WO2003063256A2 - Thermoelectric generator - Google Patents

Abstract

A thermoelectric generator, comprising a kerosene lamp (10), one or more thermoelectric converters (24) which are mounted in such a way that they all fit tightly between an outer radiator (22) and an inner radiator (26), forming a unit which is supported by a duct (20) for the flow of hot gases, leading into the inner radiator (26). The thermoelectric generators (24) are semiconductors.

Description

 THERMOELECTRIC GENERATOR

The invention relates to a thermoelectric generator of the type comprising an oil lamp and a thermoelectric converter with thermocouples, the hot junctions of which are in thermal contact with the hot gases produced by the lamp when it is lit.

In a known embodiment, described in document WO00 / 08692, the thermoelectric converter comprises electrically conductive metal wires of two different natures, welded in pairs at their ends to form on one side hot junctions and on the other side cold junctions which are electrically connected in series, and it takes the form of a vertical cylinder mounted in the lamp above the flame so that the latter heats the underside of the cylinder, which comprises the hot junctions . The upper face of the cylinder comprising the cold junctions is connected by a vertical rod or tube of thermal conduction to an annular radiator which rests on the upper part of the lamp. Typically, the electrical power produced when the lamp is running is a few tenths of a watt and is used to power a transistor radio receiver built into the base of the lamp.

The present invention relates to a thermoelectric generator of this type, capable of providing a much greater electrical power, in particular of several watts, for the power supply of various electronic devices, and in particular for recharging a mobile phone of the type GSM or similar.

To this end, it proposes a ^" thermoelectric generator comprising an oil lamp, a thermoelectric converter whose hot junctions are in thermal contact via an internal radiator with the hot gases produced by the lamp and whose cold junctions are in thermal contact with the ambient atmosphere via an external radiator, characterized in that the thermoelectric converter comprises semiconductor elements clamped between the internal radiator and the external radiator and is carried by the upper end of a duct forming a chimney for the passage of hot gases mounted in the upper part of the lamp above the flame and opening into a vertical cylindrical space in which the fins of the interior radiator extend.

This configuration ensures good guidance and concentration of the hot gases produced by the lamp on the fins of the radiator associated with the hot face of the thermoelectric converter and good capture of the thermal energy of these hot gases, for the transmission of this energy to the thermoelectric converter. It also prevents any loss of heat flow to the outside and concentrates this flow on the interior radiator.

Such a converter has the advantage of providing a large electrical power, typically of several watts.

According to another characteristic of the invention, this thermoelectric converter comprises at least one parallelepipedal block clamped between the internal radiator and the external radiator, this block comprising for example semiconductor elements fixed between two alumina plates or the like

Advantageously, the two radiators are connected by fixing means of the screw-nut type associated with elastically deformable means for absorbing differential stresses of thermal expansion. These fixing means extend on either side of the converter and elements of thermally insulating material are interposed between this converter and the aforementioned fixing means, and are for example traversed by the latter.

This ensures optimal operation of the thermoelectric converter and increases its reliability and its service life. In a preferred embodiment of the invention, the thermoelectric generator comprises several thermoelectric converters arranged around the axis of the aforementioned vertical cylindrical space and mounted between the external radiator and one or more internal radiators whose fins extend in said cylindrical space.

These thermoelectric converters can be mounted electrically in series or in parallel, for powering electronic devices with relatively high electrical power.

For example, the generator according to the invention comprises two thermoelectric converters diametrically opposite with respect to the axis of the abovementioned vertical cylindrical space and mounted clamped between the external radiator and an internal radiator whose fins extend vertically in this cylindrical space .

It is thus possible to produce an electrical power of between 2 and 3 watts with a kerosene lamp of a conventional type, when the resistance of the electronic device thus supplied is approximately 3 ohms.

According to yet another characteristic of the invention, the assembly formed by the exterior and interior radiators and by the converter (s) is fitted onto a sleeve clipped or snapped onto the upper end of a lamp glass and this assembly is vertically movable relative to a fixed lamp frame for lighting the kerosene lamp.

