EP1408524A1 - Thermal fuse for a heating apparatus and heating apparatus - Google Patents

Abstract

The device has two contacts (19) and a connecting bridge (22) which forms a connection from the heating device to a power supply (20). The connecting bridge is firmly held by solder to the contacts to prevent it moving away due to the force of gravity. The softening point of the solder is set so that it softens when the heating device reaches a certain temperature. An Independent claim is included for a heating device.

Description

Field of application and state of the art

The invention relates to a safety device for a heating device with the features of the preamble of claim 1 and a Heating device with such a safety device.

It is known that some heating devices, for example for kettles, to be provided with a fuse. This is to prevent that in the event of overheating, damage or worse, for example a fire that can be caused. such Fuses are in heat-conducting contact with the heating device arranged. A heat dissolving or electrical Contact, for example in the form of a withdrawing Soldering tin trace is intended as the actual securing element.

It is also possible to use bimetal switches. With these reversible overload protection can be achieved.

The problem with known fuses is that a high one Technical and assembly effort to implement the protection is necessary to cope with the high thermal rates of increase Heating elements, in particular low-mass thick-film heating elements, to secure if there is no heat consumption. No such Existing heat loss can be, for example, a dry run Be a kettle. In an emergency, the heater or basic insulation will be destroyed.

Task and solution

The present invention has for its object a safety device for a heating device and one provided with it To create a heater with which the problems of the prior art Technology can be avoided, especially one that responds very quickly Safety device for thermal protection of a Heating device can be created.

This task is solved by a safety device with the Features of claim 1 and a heating device with the features of claim 8. Advantageous and preferred embodiments the invention are the subject of further claims and are in following explained in more detail. The wording of the claims is by express Reference made to the content of the description.

According to the safety device has two contacts and a connecting bridge, the connecting bridge being electrical is conductive and a connection of the heating device to a power or Energy supply forms. Furthermore, the connecting bridge is on the two contacts mechanically and electrically attached. Fasteners are provided for this purpose, their fastening or Fastening effect above or when a certain limit is exceeded Temperature dissolves.

The safety device is also on the heating device arranged that the fasteners and / or the connecting bridge have a heat-conducting connection with the heating device. It is further provided according to the invention that the connecting bridge held in this way by the fastening means on the contacts will prevent gravity from moving away. This means that the connecting bridge is only secured by the attachment is held to the contacts with the fastening means. triggers If one or both of the attachments are open, the connecting bridge moves away from the contacts or falls off. This can achieved that no separate force, such as spring force, needs to be provided. It will be the existing one Gravity, which also acts on such a connecting bridge, be sufficient Utzt.

Such a safety device for a Heating device can be used, the so-called "overhead installation" is mounted. This means that below the facility the Security device is present and due to this arrangement Connection bridge easily from the contacts and thus from the heater can drop out or come off.

The fasteners can be different. For example it is possible to use a solder or tin. The contacts, in particular also the connecting bridge can be metallic or metal parts or also have ceramic components. So soldering is special advantageously possible. In particular, the fasteners from the Combination of the contacts with a solder exist. It is further possible to use a conductive adhesive that works on a particular Temperature dissolves or at least softens.

Due to the material composition of such a solder, solder or conductive adhesive, its softening point can be set. So it is possible that with a predetermined assignment of the attachment of the Connection bridge on the contacts to the heating device or the Heat generation a softening of the solder and thus a loosening of the connecting bridge at a certain temperature of the heater he follows.

In an advantageous embodiment of the invention, the connecting bridge consist of or have a metal part. It can be provided that the connecting bridge between the Connections with the contacts to the outside is insulated. Such Insulation should be temperature resistant. Here are some examples Ceramic and glass coatings. Except for the Areas of the connecting bridge directly assigned to the contacts cover their entire surface. It is also possible to use the connecting bridge trained ceramic or with ceramic parts manufacture. So it can be isolating itself.

