heater with parts of the device according to the invention and Fig. 2 a schematic view of a housing cover.

[0020] Figure 1 The device according to the invention is shown schematically as an electronic instantaneous water heater. The present device serves to heat a fluid and comprises a housing base 10, a fluid inlet 11, and a fluid outlet 12. An electric heating unit 13, designed to heat the fluid, is arranged between the fluid inlet 11 and the fluid outlet 12. Figure 1 The device is shown in an exploded view. It further comprises a control unit 14, which is located in Figure 1This is shown as an example in a printed circuit diagram. The control unit 14 is configured to control the electric heating unit 13 to heat the fluid to a predetermined setpoint temperature.

[0021] The device also includes a - in the Figure 2 Schematically depicted housing cover 15, which is designed to be detachably arranged on the housing base body 10. The housing cover 15 is in Figure 2 only schematically indicated with a view towards the inside of the hood.

[0022] According to the invention, the control unit 14 has a leak detection device. This leak detection device comprises at least two measuring electrodes 16, 17. These are either - as in Figure 1 shown by way of example - on the housing base body 10 and / or - as in Figure 2schematically shown – in the housing cover 15 – arranged at least substantially circumferentially. At least substantially circumferentially, in the context of the present invention, means that the measuring electrodes 16, 17 are arranged at least partially circumferentially, or even completely circumferentially.

[0023] The leak detection device with measuring electrodes 16, 17 is designed to detect contact with a fluid exhibiting at least slight electrical conductivity by measuring the ohmic resistance between the measuring electrodes 16, 17. Furthermore, it is configured to provide a leak detection signal in the event of detected contact.

[0024] Preferably, the measuring electrodes 16, 17 are designed as metal conductor elements. Such metal conductor elements exhibit good electrical conductivity, i.e., their electrical resistance is negligibly small compared to the resistance between the two measuring electrodes 16, 17 when wetted with an electrically conductive fluid. Alternatively, the measuring electrodes are formed from electrically conductive plastic.

[0025] Preferably, the measuring electrodes 16, 17 are metallurgically bonded to the housing base 10 and / or the housing cover 15. The measuring electrodes 16, 17 are, for example, injection-molded onto the housing base 10 and / or the housing cover 15, or are positioned directly on it during the injection molding process. If the measuring electrodes are formed from the aforementioned electrically conductive plastic, this plastic can be directly injection-molded onto them.

[0026] Preferably, the housing body 10 and / or the housing cover 15 comprise receiving elements (not shown in the drawing) for the force-fit and / or form-fit arrangement of the measuring electrodes 16, 17 on them. The receiving elements are designed, for example, as an annular groove or annular recess that is at least partially circumferential. In particular, their clear width is slightly less than the width of the measuring electrodes 16, 17. In this way, the electrodes are seated in the receiving elements with a close fit, either force-fit and / or form-fit, and are held by them. Preferably, the measuring electrodes 16, 17 are made of a corrosion-resistant material.

[0027] Preferably, first contact elements 18 are arranged on the base body 10 and second contact elements 19 are arranged on the housing cover 15. The first and second contact elements 18, 19 are shown schematically in the drawing and do not correspond to the actual physical design. The contact elements 18, 19 are designed to electrically connect the measuring electrodes 16, 17 arranged on the housing cover 15 to the measuring electrodes 16, 17 of the housing base body 10. The contact elements 18, 19 can, for example, be designed as spring contacts that automatically connect the measuring electrodes 16, 17 electrically when the housing cover 15 is placed on the base body 10. If the housing cover 15 is removed from the base body 10, for example for maintenance purposes, the electrical connection is automatically released. It is also possible for the contact elements 17, 19 to be electrically connected to each other via flexible cable connections and / or plug connections.

[0028] As in the Figure 1 As indicated, the measuring electrodes 16, 17 are preferably aligned parallel to each other. It is also more preferably that the measuring electrodes 16, 17 arranged in the housing cover 15 are aligned parallel to each other. Figure 2 The measuring electrodes 16, 17 are not explicitly shown as two measuring electrodes 16, 17, but are only indicated in a simplified manner by a circumferential line.

[0029] Preferably, the distance between the measuring electrodes 16, 17 is constant along their length. This ensures that any water present in the area of ​​the measuring electrodes 16, 17 has the same electrical resistance at every point on the housing base 10 and / or the housing cover 15 from the perspective of the measuring electrodes 16, 17, so that leak detection can be carried out equally on all sides.

