LU92823B1 - PORTABLE INCINERATOR FOR GARDEN WASTE - Google Patents

Abstract

The invention consists of a portable apparatus (2) adapted to the combustion of garden waste (5), comprising a hearth (4) intended to be fed with said waste; The apparatus further comprises an external combustion engine (6) thermally coupled to the furnace, for generating mechanical energy from the waste heat of combustion, and an electric generator (8) coupled to the engine an external combustion, capable of transforming the mechanical energy produced by said engine into electricity. The external combustion engine (6) comprises at least one external hot source zone (16), the combustion chamber being configured to transfer the waste heat of combustion at said hot source external zone (s).

Description

Description

PORTABLE INCINERATOR FOR GARDEN WASTE

TECHNICAL FIELD [0001] The invention relates to the field of apparatus adapted to the combustion of waste of the biomass type with combustion heat recovery. More particularly the invention relates to portable devices for use in a home garden.

PRIOR ART J00021 Patent document EP2 405 108A1 discloses a plant fuel incinerator of the biomass type with cogeneration. The incinerator comprises a device for producing electricity from the heat produced by the combustion, the device comprising a hot air micro turbine operating on a Brayton type thermodynamic cycle for an energy production up to 1 MW. The device further comprises a heat exchanger for heating the water of an external plant. The incinerator is interesting in that it can be small. However, the cogeneration solutions selected are of the industrial type for the production of larger models, which has an impact on the cost of the incinerator.

[00031] US Patent 5,347,035 discloses a portable device adapted to the combustion of garden waste including a fireplace to be fed by the waste. The apparatus comprises an enclosure forming the focus and including orifices, an outer wall of the form of a barrel; the space between the enclosure and the outer wall is for the air supply of the fireplace. The incinerator further comprises a frame for securing the enclosure and the outer wall; the chassis includes handles for moving the device. The incinerator also includes a hood configured to supply air to the fireplace and block the projection of sparks. The device is interesting in that it is portable format for easy use in a residential garden. It is however limited to the combustion of waste without recovery of combustion heat. Summary of the invention

TECHNICAL PROBLEM [0004] The purpose of the invention is to propose a solution that overcomes at least one of the drawbacks of the state of the art, in particular of the above-mentioned state of the art. More particularly, the invention aims to provide a portable device solution that is suitable for the combustion of garden waste of the biomass type with heat recovery of combustion in electricity and which is simple concept.

TECHNICAL SOLUTION [0005] The subject of the invention is a portable apparatus adapted to the combustion of garden waste, comprising a hearth intended to be fed with said waste; remarkable in that it further comprises an external combustion engine thermally coupled to the furnace, for producing mechanical energy from the heat of combustion of the waste, and an electric generator coupled to the external combustion engine , able to transform the mechanical energy produced by said motor into electricity. Garden waste is of the biomass type, it can include wood in branches or stems, forest waste, preferably organic waste, pine cones.

According to an advantageous embodiment of the invention, the external combustion engine comprises at least one external zone with a hot source, the hearth being configured to transfer the combustion heat of the waste at said hot source external zone or zones. .

According to an advantageous embodiment of the invention, the external combustion engine is a Stirling type engine comprising one or more cylinders each forming an external cylinder head, and one or more hot source external zones, said or each of said outer cylinder heads comprising a hot source outer zone, the focus being configured to transfer heat of combustion of the waste at said at least one outer cylinder head.

According to an advantageous embodiment of the invention, the Stirling engine is of a power less than 10kW, preferably less than 5kW, more preferably still less than 3kW.

According to an advantageous embodiment of the invention, the external combustion engine comprises at least one external zone with a hot source, the hearth comprising an air circulation system configured to supply the combustion chamber and / or to transfer the combustion chamber. heat of combustion of the waste at the external hot source zone or zones.

According to an advantageous embodiment of the invention, the air circulation system comprises an intake air duct with air intake orifices located on one or more sections of said duct, said or each of said sections being adjacent to a cylinder head.

According to an advantageous embodiment of the invention, the air circulation system further comprises a pulsed air duct comprising orifices for distributing air into the furnace, said dispensing orifices being connected to one or several sections of said pipe.

According to an advantageous embodiment of the invention the air circulation system comprises at least one air circulation fan and preferably an electronic manager connected to the fan (s) to control the air flow of said or at least one of said fans.

