GB1573980A

GB1573980A - Portable mains electric immersion heater

Info

Publication number: GB1573980A
Application number: GB3050077A
Authority: GB
Original assignee: BAHLMANN KG
Current assignee: BAHLMANN KG
Priority date: 1977-03-24
Filing date: 1977-07-20
Publication date: 1980-09-03
Also published as: DE7709242U1

Description

(54) PORTABLE MAINS ELECTRIC IMMERSION HEATER (71) We, G. BAHLMANN KG GmbH & BR< Co., a Kommanditgesellschaft organised and existing under the laws of the Federal Republic of Germany, of 5885 Schalksmuhle 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a portable mains electric immersion heater.

Heaters of this kind have been proposed for heating a small quantity of water in a vessel, such as a cup, so that a beverage can be infused, the heater having a metal sheathed resistance heating element and a handle to receive the ends of the element.

In such previously proposed heaters however there is the danger that the element will engage a table-top, window-sill or other surface in which the heater is placed after use and cause at laest superficial burns and, in serious cases, even a fire. This danger is considerably increased if the immersion heating device is accidentally left on, i.e. is not switched off by disconnecting it from the electrical supply after use.

According to the invention there is provided a portable mains electric immersion heater comprising a metal sheathed heating element with a resistive core and having a convoluted portion and two arms, a handle which receives the ends of the arms of the element and a protective support member comprising a disc of metal or plastics mateterial through which the arms of the element extend whereby if the heater is laid on a surface it can rest on the handle and the edge of the disc with the element spaced from the surface.

Since, when the heater is rested on a surface, it only contacts the surface with the free end of the handle and the edge of the disc, the spacing between the lowest part of the element and the surface eliminates the dangers described above.

Preferably the disc is circular, is located on an opposite side of the centre of gravity of the heater to the side thereof at which the handle is located and has a claw member which engages one of the arms of the element and retains the disc in position on the element.

The claw member is preferably one of an opposed pair of claw members each formed from a portion pressed out from the circular disc and bent. This has the advantage that the protective support member and its mounting can be produced from the same material. The pair of opposed claw members extend from a middle crosspiece of the disc that extends between two apertures in the disc and are bent around respective ones of the arms of the element.

The protective support may in addition include at least two generally U-shaped hoops surrounding the convoluted portion of the element in a basket-like manner and attached to the disc, the hoops having inwardly bent ends secured to the disc and their middle regions crossed-over one another and connected together at the crossover position.

Of the two hoops, at least one can be provided with shaped feet portions in its middle region.

In order to reduce heat transfer from the heater via the protective support member to the resting surface, it is recommended to provide on both sides, in addition to said apertures, further small apertures or cuts in the disc.

A heat-sensitive switch or fuse may be accommodated in an inner space of the handle and be connected between one end of the resistive core and one of the wires of a mains connection lead. Thus in manufacture the ends of the arms of the element, the electrical connections, and the heat-sensi tive switch or fuse can be located in an internal space of the handle, which is then filled with a casting composition.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Fig. 1 is a front view of a first embodi ment of a portable immersion heater according to the invention; Fig. 2 is a fragmentary view of the im mersion heater of Fig. 1, showing electrical connections and with the handle removed; Fig. 3 is a sectional view taken on line III-III of Fig. 1; and Fig. 4 is a side view of a second embodi ment of a portable immersion heater according to the invention.

The electrical immersion heater 10 of the first embodiment is particularly suitable for household purposes and comprises a metal sheathed resistance heating element 11, a handle 12, a protective support member 13, and a mains electrical lead 14. The heating element 11 is formed by a tubular metal sheath bent to form two parallel extending arms 15, 16 joined by a convoluted portion 17, the tubular metal sheath containing an electrically resistive core 18.