[0030] Preferably, the measuring electrodes 16, 17 are each designed as a closed loop. This provides all-round monitoring for the occurrence of leaks or for the possible ingress of splashing or jet water.

[0031] In particular, the measuring electrodes 16, 17 are arranged such that they completely or substantially enclose all fluid-carrying parts at least once. Alternatively, it is also possible to surround only individual fluid-carrying subassemblies with measuring electrodes 16, 17. These measuring electrodes 16, 17 then each form double partial-enclosure electrodes (not shown in the drawing).

[0032] The control unit 14 is further preferably designed to switch off the electric heating unit 13 when a leakage signal is provided, in order to immediately exclude, for example, possible consequential damages caused by impermissible leakage currents, short circuits or a risk to the user from electric shock in every case.

[0033] The control unit 14 is preferably further designed to output an acoustic and / or optical warning message by means of an output unit - not shown in the drawing - when a leakage signal is provided.

[0034] In the electronic instantaneous water heater shown in the drawing, the housing base body 10 forms the back wall of the instantaneous water heater and the electric heating unit 15 is preferably designed as a bare wire heating device.

Claims

1. Apparatus for heating a fluid, comprising a housing base body (10), a fluid inlet (11) and a fluid outlet (12), at least one electric heating unit (13) arranged between the fluid inlet (11) and the fluid outlet (12) and adapted to heat the fluid, a control unit (14), which is adapted to correspondingly control the electric heating unit (13) for heating the fluid to a predefined target temperature, a housing cover (15), which is configured to be detachably arranged on the housing base body (10), characterised in that the control unit (14) has a leakage detection device, wherein the leakage detection device comprises at least two measuring electrodes (16, 17), which are at least substantially circumferentially arranged on the housing base body (10) and / or the housing cover (15), and the leakage detection device is configured to detect wetting of the measuring electrodes (16, 17) with fluid by measuring the resistance between the measuring electrodes (16, 17) and, if wetting is detected, to provide a leakage detection signal.

2. Apparatus according to claim 1, characterised in that the measuring electrodes (16, 17) are configured in the form of metal conductor elements.

3. Apparatus according to claim 1, characterised in that the measuring electrodes (16, 17) are formed by electrically conductive plastic.

4. Apparatus according to any one of claims 1 to 3, characterised in that the measuring electrodes (16, 17) are connected to the housing base body (10) and / or the housing cover (15) by substance-to-substance bonding.

5. Apparatus according to any one of claims 1 to 4, characterised in that the housing base body (10) and / or the housing cover (15) have receiving elements for the force-based and / or interlocking arrangement of the measuring electrodes (16, 17) thereon.

6. Apparatus according to any one of claims 1 to 5, characterised in that the measuring electrodes (16, 17) consist of a corrosion-resistant material.

7. Apparatus according to any one of claims 1 to 6, characterised in that first contact elements (18) are arranged on the housing base body (10) and second contact elements (19) are arranged on the housing cover (15), which contact elements, when the housing cover (15) is arranged on the housing base body (10), electrically contact one another and are each electrically connected to the measuring electrodes (16, 17).

8. Apparatus according to any one of claims 1 to 7, characterised in that the measuring electrodes (16, 17) are oriented parallel to one another.

9. Apparatus according to any one of claims 1 to 8, characterised in that the distance of the measuring electrodes (16, 17) from one another is constant over their length.

10. Apparatus according to any one of claims 1 to 9, characterised in that the measuring electrodes (16, 17) each form a closed loop.

11. Apparatus according to any one of claims 1 to 10, characterised in that the measuring electrodes (16, 17) are arranged in such a manner that they completely surround all the fluid-conducting parts at least once.

12. Apparatus according to any one of claims 1 to 11, characterised in that the control unit (14) is configured to de-energise the electric heating unit (13) when a leakage signal is provided.

13. Apparatus according to any one of claims 1 to 11, characterised in that the control unit (14) is configured to output an acoustic and / or visual warning message by means of an output unit when a leakage signal is provided.

14. Electronic continuous flow heater comprising an apparatus according to any one of claims 1 to 13, wherein the housing base body (10) forms the rear wall of the continuous flow heater and the electric heating unit (13) is configured in the form of a bare-wire heating device.