Movement due to gravity can be essentially one vertically downward fall of the connecting bridge his. In one embodiment of the invention, it can be provided that the connecting bridge when loosening the fasteners on the contacts has a tilting moment with respect to at least one contact. Particularly preferably, a tilting moment arises in relation to both contacts, so that when the connection is released, the connecting bridge solves even stronger and faster with this tipping moment. So it interrupts the electrical connection even faster and thus the Power supply. This is especially the case when fixing with solder from Advantage. With a straight connecting bridge it can quite possibly occur that through the normal liability due to Adhesion even of the liquid or softened solder the connecting bridge is held. The connection bridge can be tipped here reliably disconnect the connection.

For this purpose it can advantageously be provided that the center of gravity of the connecting bridge outside the line connecting the two Contacts. This is how a tilting moment is built up. The advantage is Center of gravity in a horizontal direction outside and to the side such a connecting line. A possible form for a connecting bridge is a single or multiple spiral U shape. With such a U-shape, with an attachment to the two free ends takes place, an aforementioned tilting moment can also advantageously be generated become.

A heating device for combination with a aforementioned safety device can have a support and a heating element. in the The safety device can be used as intended be arranged thereon such that the fastening means and / or the connecting bridge in a thermally conductive connection stand with the heater. In particular, a thermally conductive Connect to the heating element itself.

For this purpose, the securing device can be fastened to the carrier, preferably with the smallest possible distance. For one thing a manageable unit provided. Furthermore, one good heat conduction achieved. After all, temperatures are at which preferred fasteners, such as solders, are heated, already critical for many heating devices.

As stated above, the security device, especially with the Connecting bridge, seen in the direction of gravity below the heating device or the heating element.

Furthermore, the connecting bridge can be provided in the direction of gravity seen deeper than the contacts or below the contacts to arrange. The contacts can be flat and essentially run in a horizontal plane. In particular, the Contact surface run in a horizontal plane. It is also possible also the connecting bridge essentially in a horizontal Level.

The heating device can be designed such that the heating element is arranged on a flat support of the heating device. Contacts for the heating element can be found on the underside of the heating device be provided. The term bottom refers to the later installation position of the heating device. The heating element can on the one hand be provided on the top of the carrier. Here are Vias possible. The heating element on the is advantageous Bottom arranged. This is for example with kettles like has previously been performed, often the case.

The heating element can be insulated from the outside. Furthermore, can be provided be that the heating element and the connecting bridge cross or overlap. There should be insulation in between be arranged. The insulation is advantageously flat, the surface should be at least as large as that of the connecting bridge or like the projection of the connecting bridge onto the heating element. The Insulation is also advantageously applied firmly to the heating element, for example as one of the aforementioned ceramic or glass coatings.

Furthermore, it is possible to heat the heating element in a coating process to apply as a layer on the carrier. A particularly preferred one Possibility is a thick layer on an insulating carrier. The insulation can be achieved by a glass or ceramic surface become.

In a further embodiment of the invention, it is possible to use the connections to the contacts as resistance, for example as Resistance tracks. This can cause the heater to operate normally already preheating the attachment to the contacts become. Such a safety device can open faster react to overheating.

In a similar way it is possible to use the connecting bridge as a resistor train. It can advantageously have a certain temperature coefficient of resistance have such that they too ensures preheating of the fastening.

These and other features go beyond the claims from the description and the drawings, the individual Features individually or in groups in the form of sub-combinations in one embodiment of the invention and others Areas to be realized and advantageous as well as protectable Can represent designs for which protection is claimed here becomes. The division of the application into individual sections and Subheadings limit those made under each Statements not in their general validity.

