FR2570809A1 - Heating instrument with heat accumulation - Google Patents

Abstract

The invention relates to a heating instrument. It comprises an outer tubular envelope 4 surrounding an inner tubular envelope 5 and delimiting, with the latter, an annular space, two annular end pieces 6, 7 for closing the said annular space in a sealed fashion, a material which is capable of melting at a temperature greater than the ambient temperature inside the said annular space, heating means being provided in order to melt the said fusible material prior to the use of the instrument.

Description

 The present invention relates to a heating instrument with heat accumulation such as a soldering iron or a hair dryer for example.

 It is known that conventional soldering irons include a heating resistor wound around the tube which reviews the tip. An insulating material such as mica must be interposed between the tube and the heating element and interferes with the passage of heat from this resistance to the tip.

 In addition, these irons include an electrical supply cord which provides resistance which is bothersome to the user and also risks being burnt by the breakdown.

 It has already been proposed to remedy the drawbacks of the power cord, to store electrical energy in batteries, for example cadmium / nickel.

 However, these batteries are expensive, require a power supply, a medium-voltage / low-voltage transformer and a rectifier bridge for charging, and have a recharge time of several hours.

 The present invention aims to provide a heating instrument, such as a soldering iron or a hair dryer using neither power cord nor battery.

 To this end, the subject of the invention is a heating instrument, characterized in that it comprises an external tubular envelope surrounding an internal tubular envelope by delimiting with the latter an annular space, two annular end pieces for closing the baleen seals said annular space, and a fusible material at a temperature above ambient temperature inside said annular space, heating means being provided to cause the melting of said fusible material prior to the use of the instrument.

 Energy is therefore stored directly in thermal form, via the latent heat of fusion of the fusible material.

 Furthermore, the heating means may not be electrical means and are in any case independent of the instrument which is therefore autonomous.

Finally, the central space inside the internal envelope can be used for fixing a soldering iron tip, a plastic cutting tool, a pyrography or other tool, or even left free for the passage of air, in the case of a hair dryer for example
In a particular embodiment, the axial ends of the internal and external envelopes are engaged in annular sealing grooves formed in the end pieces.

 In the case where it is desired to merge the fusible material by Joule effect, said end pieces are made of an electrically insulating material or are electrically insulated from at least one of the tubular casings, said tubular casings are made of a electrically conductive material, said fusible material is a conductive material, and electrical connection means are provided for connecting said envelopes to a source of electric current.

 The electric current is therefore transmitted from one connection means to the other by means of one of the tubular casings, of the fusible material and of the other tubular casing.

 In a particular embodiment of the invention, a tubular ring is disposed between the two tubular envelopes to form an electrical resistance of predetermined value between the part of the fusible material located between the outer envelope and the ring, and the part of the fusible material located between the inner casing and the ring.

 This ring makes it possible to adjust the electrical resistance of the assembly constituted by the two tubular casings and the fusible material so as to avoid using a transformer for the heating phase of the instrument.

 The invention also relates to a charging support for a heating instrument as described above, characterized in that it comprises means of electrical supply capable of coming into electrical contact with said means of electrical connection, and a switch for closing the electrical supply circuit by cooperating with a lug secured to said heating instrument.

 Consequently, as soon as the instrument is placed on its support, the electrical supply circuit is closed by the switch and the fusible material is heated by the Joule effect. The switch prevents the circuit from being inadvertently closed on any conductive body other than the instrument.

 In another embodiment of the invention, one of the annular end pieces is arranged to form a seat for a cartridge of pressurized combustible fluid.

 In this case, the cartridge is brought into contact with this end piece so as to cause the escape of the combustible fluid which is ignited in the space inside the internal envelope and thus causes the fusion of the fusible material.

 In another embodiment, the space inside the internal envelope is arranged to receive an exothermic chemical cartridge.

 The heat released by the chemical cartridge is then directly transmitted to the fusible material via the internal envelope.

 Of course, the three embodiments of heating by Joule effect, by cartridge of combustible fluid, or by chemical cartridge, can advantageously be combined on the same device to enable it to be put into service in all situations.

 In the case where the heating device according to the invention is intended to be used as a soldering iron, preferably a fusible material will be chosen at a melting temperature between 2950C and 450 C.

A particular embodiment of the invention will now be described by way of nonlimiting example with reference to the appended schematic drawings in which
FIG. 1 is a partial view in axial section of a heating instrument according to the invention, and
- Figures 2, 3 and 4 show three possible heating modes for the device of Figure 1.

 This device has an outer casing in two parts, a part 1 surrounding the heating elements of the device while the other part 2 serves as a handle. Parts 1 and 2 are articulated around an axis 3 for reasons which will be explained below.

 An outer tubular casing 4 and an inner tubular casing 5 are mounted in two annular end pieces, namely an outer piece 6 and an inner piece 7. The pieces 6 and 7 have annular grooves 8 which ensure sealing connections between the envelopes 4 and 5 on the one hand and the parts 6 and 7 on the other.

 An annular ring 9, produced for example in a conductive material, in a porous ceramic, or in an electrically insulating synthetic material, provided with holes 10, separates the annular space between the envelopes 4 and 5 into two cavities 11 and 12.