According to an advantageous embodiment of the invention, the air distribution system comprises a first fan connected to an intake air pipe and a second fan connected to a forced air pipe.

According to an advantageous embodiment of the invention, the apparatus is configured to perform a scrubbing of the suction air duct during maintenance phases, the electronic manager being able to reverse the flow of air in the pipe. of air sucked during said phases.

According to an advantageous embodiment of the invention, the apparatus comprises a temperature probe of the focus and / or cylinder heads connected to the electronic manager of the fan or fans.

According to an advantageous embodiment of the invention, the external combustion engine comprises at least one external zone with a hot source, the hearth comprising a bottom intended to receive the waste, said bottom being configured to transfer the heat of combustion of the waste. at the external hot source zone or zones.

According to an advantageous embodiment of the invention, the Stirling engine comprises a motor shaft and a front face opposite said shaft, said front face including the outer cylinder head or heads, the focus comprising a linked transfer enclosure hermetically to said end face at the periphery of said at least one outer cylinder head. Hermetically means airtight.

According to an advantageous embodiment of the invention the transfer chamber comprises a mat of refractory material, preferably made of concrete, covering the front face of the engine at the periphery of the cylinder head or heads, and an inner wall adhering to said mattress at the periphery of said one or more cylinder heads. The adherent inner wall is a wall extending transversely to the front face and comprising a portion adhering to the mattress. Adherent means that the inner wall and the mattress are tightly sealed.

According to an advantageous embodiment of the invention, the or each of the sections of the forced air pipe forms a loop backed to the inner wall.

According to an advantageous embodiment of the invention, the inner wall of the fireplace comprises orifices connected to the air distribution orifices.

According to an advantageous embodiment of the invention, the inner wall is made of iron or iron alloy.

According to an advantageous embodiment of the invention, the bottom intended to receive the waste form a plate connected to the inner wall and passing through the remote transfer chamber of the mattress refractory material, said plate comprising transfer ports of heat of combustion of the waste, and / or, one or more portions forming a cavity covering the or each of the cylinder heads, said or each of said portions comprising one or more heat transfer orifices. The bottom surface of the bottom plate forms the concave surface of the cavities.

According to an advantageous embodiment of the invention, the bottom for receiving the waste forms a grid.

According to an advantageous embodiment of the invention, the apparatus extends in a vertical main direction in the normal position of use and comprises rolling means, preferably wheels, located at the foot of the apparatus, the engine and the generator being located in the lower part of the apparatus, the hearth being located vertically above and connected to said engine.

According to an advantageous embodiment of the invention, the front face extends in a horizontal mean plane, the inner wall of the enclosure comprising a lower portion, preferably of cylindrical shape, with a lower edge resting on said face. front, and an upper portion connected to said portion and comprising a cover openable at its upper end, said upper portion being funnel-shaped. The openable lid includes at least one opening for extracting combustion fumes.

According to an advantageous embodiment of the invention, the lower edge of the inner wall is in contact with the mattress of refractory material, said contact forming an airtight connection.

According to an advantageous embodiment of the invention, the lower edge of the inner wall adheres to the mattress of refractory material by adhesive means and / or by the force of gravity exerted on said wall.

According to an advantageous embodiment of the invention, the bottom wall is of polygonal or cylindrical horizontal section.

According to an advantageous embodiment of the invention, the apparatus comprises means for interrupting the power supply of the fans in case of opening of the openable lid.

According to an advantageous embodiment of the invention, the cavity forming portion or portions are made of copper alloy or aluminum alloy.

According to an advantageous embodiment of the invention, the apparatus further comprises a water heating pipe with an inlet and an outlet intended to be connected to an external circuit comprising a pump, said pipe comprising at least an internal section at the hearth.

According to an advantageous embodiment of the invention, the inner portion of the water heating pipe is adjacent to the inner wall of the hearth.

According to a simplified embodiment of the invention, the inner portion of the water heating pipe extends in a spiral and is supported on the front face of the engine at the periphery of the cylinder heads so as to form a portion of the hearth of the hearth.

According to an advantageous embodiment of the invention, the generator is a DC generator, the apparatus further comprising a rechargeable battery adapted to be connected to the generator and for powering the engine at startup, an electrical outlet for an external AC power supply and an AC converter connected between said generator and said socket.