As can be seen from Fig. 2, live and neutral wires 19, 20 of the mains lead 14 are joined in an electrically conducting manner to the ends of the resistive core 18 which project from the ends of the tubular sheath of the heating element 11. A heat-sensitive safety fuse 22 is inserted between the live wire 19 and the respective end 21 of the heating core 18. The safety fuse 22 prevents the heating element 11 from burning out, since it breaks the circuit in the event of overheating. The immersion heater 10 is thus unusable after melting of the safety fuse 22. If desired, instead of the safety fuse 22, other temperature-sensitive devices could be used which disconnect the current on overheating but are switched on again or can be switched on again after the temperature has fallen to a permissible value.

An earth wire 23 of the electrical lead 14 is connected to the arm 16 of the tubular metal sheath.

In the embodiment of Figs. 1 to 3, the handle 12 is formed as a bell-shaped cap of a plastics material. The ends of the arms 15, 16, the electrical connections, and the heatsensitive device 22 are accommodated in the interior 24 of the handle 12. After the handle 12 has been attached, its interior 24 is filled with a casting composition. A water-level indicator 25 is preferably embedded at the same time in the casting composition.

The protective support member 13 comprises, in the first embodiment, a circular metal disc 26. Parts are pressed out from the disc 26 and bent around to form a pair of opposed claw members 27. Two apertures 28 are thereby formed, separated by a middle crosspiece 29. Thus the claw members 27 are located in an opposed pair on this central crosspiece 29, with the opposed claw members gripping respective arms 15, 16 directly above the convoluted portion 17 like a pair of pincers. Three further, circular apertures 30 are made in each side of the disc 26, in addition to the apertures 28. The further apertures 30 on each side of the disc are adjacent to one another, the middle one of the apertures 30 being larger in diameter.

Fig. 4 shows a second embodiment of an immersion heater 10. This corresponds in its overall construction with the first embodiment, and accordingly like reference numerals will be employed for like parts. The protective support member 13 however includes in addition to the disc 26, a protective basket. For this purpose, two U-shaped hoops 31 of metal are joined to one another in a cross-over arrangement in their middle regions 32 and the free ends 33 of the hoops 31 are folded inwardly and secured to the underside of the disc 26. The middle region 32 of the hoop 31 has two shaped feet 34.

The disc 26 of the protective support member 13 could be formed of other shape, for example rectangular, preferably square.

Furthermore, the hoops 31 could be formed of wire.

WHAT WE CLAIM IS: 1. A portable mains electric immersion heater; comprising a metal sheathed heating element with a resistive core and having ,a convoluted portion and two arms, a handle which receives the ends of the arms of the element and a protective support member comprising a disc of metal or plastics material through which the arms of the element extend, whereby if the heater is laid on a surface it can rest on the handle and the edge of the disc with the element spaced from the surface.

2. A portable mains electric immersion heater according to claim 1, in which the disc is circular, is located on an opposite side of the centre of gravity of the heater to the side thereof at which the handle is located and has a claw member which engages one of the arms of the element and retains the disc in prsition on the element.

3. A portable mains electric immersion heater according to claim 2, in which the claw member is one of an opposed pair of claw members formed from a portion pressed out of the circular disc.