In a particular embodiment of the invention, this assembly is advantageously guided in rotation on the frame of the lamp and is moved vertically by screwing - unscrewing around the axis of the lamp. In a preferred application, the generator according to the invention, constructed from a kerosene lamp of a conventional type, can power a radio receiver with transistors which is integrated in the base of the lamp and further comprises means of supply of a charge circuit of a mobile phone of the GSM or other type, with a regulated voltage. In other applications, the generator according to the invention can be used for the electrical supply of a microcomputer of the type portable or other electronic devices requiring an electrical power between one and a few watts for their operation.

The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly on reading the description which follows, given by way of example with reference to the appended drawings in which:

- Figure 1 is a schematic view in axial partial section of a generator according to the invention;

- Figure 2 is an enlarged view of the circled detail II of Figure 1;

- Figure 3 is a schematic top view, on a larger scale, of this generator;

- Figure 4 is a top view of the interior radiator of the generator; FIG. 5 is an enlarged view of the circled detail V of FIG. 4.

- Figures 6 and 7 are schematic views in axial section, in two perpendicular planes, of an alternative embodiment of the invention; - Figure 8 is a plan view in axial section of a converter assembly;

- Figure 9 is a top view of the converter;

- Figure 10 is a plan view of the frame of the lamp of Figures 6 and 7. In the embodiment shown in Figures 1 to 5, the thermoelectric generator according to the invention comprises an oil lamp 10 or storm lamp of a conventional type, the base 12 of which forms an oil reservoir and may include a transistor radio receiver as described in the above-mentioned document WO00 / 08692. A charging or supply circuit of an electronic device such as a mobile phone for example, is integrated in the base 12 and includes a connection connector mounted on the base. The focal point 14 of the lamp is protected by a cylindrical glass envelope 16, which rests on an annular support 18 which can be moved vertically upwards to allow the lamp to be ignited by means of a flame presented at the level of the hearth 14. On the upper part of the casing 16 is placed a vertical duct 20 optionally heat-insulated which itself carries at its upper end an assembly formed by an external radiator 22, one or more thermoelectric converters 24 and one or more interior radiators 26 and which will be described in more detail below. The conduit 20 is formed for example of two coaxial tubes 28 and

30 mounted one inside the other and separated by an annular gap filled with a thermal insulation material 32, such as glass wool or rock wool, any other refractory material and thermally insulation that can also be used. A washer 33 made of refractory material is placed on the upper end of the duct 20 and thermally insulates the latter from the above-mentioned assembly formed by the external radiator 22, the thermoelectric converter (s) 24 and the internal radiator (s) 26.

The external radiator 22 is generally annular in shape with a circular outline and comprises a cylindrical body carrying external radial fins which extend over a height greater than that of the thermoelectric converter (s) 24 to increase the surface area for exchange with the surrounding atmosphere. . To further increase this exchange surface, the fins 34 can be of generally wavy shape instead of being flat as shown in FIG. 3.

The inner cylindrical surface 36 of the radiator 22 defines a cylindrical internal space with a vertical axis which extends the duct 20 and in which the thermoelectric converter (s) 24 and the interior radiator (s) 26 are arranged. In the example shown, the cylindrical surface internal 36 of the external radiator 22 comprises two diametrically opposite flats 38, on which two vertical bosses 40 of substantially rectangular section are formed, which are support surfaces of the thermoelectric converters 24. The latter are of substantially rectangular parallelepiped shape and are clamped radially between the bosses 40 of the external radiator 22 and corresponding bosses 42 of the or internal radiators 26 by means of screw-nut systems which extend radially with respect to the vertical axis of the lamp and which are arranged above and below respectively the thermoelectric converters 24, in the upper and lower parts radiators 22 and 26. To ensure good thermal conduction, a layer of thermally conductive grease is interposed between the converters 24 and the bosses 40 and 42 of the radiators.

For example, and as shown diagrammatically in FIGS. 1 and 2, each fastening system comprises a radial screw 44 whose free end is screwed into a threaded orifice of an interior radiator 26 and whose head 46 is applied to the cylindrical wall of the external radiator 22 by means of one or more washers 48 of an elastically deformable material such as rubber or the like, for absorbing the stresses due to thermal expansion of the above-mentioned assembly.