According to an advantageous embodiment of the invention, the apparatus comprises an outer wall vis-à-vis the inner wall, said outer wall preferably being integrally bonded to said inner wall.

According to an advantageous embodiment of the invention, the apparatus comprises an outer member vis-à-vis the inner wall, said outer member being intended to insulate heat said inner wall.

According to an advantageous embodiment of the invention, the apparatus comprises a frame, the wheels, the engine and the generator being mounted to said frame.

According to an advantageous embodiment of the invention, the fan or at least one of the fans is mounted outside the frame.

Advantages of the invention [0039] The measures of the invention are interesting in that the portable apparatus adapted for the combustion of garden waste is configured to recover the heat of combustion in electricity and is of simple concept.

Indeed, the portable device comprises a combustion chamber, an external combustion engine coupled to the fireplace and an electric generator, the thermal coupling is generally summed up to have the engine near the combustion chamber which makes the achievement otherwise economical . In a particular embodiment of the invention where the apparatus comprises an air circulation system for increasing the temperature of the hearth and / or a water heating circuit, the apparatus has, in addition, an advantageous yield.

Brief description of the drawings

Figure 1 is a vertical sectional view of a portable device adapted to the combustion of garden waste according to the invention and in a particular embodiment;

Figure 2 is a perspective view of the engine of the apparatus of Figure 1;

Figure 3 is a vertical sectional view of a portable apparatus adapted to the combustion of garden waste in an alternative embodiment;

DESCRIPTION OF AN EMBODIMENT [0040] FIGS. 1 and 2 illustrate the portable device adapted to the combustion of garden waste 2 according to the invention in a particular embodiment. Figure 3 illustrates the portable device adapted to the combustion of garden waste according to the invention in an alternative embodiment. The reference numbers of FIGS. 1 and 2 are used in FIG. 3 for the identical or corresponding elements, these numbers however being increased by 100 for the alternative embodiment illustrated in FIG. 3. However, specific reference numbers are used to the specific elements of the alternative embodiment.

Figure 1 is a vertical sectional view of a portable device 2 adapted to the combustion of garden waste according to the invention and in a particular embodiment. The apparatus comprises a hearth 4 that can be manually fed with waste 5, an external combustion engine 6 thermally coupled to the hearth to produce mechanical energy from the waste heat of combustion, and a generator 8 electric coupled to the external combustion engine to transform the mechanical energy produced by the engine into electricity. In particular, the generator is DC. The apparatus further includes a rechargeable battery 10 connected to the generator that can power the engine at startup. In this case, the apparatus also comprises an AC converter 12 connected to the generator and an electrical outlet 14 connected to the converter for an external AC power supply.

The external combustion engine 6 comprises one or more external zones 16 with a hot source. These external hot source zones are intended to be heated from outside the engine and the furnace 4 is configured to transfer the waste heat of combustion at these hot source zones 16. In the particular embodiment of the invention here shown, the external combustion engine 6, is a Stirling type motor generally known to those skilled in the art. The Stirling engine comprises one or more engine cylinders, in this case four, each of which forms an outer cylinder head 16. Each of the outer engine cylinder heads comprises a hot source zone of the engine. The hearth is in this case configured to transfer the waste heat of combustion to the outer cylinder heads 16 of the engine 6.

The apparatus 2 extends in a vertical main direction when in the normal position of use, it comprises wheels 24 located at the base of the apparatus, the engine and the generator are located in the lower part 26 of the unit and the fireplace is located vertically above the engine and connected with the engine. The Stirling engine comprises a downwardly directed motor shaft and a front face 20 opposite the shaft. The outer cylinder heads 16 are located on this front face. In particular, the front face of the motor extends in a horizontal mean plane and is oriented upwards, the cylinder heads being able to extend vertically.