4. A portable mains electric immersion heater according to claim 3, in which the pair of opposed claw members extend from a middle crosspiece of the disc that extends between two apertures in the disc and are bent around respective ones of the arms of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. tive switch or fuse can be located in an internal space of the handle, which is then filled with a casting composition. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Fig. 1 is a front view of a first embodi ment of a portable immersion heater according to the invention; Fig. 2 is a fragmentary view of the im mersion heater of Fig. 1, showing electrical connections and with the handle removed; Fig. 3 is a sectional view taken on line III-III of Fig. 1; and Fig. 4 is a side view of a second embodi ment of a portable immersion heater according to the invention. The electrical immersion heater 10 of the first embodiment is particularly suitable for household purposes and comprises a metal sheathed resistance heating element 11, a handle 12, a protective support member 13, and a mains electrical lead 14. The heating element 11 is formed by a tubular metal sheath bent to form two parallel extending arms 15, 16 joined by a convoluted portion 17, the tubular metal sheath containing an electrically resistive core 18. As can be seen from Fig. 2, live and neutral wires 19, 20 of the mains lead 14 are joined in an electrically conducting manner to the ends of the resistive core 18 which project from the ends of the tubular sheath of the heating element 11. A heat-sensitive safety fuse 22 is inserted between the live wire 19 and the respective end 21 of the heating core 18. The safety fuse 22 prevents the heating element 11 from burning out, since it breaks the circuit in the event of overheating. The immersion heater 10 is thus unusable after melting of the safety fuse 22. If desired, instead of the safety fuse 22, other temperature-sensitive devices could be used which disconnect the current on overheating but are switched on again or can be switched on again after the temperature has fallen to a permissible value. An earth wire 23 of the electrical lead 14 is connected to the arm 16 of the tubular metal sheath. In the embodiment of Figs. 1 to 3, the handle 12 is formed as a bell-shaped cap of a plastics material. The ends of the arms 15, 16, the electrical connections, and the heatsensitive device 22 are accommodated in the interior 24 of the handle 12. After the handle 12 has been attached, its interior 24 is filled with a casting composition. A water-level indicator 25 is preferably embedded at the same time in the casting composition. The protective support member 13 comprises, in the first embodiment, a circular metal disc 26. Parts are pressed out from the disc 26 and bent around to form a pair of opposed claw members 27. Two apertures 28 are thereby formed, separated by a middle crosspiece 29. Thus the claw members 27 are located in an opposed pair on this central crosspiece 29, with the opposed claw members gripping respective arms 15, 16 directly above the convoluted portion 17 like a pair of pincers. Three further, circular apertures 30 are made in each side of the disc 26, in addition to the apertures 28. The further apertures 30 on each side of the disc are adjacent to one another, the middle one of the apertures 30 being larger in diameter. Fig. 4 shows a second embodiment of an immersion heater 10. This corresponds in its overall construction with the first embodiment, and accordingly like reference numerals will be employed for like parts. The protective support member 13 however includes in addition to the disc 26, a protective basket. For this purpose, two U-shaped hoops 31 of metal are joined to one another in a cross-over arrangement in their middle regions 32 and the free ends 33 of the hoops 31 are folded inwardly and secured to the underside of the disc 26. The middle region 32 of the hoop 31 has two shaped feet 34. The disc 26 of the protective support member 13 could be formed of other shape, for example rectangular, preferably square. Furthermore, the hoops 31 could be formed of wire. WHAT WE CLAIM IS:

1. A portable mains electric immersion heater; comprising a metal sheathed heating element with a resistive core and having ,a convoluted portion and two arms, a handle which receives the ends of the arms of the element and a protective support member comprising a disc of metal or plastics material through which the arms of the element extend, whereby if the heater is laid on a surface it can rest on the handle and the edge of the disc with the element spaced from the surface.

the element.

5. A portable mains electric immersion heater according to claim 4, in which, in addition to said apertures, further smaller apertures are provided in the disc.

6. A portable mains electric immersion heater according to any one of claims 1 to 5, in which, in addition to the disc, the protective support member comprises at least two generally U-shaped hoops surrounding the convoluted portion of the element in a basket-like manner and attached to the disc, the hoops having inwardly bent ends secured to the disc and their middle regions crossedover one another and connected together at the cross-over position.

7. A portable mains electric immersion heater according to claim 6, in which, of the two hoops, at least one is provided in its middle region with shaped feet.

8. A portable mains electric immersion heater according to any one of the preceding claims, including a heat-sensitive switch or fuse connected between one end of the resistance core and one of the wires of a mains connection lead, the switch or fuse being accommodated in the interior of the handle.

9. A portable mains electric immersion heater substantially as hereinbefore described and illustrated with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.