 In the cavities 11 and 12 is placed a solid material at room temperature.

 The end pieces 6 and 7 and the internal casing 5 delimit a cylindrical conduit 13 opening out on the side of the piece 7 so as to form a seat 14 whose function will be described below.

 Finally, a lug 15 is mounted on the outer casing and an electrical contact 16, constituted for example by a bimetallic strip, electrically connects part 1 of the casing to the outer casing 4.

 The device 17 according to the invention is shown in Figure 2 provided with an electrical contact piece 18 engaged in the conduit 13, which may for example be constituted by a soldering iron failure.

 In this FIG. 2, the device 17 is about to be placed on a support generally designated by 19 and comprising two electrical contact points 20 and 21 intended to support the breakdown 18 and the casing of the device respectively. In addition, a bipolar switch 22 connected to an electric current source by a power cord 23 is provided to cooperate with the lug 15 when the instrument 17 is placed on the support 19.

When the lug engages in the switch 22, the latter closes the electrical circuit which is thus constituted by the support 20, the purlin 18, the internal casing 5, the fusible material located in the cavity 11, the ring 9, the fusible material located in the cavity 12, the outer casing 4, the blade 16, the part 1 of the casing, and the support 21.

 There is then produced an electric current which gives off by Joule effect heat in the fusible material so as to melt it. The material of the ring 9 as well as the size of the openings which are possibly made therein, are chosen so as to obtain the desired potential drop in the aforementioned circuit, so that the support 19 can be directly connected to the medium voltage. without transformer interposition.

 The bimetallic strip 16 is arranged so that, when the temperature reaches a certain threshold, it cuts this electric circuit, which ensures the operational safety of the device.

 As a variant, the bimetallic strip can be located on the support 19, for example at the level of the contacts 20 or 21.

 FIG. 3 shows that, when the casing part 2 is pivoted relative to the casing part 1, it gives access to the seat 14 on which the orifice of a cartridge 24 of pressurized combustible fluid can be applied. This fluid being released, it flows into the conduit 13 where it is ignited to cause the heating and melting of the fusible material contained in the cavities 11 and 12.

 In FIG. 4, an exothermic chemical cartridge 25 is about to be introduced into the conduit 13 to be primed there. After this priming, the cartridge 25 will give off heat which will also cause the fusible material contained in the cavities 11 and 12 to melt.

 The cartridge 25 may also include an extension forming the breakdown of the soldering iron, in order to avoid the need to replace this cartridge with an independent breakdown during use.

 The device 17 according to the invention can therefore be used even if there is no nearby electrical energy source to which to connect the support 19.

 The fusible material used in the cavities 11 and 12 is chosen so as to have a melting temperature in the desired temperature range for heating the tool inserted in the conduit 13 or the air passing through this conduit. For example, in the case of the application of this device to a soldering iron, it is possible to choose a material having a melting temperature between 2950C and 4500C, such as zinc or silver halide.

 We will preferably choose a material that does not sublime, does not present any risk of explosion or toxicity, does not react with the envelope, and does not decompose at operating temperature.

 Finally, it is also preferable to choose a fusible material having a high latent heat of fusion in order to increase the autonomy of the device.

 Of course, various variants and modifications can be made to the above description without departing from the scope or the spirit of the invention.

Claims (8)

 1. Heating instrument, characterized in that it comprises an external tubular envelope (4) surrounding an internal tubular envelope (5) delimiting with the latter an annular space, two annular end pieces (6,7) for closing dewlap sealing said annular space, a material fusible at a temperature higher than the ambient temperature inside said annular space, heating means (23,24,25) being provided to cause the melting of said fusible material beforehand use of the instrument.  2. Heating instrument according to claim 1, characterized in that said end pieces are made of an electrically insulating material or are electrically insulated from at least one of the tubular envelopes, that said envelopes are made of an electrically conductive material, that said fusible material is a conductive material, and that electrical connection means (1,16,18) are provided for connecting said envelopes to a source of electric current.  3. Heating instrument according to claim 2, characterized in that it comprises a tubular ring (9) disposed between the two tubular envelopes to form an electrical resistance of predetermined value between the part of the fusible material located between the outer envelope and the ring and the part of the fusible material located between the inner casing and the ring.  4. Charging support for a heating instrument according to any one of claims 2 and 3, characterized in that it comprises electrical supply means (20,21) capable of coming into electrical contact with said connection means electrical, and a switch (22) for closing the electrical supply circuit by cooperating with a lug (15) integral with said heating instrument.  5. Heating instrument according to any one of claims 1 to 3, characterized in that one of the annular end pieces (7) is arranged to form a seat (14) for a cartridge (24) of combustible fluid under pressure.  6. Heating instrument according to any one of claims 1 to 3 and 5, characterized in that the space inside the internal envelope is arranged to receive an exothermic chemical cartridge (25).  7. Heating instrument according to any one of claims 1 to 3, 5 and 6, characterized in that the fusible material has a melting temperature between 2950C and 4500C.  8. Heating instrument according to any one of claims 1 to 3 and 5 to 7, characterized in that the axial ends of the inner and outer envelopes are engaged in annular sealing grooves (8) formed in the pieces of extremities.