Aquarium heater

Abstract

Aquarium heater, namely an electric heater to be introduced into an aquarium as a separate component, with a heater housing (2, 3) accommodating at least one heating element (1) and with a mains connection cable (4) for connecting the heater to a mains socket carrying mains voltage, wherein the heater housing (2, 3) consists of a glass body (2) and a water-sealed connection space (3), in which connections are arranged which are galvanically connected to one wire of the mains connection cable (4), characterized in that at least one electrically conductive element (5, 5'), namely an element (5, 5') consisting of an electrically conductive material, is arranged on the glass body (2) or along the glass body (2) of the heater housing (2, 3), which element is connected to a wire of the three-wire cable connecting this at least one electrically conductive element (5, 5') to a protective conductor contact of the mains socket,is galvanically coupled to a mains connection cable (4) provided with a plug (7) having a protective contact (8).

Description

[0001] The invention relates to an aquarium heater. It particularly relates to an electric heater, preferably in rod form, that can be incorporated into an aquarium as a separate component. Generic electric heaters essentially consist of at least one heating element accommodated in a heater housing and are equipped with a power cable. Furthermore, the heaters are very often also equipped with a temperature control device. The terms "aquarium heater" or "aquarium heater" are also used synonymously for such heaters, without this expressing or constituting a technical difference from the subject matter of the invention considered here and the embodiments described for it in the context of the following illustrations and the claims.

[0002] In the vast majority of cases, a large portion of the housing of aquarium heaters of the aforementioned type, i.e., heaters designed as separate components, is made of glass, particularly the part of the heater housing surrounding the actual heating element. The heaters are equipped with a two-wire power cable for connecting the heater to a mains socket that supplies power to both the heating element and the temperature control device (preferably present).

[0003] There are probably several reasons why the majority of the housing, at least in heaters commonly used in Europe, is typically made of glass. One possible reason is that a glass housing section surrounding the actual heating element is more cost-effective than a metal one. The latter would require either very high-quality and therefore expensive steels or precious metals such as titanium to ensure corrosion resistance, as the housing is constantly immersed in water during use.

[0004] By using glass for the heater housing, the radiant heat emanating from the heating element surrounded by the glass can be used to heat the water in the aquarium in addition to the heat introduced by conduction.

[0005] However, in the context of the application discussed here, glass also has a disadvantage: its use in the housing of electric aquarium heaters. This disadvantage is its significantly lower mechanical stability compared to metal or steel. In practice, especially among end users, i.e., home users or aquarists, the glass housing parts of heaters therefore frequently break. Causes of this include mechanical damage caused by impacts, such as those that can occur when handling the aquarium, for example, when cleaning it.

[0006] Collapsing rock decorations can also damage, particularly shatter, glass parts of electric aquarium heaters. Occasionally, when draining water from the aquarium, for example, for cleaning purposes, the heater is not disconnected from the power supply. As a result of the falling water level, exposed parts (i.e., those located outside the water) overheat and, if made of glass, shatter.

[0007] However, damage to or destruction of an aquarium heater or heater housing that is largely made of glass can not only result in economic or financial loss for the owner or operator of an aquarium. It can also lead to accidents. In this respect, there is not only the risk of someone being injured by the glass splinters of a bursting heater housing, but also the much greater risk that a person caring for the aquarium and reaching into the water could suffer an electric shock due to the heat- and electricity-conducting heating element being exposed if the heater housing is destroyed. The inventors have learned of numerous such cases and have even been affected by some of them themselves.

[0008] The object of the invention is to solve the above-mentioned problem, namely to provide an aquarium heater or an electric heater with a glass housing for aquariums, in which the risk of electric shock in the event of mechanical damage to the glass housing part of the heater is significantly reduced or such a risk is almost completely eliminated.

[0009] The object is achieved by an aquarium heater having the features of claim 1. Advantageous embodiments and further developments of the invention are provided by the subclaims.

[0010] The aquarium heater that solves the problem is an electric heater that is installed as a separate component in an aquarium. Therefore, the invention does not – and this should be expressly emphasized again at this point – relate to permanently installed aquarium heaters, which do not usually have the problems described above. Rather, the heater considered here is, in a sense, a purchased part, namely a component that is additionally inserted into an aquarium when needed or when required. As such, although widely used, it is not a mandatory part of every aquarium. In its capacity as a separate component that is additionally installed in an aquarium, such an electric heater could also be referred to as a mobile aquarium heater.The term aquarium heater and its abbreviated form heater are used synonymously in the description and claims, but in this context, as already explained, always refer to a separate component used to heat an aquarium.