In addition, the screws 44, four in number in the example shown, pass through elements 50 of refractory or thermally insulating material which separate them from the upper and lower ends respectively of the thermoelectric converters 24. The two radiators 26 each associated with a converter thermoelectric 24 are in this example of generally rectangular parallelepiped shape and include a base plate 52 one side of which is formed with a boss 42 above and the other side of which has fins 54 which are plane and parallel to each other and which extend vertically in the space delimited by the cylindrical internal surface 36 of the external radiator 22. As shown diagrammatically in FIG. 5, the fins 54 could be of corrugated shape to increase the surface area for exchange with the surrounding atmosphere.

As can be clearly seen in FIG. 3, the two interior radiators 26 are diametrically opposite and their fins 54 are oriented towards each other and are substantially in contact at their ends. In an alternative embodiment, the generator may include more than two thermoelectric converters 24, each converter being associated with an interior radiator whose fins are oriented radially towards the vertical axis of the exterior radiator 22. To concentrate the heat flux produced by the lamp on the internal radiators 26, the entire free space between these radiators and the internal surface 36 of the external radiator is filled with glass wool, rock wool or other refractory and thermally insulating material.

The thermoelectric converters 24 are of a commercially available type and are formed for example of bismuth telluride elements mounted on alumina wafers, the junctions of the thermocouples being on the side of the bosses 42 of the interior radiators 26 and the others on the side of the bosses 40 of the external radiator 22. A washer 60 of refractory or thermally insulating material covers the upper end of the above-mentioned assembly and separates it from a ring 62 for attaching the lamp, which can be fixed by screwing or clipping on the upper end of the external radiator 22.

The operation of this generator obviously follows from the above.

When the lamp is on, the hot gases produced by the combustion of petroleum pass through the heat-insulating duct 20 and come into contact with the fins 54 of the interior radiators 26. The thermal energy captured by these fins is transmitted by the plates 52 and the bosses 42 of the interior radiators at the hot junctions of the thermoelectric converters 24. The cold junctions of these converters are at contact of the ambient air via the external radiator 22. Most of the thermal energy conveyed by the hot gases is captured by the internal radiators, and the temperature of the hot gases at the outlet is only 60- 80 ° C approximately. The electrical power produced in steady state by the integrated circuit in the base of the lamp is of the order of 2.5 watts when the electronic device supplied has an internal resistance of the order of 3 ohms, the supply voltage regulated for example being 3 volts, 6 volts or possibly 12 volts. The assembly formed by the interior and exterior radiators and by the thermoelectric converters 24 is carried by the conduit 20, which is itself carried by the glass envelope 16 of the lamp. The lifting of this envelope for lighting the lamp therefore results in a vertical displacement of the conduit 20 and of the aforementioned assembly. Optionally, means for guiding this assembly can be provided on the lateral arms 64 of the lamp as well as elastic return means, such as springs, making it possible to bring the assembly formed by the external and internal radiators and by the converters thermoelectric in their operating position shown in Figure 1. It may also be advantageous to fix all the radiators and converters on the conduit 20, by means of vertical threaded rods which extend in the space formed between the external radiator and the interior radiator filled with insulating material. Nuts are screwed onto the upper free ends of these rods and bear on the upper insulating washer 60. The heads of the threaded rods are for example applied to the inner tube 30 of the conduit 20 which, for reasons of absorption of thermal expansion differential, is preferably mechanically independent of the outer conduit 28.

The exterior 22 and interior 26 radiators are for example made of aluminum, for reasons of lightness. They can however be made of any heat conductive material and preferably inexpensive.

The interior radiators 26 can be in the shape of a rectangular parallelepiped as shown, or else in a semi-cylindrical shape with radial or parallel fins between them.

In the variant embodiment shown in FIGS. 6 to 10, the kerosene lamp comprises a reservoir 12, a burner 14 and a lamp glass 16 of a standard type, which are mounted in a frame formed by two half-shells 70 substantially identical, made of any suitable rigid material and which are fixed to each other on either side of the reservoir 12 and of the glass 16 by clipping or elastic snap-fastening, by gluing, by welding or by any other suitable means.

These half-shells 70 comprise a base 72 in the form of a dome, intended to cover the reservoir 12 and comprising in the lower part means 74 for receiving and holding an apparatus such as a radio receiver with transistors for example, and arm 76 extending upwards and connecting the base 72 to a cylindrical upper part 78 intended to receive the thermoelectric converter.