Brief description of the drawings

Fig. 1

einen Schnitt durch eine Ausführung einer erfindungsgemäßen Heizeinrichtung mit einer erfindungsgemäßen Sicherungseinrichtung,

Fig. 2

eine Draufsicht auf eine alternative Ausführung einer Heizungs- und Sicherungseinrichtung,

Fig. 3

einen Schnitt durch die Ausführung aus Fig. 2 und

Fig. 4

eine weitere Ausführung einer Heizungs- und Sicherungseinrichtung in Draufsicht.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. The drawings show:

Fig. 1

2 shows a section through an embodiment of a heating device according to the invention with a safety device according to the invention,

Fig. 2

a plan view of an alternative embodiment of a heating and safety device,

Fig. 3

a section through the embodiment of Fig. 2 and

Fig. 4

a further embodiment of a heating and securing device in plan view.

Detailed description of the exemplary embodiments

1 shows an embodiment of a heating device according to the invention 11 shown in section. This is just like the other figures Drawing to understand schematically and is intended to serve the principle of the invention to explain in different versions.

A ceramic carrier 12 has a plurality of heating conductors on its upper side 16 13 on. The heating conductor 13 can run in any path as it is known per se from the prior art. For example, you can be applied in thick film technology. The heating conductor 13 and a the surrounding area of the top 16 of the ceramic carrier 12 is with insulation 14. This can be a layer of glass, for example or the like.

In particular, the insulation 14 of the heating conductor 13 has the top The advantage that electrical insulation is ensured on the one hand. Of the insulation 14 can also be used in a Heating device 11 in a kettle or similar device, which directly in with food or other media Can come into contact, shield the heating conductor 13.

On an underside 17 of the ceramic carrier 12 is a fuse 18, in in this case a thermal fuse according to the present invention, appropriate. The fuse 18 has two spaced solder contacts 19, which are applied to the underside 17. The solder contacts 19 in turn have contact leads 20. The electrical line over the contact lead 20 should be secured with the fuse 18 and be interrupted in an emergency.

For this purpose, a connecting bridge 22 is provided on the solder contacts 19. This is soldered to the solder contacts 19 with solder. It connects the Contact leads 20. The connecting bridge is in a very simple design 22 made of conductive, in particular easily solderable, metal manufactured.

If the heating device 11 or the ceramic carrier 12 become too hot, for example due to excessive power consumption of the heating plate 13 or for example, boiling empty a kettle with insufficient Heat dissipation, so also the solder contacts 19. To for this purpose, as shown in Fig. 1, they can be directly opposite a heating conductor 13 and only separated by the ceramic support 12.

The heating of the solder contacts 19 causes a certain amount a softening of the solder with which the connecting bridge 22 is fastened is. The connecting bridge can then be used with the solder softened 22 pulled down by gravity, i.e. from the solder contacts 19 away. If the contact leads 20 in the Energy supply for the heating conductor 13 are, the heating conductor of separated from the energy supply. This corresponds to the basic principle a thermal fuse with interruption.

For this purpose it is provided that the heating device 11 approximately as in FIG 1 is installed. This means that the connecting bridge 22 down from the solder contacts 19, so the Following gravity, must be able to fall. This doesn't basically mean that it must be arranged below the heating conductor 13. she can also be arranged to the side of it. Basically, it is only important that when the solder connection of the connection bridge is softened 22 to the solder contacts 19 the connecting bridge loosens.

2 shows a further embodiment of the invention with a heating device 111 shown. This can also on an underside 117 of an insulating Carrier are arranged. The illustration in Fig. 2 is one Top view, for example from below.

An elongated heating conductor 113 is provided. This is on his right end via a connection field 125 with a contact lead 120 connected. This lower contact lead 120 opens into a solder contact 119. Another solder contact is on the other side of the heating conductor 113 119 arranged in the form of a field. This is again with one Contact lead 120 connected, which for example to a power supply is led.

There is a connecting bridge between the solder contacts 119 122. It is advantageously soldered to the solder contacts 119, as before has been described. Alternatively, gluing would be possible.