The furnace comprises a transfer chamber 22 which is hermetically connected to the front face 20 of the engine at the periphery of the outer cylindrical heads 16. This measure of the invention is advantageous for promoting the transfer of heat of combustion on the cylinder heads. In particular, the transfer chamber 22 comprises a mat of refractory material 32, preferably made of concrete, which covers the front face of the engine at the periphery of the outer cylinder heads 16, and an inner wall 28 which adheres to the mattress 32 periphery of the outer cylinder heads. It should be noted that in addition to its hot-source zones, the Stirling engine comprises inside the envelope one or more internal zones with a cold source which are themselves cooled by internal means of the engine, for example by nitrogen. It can be seen in the image that the inner wall 28 of the enclosure comprises a lower portion 29 with a lower edge 30 which bears on the front face and a funnel-shaped upper portion 31 connected to the lower portion 29 and which includes an openable lid 36 at its upper end. The lid 36 comprises in this case an opening 39 for the evacuation of the waste combustion fumes. The funnel portion 31 of the inner wall is favorable to increase the amount of waste that can be put into the device. The inner wall 28 may be of polygonal or cylindrical horizontal section, it may be of iron alloy. In particular, the lower portion 29 of the inner wall may be of cylindrical shape. In this case, the lower edge 30 in contact with the mattress made of refractory material can adhere by the force of gravity to the mattress made of refractory material 32. This measure is advantageous for making an airtight connection economically. It can be seen that in the embodiment presented here the waste 5 is directly deposited on the mattress of refractory material 32 as well as on and between the cylinder heads 16 of the engine.

In the embodiment shown here the apparatus comprises an air circulation system 38 configured to supply the combustion chamber 4 with oxidant and to transfer the heat of the combustion of waste to the outer heads of cylinders 16. air circulation system comprises in this case a forced air pipe 40 for supplying combustion in the home; the forced air duct comprises air distribution orifices 42 in the furnace. The pulsed air duct comprises in this case one or more sections 44 leaned against the inner wall 28 and comprising the dispensing orifices 42 which face corresponding orifices in the inner wall 28. A section 44 is shown in FIG. image, the system comprises in this case an additional section 44 which is not shown. This measure is interesting to promote the combustion of waste. In another embodiment, the sections of the forced air pipe may be located inside the inner wall. The air circulation system also comprises a suction air duct 46 with sections 48 comprising air suction ports 50; these sections are adjacent to the external cylinder heads 16. This measurement is advantageous for promoting the transfer of heat at the outer cylinder heads, the warmer lighter air having a natural tendency to rise, the air suction at the level of the cylinder heads promotes that warm air can be maintained in the lower part of the hearth. It can be seen in the image that the sections 48 with the suction ports extend over the concrete mat 32 and the suction ports are oriented vertically. This representation does not limit the invention. The air circulation system 38 finally comprises a first fan 52 connected to the forced air pipe 40 and a second fan 54 connected to the suction air duct 46 and an electronic manager 56 connected to each of the fans way to control the forced air flow and the intake air flow. The fans and the manager can be powered by the battery. Alternatively, the circulation system may comprise a single fan and the circulation system may be configured so that the air pulsed in the corresponding pipe generates the air sucked into the corresponding pipe, this type of configuration being known to the skilled in the art. The apparatus 2 may comprise a temperature probe of the cylinder heads or the hearth connected to the electronic fan manager as an input of the air circulation system. The fans are shown inside the unit. This does not limit the invention.

The apparatus, in the embodiment presented here, further comprises a pipe for heating water 58 with an inlet 60 and an outlet 62 intended to be connected to an external water circuit comprising a pump . The water heating pipe 58 comprises a section 64 at the hearth. The section may extend spirally along the inner wall 28 of the hearth. This measure of the invention is interesting for recovering the waste heat of combustion for heating water and in addition to the production of electricity.

It can be seen in the embodiment of the apparatus here presented that the apparatus 2 further comprises an outer wall 66 extending along the inner wall 28 of the hearth. This wall may be thermally insulated from the inner wall by an insulating material 67 located between said wall and the inner wall 28 of the hearth. This outer wall 66 extends in this case also vis-à-vis the engine. The apparatus comprises a chassis 68 connected, in this case solidarily, to the outer wall 66 and on which are mounted the wheels 24, the engine 6, the generator 8. This embodiment however does not limit the invention. Fans in particular are schematically represented on the image and their respective size is actually generally larger.