As in the previous embodiment, this converter essentially comprises an external radiator 24, an internal radiator 26 and one or more conversion blocks 24 formed of semiconductor elements 80 mounted between two alumina plates 82, these blocks 24 being tightened radially between the internal radiator 26 and the external radiator 22. As in the previous embodiment, the internal radiator 26 is of rectangular parallelepiped shape and comprises fins carried by base plates on which the conversion blocks 24 are supported. This internal radiator 26 defines a vertical duct for the passage of hot gases which is connected by a metal sleeve 84 of a standard type to the aforementioned lamp glass 16. The metal sleeve 84 is removably fixed, preferably by clipping or snap-fastening elastic, on the upper end of the lamp glass 16 and for this purpose comprises clip tabs 86 oriented downwards and which engage inside the glass 16 to lock on an upper internal rim thereof to secure the sleeve 84 on the glass 16. The lower part of the interior radiator 26 is itself fitted into the upper end of the sleeve 84, this upper end having a cross-sectional shape, for example square, adapted to that of the lower end of the radiator 26.

A helical spring 88 is mounted around the upper part of the sleeve 84 and is supported on an internal shoulder of the cylindrical body of the external radiator 22 to allow a small vertical movement of the converter relative to the sleeve 84, the return force of this spring 88 tending to separate from one another the sleeve 84 and the converter formed by the two radiators and the conversion blocks. A cover 90 covers the upper end of the converter and is fixed to the external radiator 22 by screws 92 while being kept at a certain distance above the converter, for example of the order of one or two centimeters.

This cover 90 comprises a solid central part 94 which can serve as a support for a container to be heated, a cylindrical skirt 96 at its outer periphery, which is oriented downwards and which surrounds with play the upper part of the fins 34 of the external radiator of the converter, and hot gas outlet openings 98 which are formed between the solid central part 94 and the outer cylindrical skirt 96. Two diametrically opposite tabs 100 are further formed on the cover 90 and include openings 102 for passage and attachment of a ring or handle for carrying the lamp.

The skirt 96 of the cover 90 is intended to cooperate with the upper cylindrical part 78 of the lamp chassis for the installation of the thermoelectric converter in the chassis and for the use of the kerosene lamp. Preferably, this cooperation is done by screwing - unscrewing around the axis of the lamp.

For this, one can form a thread on the upper part 78 of the lamp frame and on the cylindrical skirt 96 of the converter cover or, more simply and more economically as shown in Figures 8 and 10, one can only form two diametrically opposite helical grooves 104 in the upper part 78 of the lamp frame and two pins 108 on the cylindrical skirt 96 of the cover 90 of the converter, these pins being intended to be received and guided in the grooves 104 mentioned above.

This allows in particular mounting and actuation of the quarter-turn type.

For this purpose, each groove 104 of the upper cylindrical part

78 of the lamp frame comprises two vertical ends 106 oriented upwards at its ends, one of which opens onto the upper edge 107 of the upper cylindrical part 78 of the frame to allow the fitting of a stud 108 of the skirt 96 and the other of which defines a service position for the assembly formed by the thermoelectric converter and the lamp glass 16. In the example shown, the cylindrical skirt 96 of the cover 90 externally surrounds the upper cylindrical part 78 of the chassis of the lamp and the grooves 104 are formed in the outer cylindrical surface of this part 78. This arrangement could of course be reversed, the cylindrical skirt 96 of the cover then coming inside the upper cylindrical part 78 of the lamp frame .

For the assembly and use of this lamp, we ^" proceed as follows:

The chassis being assembled on the tank 12, the lamp glass 16 is placed on the chassis, an annular part 110 of which surrounds the burner 14 and is intended to support a lower rim of the lamp glass 16. The thermoelectric converter was previously assembled by mounting the conversion blocks between the external radiator 22 and the internal radiator 26 and the sleeve 84 was put in place on this converter by engagement of its upper end on the lower end of the internal radiator 26 .

The assembly can then be introduced into the upper cylindrical part 78 of the lamp frame, the pins 108 of the skirt 96 of the cover 90 being engaged in the upper vertical ends 106 of the grooves 104, then the converter is rotated over approximately a quarter turn relative to the lamp frame, which moves the pins

106 in the grooves 104 to the lower ends 106 thereof.