A solder with a precisely defined melting point is preferred as the solder used. This melting point or a resulting softening result in connection with the weight of the connecting bridge or their necessary holding force in the installed state Tripping temperature of the fuse used as a thermal fuse 18th

Via the connecting bridge 122, which in turn is electrically conductive and for example, consist of metal or have a metal core can, the heating conductor 113 can be supplied with electrical energy. Since the connecting bridge 122 crosses the heating conductor 113, there is in between an insulating layer 124 is provided. For example, it can be glass or ceramic.

In this version of a fuse 118 are once through the Heating conductor 113 heats the solder contacts 119 and thus the solder. Of further, however, especially the connecting bridge 122 is heated, which crosses the heating conductor 113. Their warming also contributes to Heating and possibly softening the solder at the solder contacts 119 at, which speeds up this process.

Instead of an insulating layer 124, a connecting bridge 122 can also be used used, at least in the area in which they are Heating conductor 113 bridges, is itself electrically isolated.

From the sectional view in FIG. 3 along the heating conductor 113 can also be recognized how close the connecting bridge 122 to the Heating conductors 113, separated by the insulating layer 124, runs.

Basically, according to the invention, a simple connection bridge Metal piece can be used. It is also possible to use an electric conductive material with a precisely defined or desired Select conductivity. This can have the consequence that the Current flow for energy supply to the heating conductor via the connecting bridge the connecting bridge has already been preheated to a certain temperature becomes. This temperature then prevails approximately at the Solder contacts. This allows the fuse to trip even faster with preheated solder and faster reaching of the softening point can be achieved.

4 is a third embodiment of a heating device according to the invention 211 shown with a fuse 218. Here are heating conductors 213 intended. While the explanations according to Figures 1 to 3 each provide the connecting bridge in the supply line to the heating conductor, can with this version the fuse or the connection to Bridge can be provided in the course of the heating conductor itself. This would be with simple modification also in the embodiments according to the figures 1 to 3 possible.

The ends of the heating conductors 213 are connected to connection fields 225. These are in turn connected to solder contacts 219 via contact lead 220 connected or made in one piece. At the solder contacts 219 attached a connecting bridge 222 by solder.

This special embodiment of the connecting bridge 222 is approximately reversed U-shaped. Legs 228 extend from a base 227. The Ends of the legs 228, opposite the base 227 are with the Solder contacts 219 soldered. Taking into account that the device 4 is installed upside down, ie with the underside 217 downwards, the following advantages result from such a training of Connection bridge 222.

If the solder that connects the connecting bridge 222 to the solder contacts 219 connects, soft, in principle it dissolves and does not become absolutely liquid, but at least viscous. However, this still means not automatically that the connecting bridge by gravity drops. The adhesive force of the softened liquid solder can do this, similar to what would be the case with a drop of water. A straight connecting bridge 122, as shown, for example, in FIG. 2 if it is not difficult enough, it could still be sent to the Adhere solder contacts 119. It would even be about the liquid solder given the electrical connection.

In contrast, with the connecting bridge 222 according to FIG. 4, it is obvious that when the solder softens at the solder contacts 219, the weight the base 227 levered off the connecting bridge, so to speak. In order to can have a liquid-based adhesive force even with light connecting bridges be overcome.

As an alternative to a U-shaped connection bridge, for example can be provided that this is simple on one side passed over the line between the solder contacts. It so it almost depends on the center of gravity of the connecting bridge lies outside the connecting line between the solder contacts.

As has already been stated, the aforementioned design options can be used the invention, in particular the illustrated Embodiments in Figures 1 to 4, vary widely. Design options can be the carrier 12, the type and Form of the heating conductor 13, the type of electrical interconnection with the fuse 18, the solder contacts 19 and the shape of the connecting bridge 22 and their connection to the solder contacts 19 relate. Likewise, the use of conductive adhesives, which is also the Have softening properties at a certain temperature, possible. For those skilled in the art, these variations are in view of the however, the above statements are obvious.