[0011] The heater has a housing accommodating at least one heating element, which, for the reasons stated above and in accordance with the stated task, is largely made of glass. The heater also has a power cable for connecting the heater to a mains socket carrying mains voltage (230 V AC) and is preferably (but not necessarily) equipped with a temperature control. The heater housing mentioned above consists, more precisely, of a glass body surrounding the heating element and a water-tight connection chamber in which terminals are arranged that are galvanically connected to one wire of the power cable each. In the area of the latter connection chamber, the heater housing is typically not made of glass, but can be made of a plastic, for example.

[0012] To achieve this objective, at least one electrically conductive element, i.e., an element made of an electrically conductive material, is arranged on the glass body of the heater housing or along this glass body, i.e., extending along the glass body. The at least one electrically conductive element on the heater housing is galvanically coupled to a wire of the power cable, which in the proposed solution is three-wire and equipped with a plug with a protective contact, connecting this element to a protective conductor contact of the power socket. This ensures that, in the event of damage to the glass body or its destruction due to water penetrating into the interior of the housing, a fault current or a short circuit occurs between the heating element, which is supplied with the mains voltage, and the metallic element of the housing connected to the protective conductor contact.A short circuit will trigger the fuse protecting the socket used for the heater against the occurrence of high currents, such as a corresponding residual current device (RCD).

[0013] In principle, various materials can be considered for the design of the previously mentioned electrically conductive element arranged on the glass body of the heater housing or extending along it. For example, it could be made of carbon or a conductive polymer. However, for a practical implementation of the proposed solution, metal will preferably be used, i.e. the electrically conductive element will be designed as a metal element. Regardless of the material, it would be conceivable to arrange the at least one electrically conductive element on the inside of the glass body. Such a configuration is, as should be expressly pointed out at this point, encompassed by the first claim 1, which characterizes the aquarium heater proposed to solve the problem in its basic design.

[0014] However, not least for manufacturing reasons, the electrically conductive element, which is galvanically connected to the protective conductor contact, will be arranged on the outside of the glass body. According to an embodiment considered advantageous in this respect, the at least one electrically conductive element can be realized, for example, by a metal surface vapor-deposited onto an outer surface of the glass body. However, to form an electrically conductive element, a corresponding flat metal element can also be glued to the glass body (on its inside or preferably on its outside).

[0015] It is also conceivable for at least one strip- or rod-shaped electrically conductive element, preferably a metal element, to protrude from the connection space. In this embodiment, the heater housing, for example, has a larger cross-sectional area than the glass body (a larger diameter in the case of a rod-shaped heater) in the connection space area, from whose edge region, which protrudes beyond the cross-sectional area of the glass body, one or more strip- or rod-shaped electrically conductive elements protrude, extending along the glass body.The electrically conductive element or the metal element is, for example, fixed in the connection compartment and can be cast into the housing wall of the housing part of the connection compartment made of a corresponding material, projecting through its housing, with a short section length corresponding to the wall thickness of the connection compartment.

[0016] Preferably, the heater is designed in the form of a heating rod, as is already known and generally customary. In this respect, the glass body of the heater housing can be a cylindrical glass bulb. This cylindrical glass bulb, which surrounds the at least one heating element, is connected to the sealed connection chamber, which forms another part of the heater housing and is made, for example, of a plastic.

[0017] The specific design of the electrically conductive element or metal element can be such that a metal strip forming the electrically conductive element is vapor-deposited on the outside of the glass body of the heater housing. This metal strip extends in a U-shape from a first longitudinal side of the heating rod in the longitudinal direction thereof and beyond its end facing away from the connection space to a second longitudinal side opposite the first longitudinal side. However, a design is also conceivable in which a metal strip forming the electrically conductive element is vapor-deposited on the outside of the glass body and extends spirally around the glass body of the heating rod in the longitudinal direction of the heating rod. A further alternative possibility is for the at least one electrically conductive element to be formed by a metal mesh surrounding the glass body of the heater housing in the manner of a cage.Such a metal mesh also offers a certain degree of mechanical protection for the vitreous body.

[0018] The temperature control device already mentioned several times can, if present, be located together with the connections for the wires of the power cable within the part of the heater housing that forms the connection compartment. In the area of the connection compartment, the heater housing can, as already mentioned, be made of a plastic, a rubber-like polymer, or even a cast resin.

[0019] Starting from the Fig. Figure 1 provides an exemplary embodiment of the invention and explains it below. The figure shows this exemplary embodiment in a schematic, sketchy representation.

[0020] Essential components of the aquarium heater or heater, here a heating rod, are the housing 2, 3 accommodating a heating element 1 and a power cable 4 for connecting the electric heater to a mains socket (not shown) to which the mains voltage of the public power grid is applied and which is protected by a residual current device. In addition, a component of the heater - this is assumed here - is a temperature control device (not shown), which is of course also supplied with power via the power cable 4 and is in operative connection with the heating element 1.