Figure 2 is a perspective view from above of the apparatus 2 according to the invention at the outer heads of cylinders 16 of the Stirling engine 6. It can be seen the front face 20 (in broken lines) of the engine extending horizontally when the appliance is in the normal operating position; the front face 20 has four outer cylinder heads 16. The front face is in this case covered with the mat of refractory material 32 at the periphery of the outer cylinder heads as introduced in connection with Figure 1. It can be seen the conduct of pulsed air 40, the suction air duct 46 and the pipe for heating water 58. The sections 44 of the forced air duct 40 with the dispensing orifices 42 form two circular loops 70 and 70 'superimposed and at a distance from each other. This measure is interesting for distributing the air drawn at different levels of the home. The sections 48 of the suction air duct 46 with the air suction ports 50 are deposited on the concrete layer and each bypass an outer cylinder head, these sections 48 are separated in this case into two portions of the cylinder. suction around each party so as to form a suction ring 72 around each head. This measure is favorable to the efficient transfer of heat at each of the outer cylinder heads. Finally, it is possible to see the section 64 of the pipe for heating water 58 extending in this case spirally around the periphery of the cylinder heads 16. The internal wall of the hearth shown in relation to FIG. represented on the image. In a simplified embodiment of the invention, not shown, the spiral section of the pipe for heating water can form a portion of the chamber 22 of the fireplace; the spiral section may then be contiguous turns for airtightness and adhere to the concrete mattress 32. This measurement is interesting for example for the realization of an entry-level model of the apparatus, [0049] ] It should be noted that the Stirling 6 engine is here represented with four cylinder heads 16, this does not limit the invention, the engine may comprise a single cylinder. It should also be noted that the technology of a Stirling type external combustion engine is not described in detail because it must be known to those skilled in the art.

Figure 3 is a vertical sectional view of a device 102 according to the invention in an alternative embodiment. This embodiment is an alternative of the embodiment shown in connection with Figures 1 and 2 in the general sense where the apparatus comprises an external combustion engine 106 with at least one hot source zone 116 and the hearth comprises a bottom 180 for receiving the waste 105, the bottom being configured to transfer the combustion heat of the waste to the level of the external hot source zone or zones. In particular, the external combustion engine is a Stirling engine 106 with outer cylinder heads 116, these heads each forming a hot source zone, and the bottom for receiving the waste form a plate 180 connected to the inner wall 128 and passing through the transfer chamber 122 away from the mattress of refractory material 132. The bottom can also be made under the farm gate. The inner wall 128 and the motor 106 are here partially represented. The bottom plate 180 can be seen extending in a horizontal plane "L" horizontal, it can be made of iron alloy, for example cast iron or steel. The plate 180 promotes heat transfer on the outer cylinder heads in that it includes heat transfer holes 182 and portions 184 forming cavities overlying the outer cylinder heads. These portions may be reported on the plate 180 and they themselves comprise 185 heat transfer orifices. The lower surface 188 of the bottom plate forming the concave surface 188 of the cavities can be seen. The portions 184 of the plate covering the heads may be of copper alloy or aluminum alloy. This measure of the invention is interesting for promoting heat radiation on the cylinder heads of the engine. In this case, the portions project from the bottom surface 188. In a variation of the alternative embodiment (not shown), the portions may form bosses at the upper surface of the bottom. In this variation, the outer cylinder heads comprise a free end located above the average plane "L" of the bottom. We can also see the internal section 184 of the water heating pipe which is leaned against the cylindrical lower portion of the inner wall 128 and below the average level "L" of the bottom plate 180. Cola limit however not the invention, the inner section or sections of the water heating pipe may, in an alternative embodiment, be located inside the inner wall and / or above the level of the bottom plate even on the funnel portion (not shown), With respect to the airflow system T38, it can be seen that the air distribution ports 142 of the forced air line are located above the baseplate. Distribution ports may also be below the bottom plate. Arrows in the drawing indicate the flow of air exiting through the orifices 142 of the forced air line. The orifices 182 of the perforated plate 180 allow that the hot air of the hearth can go below the plate, the suction orifices 150 adjacent to the external cylinder heads of the motor generating a depression under the plate when the air duct sucked is active. Arrows in the drawing indicate the flow of air entering through the orifices 150 in the intake air line.