When the thermoelectric converter is in this lowest position relative to the lamp frame, the spring 88 associated with the sleeve 84 is compressed and tends to push up the converter, the pins 108 of which move upward in the vertical ends lower 106 grooves 104. The converter is then locked in rotation on the lamp frame. During this mounting, the lower end of the sleeve 84 is fixed by clipping or snapping onto the upper edge of the lamp glass 16. As a variant, it is of course possible to fix the lamp glass 16 by clipping or snapping onto the the lower end of the sleeve 84 before fixing this sleeve on the lower part of the interior radiator 26 of the converter. The converter-lamp glass assembly is then placed on the lamp frame as previously indicated. To ignite the lamp, the thermoelectric converter is rotated through the cover 90 on ^"the frame of the lamp in the direction opposite to the assembly, which moves the pins 108 into the grooves 104 upward and causes the converter and thermoelectric and the lamp glass 16 in the upper position In this position, the lower edge of the lamp glass 16 is located above the burner 14, which allows the lamp to be ignited. The converter-lamp glass assembly is then rotated by rotating the cover 90 relative to the lamp frame, to bring this assembly back to the lower position shown in FIGS. 6 and 7.

In the embodiment which has just been described, the lamp glass 16 is removably attached to the thermoelectric converter and the latter is supported and guided in rotation and in translation by the frame 70 of the lamp.

The electrical connections between the thermoelectric converter and the devices to be supplied may include electrical conductors housed in the arms 76 of the chassis and arriving in the lower part of the base 72 for the electric supply of a transistor radio receiver housed in this lower part or well for connection to a connector mounted in a suitable housing 112 (Figure 7) formed by the base 72 of the chassis.

Claims

1 - Thermoelectric generator, comprising a kerosene lamp (10), a thermoelectric converter whose hot junctions are in thermal contact via an internal radiator (26) with the hot gases produced by the lamp and whose cold junctions are in thermal contact with the ambient atmosphere via an external radiator (22), characterized in that the thermoelectric converter (24) comprises semiconductor elements clamped between the internal radiator (26) and the external radiator (22) and is carried by the upper end of a duct (20) forming a chimney for the passage of hot gases mounted in the upper part of the lamp above the flame and opening into a vertical cylindrical space in which extend fins (54) of the interior radiator. 2 - Generator according to claim 1, characterized in that the interior (26) and exterior (22) radiators are connected by clamping means of the screw-nut type associated with elastically deformable means for absorbing differential stresses of thermal expansion . 3 - Generator according to claim 2, characterized in that said clamping means extend on either side of the converter (24). 4 - Generator according to claim 2 or 3, characterized in that elements (50) of thermally insulating material are interposed between the converter (24) and the clamping means (44), and are crossed by the latter. 5 - Generator according to one of the preceding claims, characterized in that it comprises two thermoelectric converters (24) diametrically opposite with respect to the axis of the above-mentioned vertical cylindrical space and each mounted clamped between the external radiator (22) and the interior radiator (26) whose fins extend vertically in said cylindrical space. 6 - Generator according to claim 5, characterized in that the fins (54) of the interior radiators (26) are parallel to each other. 7 - Generator according to one of the preceding claims, characterized in that the space between the interior radiator (s) (26) and the exterior radiator (22) is filled with a refractory and thermally insulating material. 8 - Generator according to claims 1, 5, 6, or 7, characterized in that the thermoelectric converter is removably fixed, for example by elastic snap-fastening, on the end of a lamp glass (16) and is mounted axially displaceable on the fixed frame (70) of the lamp between a low service position and a high ignition position. 9 - Generator according to claim 8, characterized in that the converter is displaceable by screwing on the upper part (78) of the frame (70). 10 - Generator according to claim 8, characterized in that the converter is guided on the upper part (78) of the chassis by means of ramps or helical grooves (104). 11 - Generator according to one of claims 8 to 10, characterized in that the lower part of the interior radiator (26) is fitted into the upper end of a sleeve (84) whose lower end has lugs (86 ) clicks into place on the lamp glass (16). 12 - Generator according to one of claims 8 to 11, characterized in that the converter is equipped with an upper cover (90) having openings (98) for passage of hot gases and a cylindrical skirt (96) for guiding the upper part (78) of the lamp frame. 13 - Generator according to one of claims 8 to 12, characterized in that the frame (70) of the lamp is formed of two half-shells nested and fixed one on the other on either side of the tank (12) and the lamp glass (16).