[0021] The heating housing 2, 3 consists of a glass body 2 surrounding the heating element 1 and a connection compartment 3 in which the mains connection cable 4 is connected to corresponding terminals provided for this purpose in the connection compartment 3 (in the Fig.1 not shown). In this case, the heating element is equipped, unlike in practice, with a three-wire mains connection cable 4 and a protective contact plug (plug 7 with protective contact 8) attached to its free end. The heating element is supplied with mains voltage via a wire carrying the mains voltage and the neutral conductor.

[0022] The third wire of the power cable 4, namely the protective conductor, is galvanically connected (not shown in detail here) to two strip-shaped metallic elements 5, 5', which are vapor-deposited onto the glass bulb (glass body 2) of the heater housing 2, 3 and extend in its longitudinal direction 9. The power cable 4 also supplies power to the temperature control device located inside the connection compartment 3 (also not shown here, as mentioned).

[0023] Should the glass body 2 of the heater housing 2, 3 be accidentally damaged or destroyed during operation of the heater, i.e., when the plug 7 of the power cable 4 is plugged into the (not shown) mains socket, this will result in a fault current or a short circuit between the heating element 1 and the metal strips galvanically connected to the protective conductor (conductive element 5, 5') and, in any case in the case of a short circuit, in the subsequent tripping of an earth leakage circuit breaker protecting the aforementioned mains socket. The rapid tripping of such an earth leakage circuit breaker immediately de-energizes the heater, thus protecting any person who may have a hand in the aquarium, which is fully or partially filled with water, from electric shock.

Claims

[1] Aquarium heater, namely an electric heater to be introduced into an aquarium as a separate component, with a heater housing (2, 3) accommodating at least one heating element (1) and with a mains connection cable (4) for connecting the heater to a mains socket carrying mains voltage, wherein the heater housing (2, 3) consists of a glass body (2) and of a connection space (3) sealed against water, in which connections are arranged which are galvanically connected to one wire of the mains connection cable (4), characterized bythat at least one electrically conductive element (5, 5'), namely an element (5, 5') made of an electrically conductive material, is arranged on the glass body (2) or along the glass body (2) of the heater housing (2, 3), which element is galvanically coupled to a wire of the three-wire mains connection cable (4) provided with a plug (7) having a protective contact (8), said wire connecting said at least one electrically conductive element (5, 5') to a protective conductor contact of the mains socket. [2] Aquarium heater according to claim 1, characterized by that the heater is equipped with a temperature control device. [3] Aquarium heater according to claim 2, characterized by that the temperature control device is arranged within the part of the heater housing (2, 3) forming the connection space (3). [4] Aquarium heater according to one of claims 1 to 3, characterized bythat the at least one electrically conductive element (5, 5') is a metal element. [5] Aquarium heater according to claim 4, characterized by that at least one metal surface forming the electrically conductive element (5, 5') is vapor-deposited onto an outer surface of the glass body (2). [6] Aquarium heater according to one of claims 1 to 5, characterized by that the heater is designed as a heating rod. [7] Aquarium heater according to claim 6, characterized by that the glass body (2) of the heating housing (2, 3) is a cylindrical glass bulb. [8] Aquarium heater according to claim 6 or 7, characterized bythat on the outside of the glass body (2) of the heater housing (2, 3) a metal strip forming the electrically conductive element (5, 5') is vapor-deposited, which metal strip extends in a U-shape from a first longitudinal side of the heating rod in its longitudinal direction (9) and over its end (6) facing away from the connection space (3) to a second longitudinal side opposite the first longitudinal side. [9] Aquarium heater according to claim 6 or 7, characterized by that a metal strip forming the electrically conductive element (5, 5') is vapor-deposited on the outside of the glass body (2), which metal strip extends spirally around the glass body (2) in the longitudinal direction (9) of the heating rod. [10] Aquarium heater according to one of claims 1 to 7, characterized by that the at least one electrically conductive element (5, 5') is formed by a metal mesh surrounding the glass body (2) of the heater housing (2, 3). [11] Aquarium heater according to one of claims 1 to 7, characterized by that at least one strip-shaped or rod-shaped metal element extending along the glass body (2) of the heater housing (2, 3) protrudes from the connection space, through which the at least one electrically conductive element (5, 5') is formed. [12] Aquarium heater according to one of claims 1 to 11, characterized by that the heater housing (2, 3) in the area of the connection space (3) is made of plastic or of a rubber-like polymer or of a cast resin.

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