Claims (14)

1. Portable apparatus (2; 102) adapted to the combustion of garden waste, comprising a hearth (4; 104) intended to be fed with said waste; characterized in that it comprises, in addition: - a combustion engine external device (6; 106) thermally coupled to the furnace (4; 104), for generating mechanical energy from the heat of combustion of the waste; - an electric generator (8) coupled to the external combustion engine, suitable for converting the mechanical energy produced by said motor into electricity and - rolling means (2.4), preferably wheels, located at the base of the apparatus, said apparatus extending in a vertical main direction in the normal position of the engine (6; 106) and the generator (8) being located in its lower part, the furnace (4; 104) being located vertically above and connected to said engine, Portable apparatus (2; 102) according to claim 1, characterized in that the external combustion engine (8; 108) comprises at least one external hot-source zone (18, 118), the focal point (4: 104). being configured to transfer the waste heat of combustion (5; 105) to said hot source external zone (s). Portable apparatus (2; 102) according to claim 1, characterized in that the external combustion engine (8; 106) is a Stirling type engine comprising one or more cylinders each forming an outer cylinder head (18; and one or more hot source outer zones, said or each of said outer cylinder heads including a hot source outer zone, the focus (4; 104) being configured to transfer waste heat of combustion (5; 105) at said one or more outer cylinder heads. Portable apparatus (2; 102) according to one of claims 1 and 3, characterized in that the external combustion engine (8; 108) comprises at least one external hot-source xone (18,118). comprising an air circulation system (38; 138) configured to supply the firebox (4; 104) with oxidant and / or to transfer waste heat of combustion to the at least one hot source external area (16; 116). Portable apparatus (2; 102) according to claims 3 and 4, characterized in that the air circulation system (38; 138) comprises an intake air duct (46) with suction ports (50; 150) of air located on one or more sections (48) of said pipe, said or each of said sections being adjacent to a cylinder head (16, 116). Portable apparatus (2; 102) according to claim 5, characterized in that the air circulation system (38) further comprises a forced air pipe (40) having orifices for distributing the air in the fireplace, said dispensing orifices (42; 142) being connected to one or more sections (44) of said duct. 7. Portable apparatus (2; 102) according to one of claims 5 and 6, characterized in that the air circulation system (38) comprises at least one air circulation fan (52, 54) and preferentially an electronic manager (56) connected to the fan (s) for controlling the air flow rate of said or at least one of said fans. Portable apparatus (102) according to claim 1 or one of claims 3 to 7, characterized in that the external combustion engine (106) comprises at least one external hot-source zone (116), the hearth comprising a bottom (180) for receiving the waste, said bottom being configured to transfer the combustion heat of the waste to the external hot source area or zones (116). 9. Apparatus (2; 102) according to claim 3 or one of claims 5 to 7, characterized in that the Stirling motor (6; 106) comprises a drive shaft (7) and a front face (20) at opposite said shaft, said front face including the outer cylinder head or heads (16; 116), the focus comprising a transfer housing (22; 122) hermetically connected to said end face peripherally of said one or more outer cylinder heads (16; 116). 10. Portable apparatus (2; 102) according to claim 9, characterized in that the transfer chamber comprises a mat of refractory material (32; 132), preferably made of concrete, covering the end face (20) of the engine at the periphery. the one or more cylinder heads (16; 116), and an inner wall adhered to said mat on the periphery of said one or more cylinder heads (16; 116). 11. Apparatus (102) according to claims 8 and 10, characterized in that the bottom for receiving the waste form a plate (180) connected to the inner wall (128) and passing through the remote transfer chamber (122). a mat of refractory material (132), said plate including waste heat transfer holes (182), and / or one or more portions (184) forming a cavity overlying the one or each of the outer cylinder heads ( 116), said or each of said portions comprising one or more heat transfer orifices (185). Portable apparatus (2; 102) according to claim 10, characterized in that the end face (20) extends in a horizontal mean plane (L), the inner wall (28; lower portion (29), preferably of cylindrical shape, with a lower edge (30) bearing on said front face, and an upper portion (31) connected to said portion and comprising an openable lid (36) at its upper end, said upper portion being funnel-shaped. Portable apparatus (2; 102) according to one of claims 1 to 12, characterized in that it further comprises a water heating pipe (58) with an inlet (60) and an outlet ( 62) for connection to an external circuit comprising a pump, said conduit comprising at least one inner section (64; 164) at the focus (4; 104). 14. portable device (2; 102) according to one of claims 1 to 13, characterized in that the generator (8) is a DC generator, the apparatus further comprising a rechargeable battery (10) apt to be connected to the generator and for powering the motor (6; 106) at startup, an electrical socket (14) for an external AC power supply and an AC converter (12) connected between said generator and said outlet.