Claims (15)

Safety device (18, 118, 218) for a heating device (11, 111, 211), the heating device having a support (12, 112) and a heating element (13, 113, 213) with: two contacts (19, 119, 219) and a connecting bridge (22, 122, 222) which is electrically conductive and forms a connection of the heating device to an energy supply (20), wherein the connecting bridge is mechanically fastened to both contacts (19, 119, 219) in an electrically conductive manner by fastening means, the fastening of which dissolves above a certain temperature, the securing device (18, 118, 218) being thus attached to the heating device (11, 111, 211 ) it is arranged that the fastening means are in heat-conducting connection with the heating device,
characterized in that
the connecting bridge (22, 122, 222) is held by the fastening means on the contacts (19, 119, 219) against moving away due to gravity. Securing device according to claim 1, characterized in that the fastening means for fastening the connecting bridge (22, 122, 222) to the contacts (19, 119, 219) are solder, the contacts and the connecting bridge preferably being metallic. Safety device according to claim 2, characterized in that the material composition of the solder makes it possible to set its softening point such that, given a predetermined assignment of the fastening to the heating device (11, 111, 211), the heating device softens at a certain temperature. Safety device according to claim 2, characterized in that the connecting bridge (22, 122, 222) consists of a metal part, it being preferably insulated from the outside between connections with the contacts (19, 119, 219), in particular with temperature-resistant insulation, preferably a layer of ceramic or glass. Safety device according to one of the preceding claims, characterized in that the connecting bridge (222) is designed in such a way that when the attachment to the contacts (19, 119, 219) is released, a tilting moment arises with respect to at least one contact, preferably with respect to both contacts. Safety device according to claim 5, characterized in that the center of gravity of the connecting bridge (22) lies outside a connecting line between the two contacts (19, 119, 219), preferably in a horizontal direction outside and to the side of the connecting line. Safety device according to one of the preceding claims, characterized in that the connecting bridge (22) has a single or multiple U-shape. Heating device (11, 111, 211) which has a support (12, 112, 212) and a heating element (13, 113, 213) with a safety device (18, 118, 218) according to one of the preceding Claims, the safety device in the intended Use of the heating device in this way on the heating device is arranged that the fastening means, in particular the connecting bridge (22, 122, 222), in thermally conductive connection with of the heating device (11, 111, 211), in particular the heating element (13, 113, 213). Heating device according to claim 8, characterized in that the securing device (18, 118, 218) is fastened to the carrier (12, 112, 212), preferably with the smallest possible distance from it. Heating device according to claim 8 or claim 9, characterized in that the securing device (18, 118, 218), in particular the connecting bridge (22, 122, 222), is arranged below the heating device (11, 111, 211), preferably in the direction of gravity below the heating element (13, 113, 213). Heating device according to one of claims 8 to 10, characterized in that the connecting bridge (22, 122, 222), viewed in the direction of gravity, is arranged below the contacts (19, 119, 219), the contacts preferably being flat and essentially horizontal Run level, and in particular the connecting bridge runs essentially in a horizontal plane. Heating element according to one of claims 8 to 11, characterized in that the heating element (13, 113, 213) is arranged on a flat carrier (12, 112, 212) and contacts (19, 119, 219) on the underside (17, 117, 217), based on the later installation, wherein the heating element is preferably arranged on the underside. Heating device according to one of claims 8 to 12, characterized in that the heating element (13, 113, 213) is insulated, the heating element and connecting bridge (22, 122, 222) preferably crossing with an insulation (14, 114, 214) arranged therebetween ), the insulation (14, 114, 214) preferably being firmly applied to the heating element (13, 113, 213) and being flat. Heating device according to one of claims 8 to 13, characterized in that the connections to the contacts (19, 119, 219) are designed as a resistor, which causes the attachment to the contacts to be preheated in normal operation. Heating device according to one of claims 8 to 14, characterized in that the connecting bridge (22, 122, 222) is designed as a resistor, wherein it preferably has a specific temperature coefficient of resistance depending on the temperature.

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