US20090123884A1

US20090123884A1 - Burner Device

Info

Publication number: US20090123884A1
Application number: US11/990,320
Authority: US
Inventors: Elmar Stumpf
Original assignee: BSH Bosch und Siemens Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2005-08-08
Filing date: 2006-07-04
Publication date: 2009-05-14
Also published as: EP1915571A1; CN101238332A; DE102005037365A1; ZA200801124B; WO2007017316A1; BRPI0615170A2

Abstract

A burner device for operation with a fuel that is liquid at room temperature, especially a vegetable oil, including an evaporator system for evaporating the liquid fuel, and a nozzle for ejecting and for igniting the evaporated fuel under the effect of flame. The burner also includes a heat conducting sheet which at least partially surrounds the evaporator system.

Description

The invention relates to a burner device for operation with a fuel that is liquid at room temperature, especially with a vegetable oil, with an evaporator system for evaporation of the liquid fuel, a nozzle for ejecting and for igniting the evaporated fuel.
A burner is described in publication DE 101 61 154 A1 which is operated at room temperature with a liquid fuel. For example vegetable oil for cooking is burned with this burner. To enable the vegetable oil to be ignited, the burner features an evaporator. If this evaporator is heated, the liquid vegetable oil changes to its gas phase and rises up in the evaporator. The gaseous vegetable oil exits via a nozzle from the evaporator as a stream of vegetable oil gas, hits a baffle device and is ignited. The open flame produced by the combustion of the vegetable oil is surrounded by a heat conducting sheet which serves to protect the user of the burner from being burned by the open flame. For an operator of a burner it is advantageous for the burner to have the greatest possible efficiency. In this case the efficiency of a burner can be defined by a comparatively small amount of fuel transmitting a high level of heat during combustion to a cooking vessel placed over the burner.
The object of the present invention therefore lies in providing a burner device which guarantees reliable operation.
The object is achieved by a burner device in accordance with the features of claim 1.
The burner device can include an evaporation system for evaporation of fuel which is liquid at room temperature, and a cylindrical heat conducting sheet which at least partly surrounds the evaporation system, with the heat conducting sheet featuring in its jacket at least one air supply opening.
By the inclusion of at least one air supply opening in the jacket of heat conducting sheet it is possible to design the heat conducting sheet to be long enough to enclose the entire evaporator without this impeding the supply of oxygen for the combustion of the vegetable oil. This means that the inventive heat conducting sheet differs from the heat conducting sheet from publication DE 101 61 154 A1 which only covers the upper part of the evaporation system. The additional length of the inventive heat conducting sheet allows better control of the flame to an object to be heated up, for example a cooking vessel. Air eddies which reduce the heat transmission from the burner to the heated up object can be suppressed in this way.
The heat conducting sheet can be heat-insulating. This reduces a transfer of heat from the evaporator to the area around the sides of the burner device. In addition the design protects the user from accidental contact with the burner device.
A further inventive solution to the task is a burner device comprising an evaporation system for evaporation of a fuel which is liquid at room temperature, especially of a vegetable oil, and a cylindrical heat conducting sheet which at least partly surrounds the evaporator device, with the heat conducting sheet comprising an inner wall and an outer wall, and with a gap being embodied between the inner wall and the outer wall. The gap ensures a draft of air if required. This type of heat conducting sheet also allows the air stream to be controlled over the entire length of the evaporator.
In this case the inner wall and/or the outer wall can feature at least one cutout on a face of the heat conducting sheet. This provides further options for control of the air stream around the evaporator.
Preferably the outer wall is heat-insulating. This makes it possible to prevent burning injuries if the heat conducting sheet is touched. In addition a temperature increase within the heat conducting sheet is guaranteed in this way since the heat insulation means that less heat is emitted to the area to the sides of the burner device.
The inner wall can likewise be heat-insulating. This makes a preheating of the air draft as it flows through the air gap possible.

The invention is described below on the basis of the figures. The figures show:

FIG. 1: in a perspective view a vegetable oil cooker;

FIG. 2: an evaporator with vapor exit nozzle;

FIG. 3: in accordance with a first exemplary embodiment, a double-wall heat conducting sheet for the evaporator; and

FIG. 4: in accordance with a second exemplary embodiment, a double-wall heat conducting sheet for the evaporator.

FIG. 1 shows a perspective view a vegetable oil cooker. The vegetable oil cooker features a burner base 1. The burner base I consists of three legs 3 which meet to form a star shape. The legs 3 are embodied as U-profile rails open at the bottom. At the free ends of the legs 3 pot support ribs 5 extend vertically upwards to hold a cooking container. An evaporation system 7 is arranged centrally on burner base 1. In accordance with FIG. 1 the evaporation system 7 features a hollow cylindrical heat conducting sheet 9. The heat conducting sheet 9 delimits a combustion chamber 10, in which the evaporator tube 11, which is shown in FIG. 2 in detail, is arranged.
In accordance with FIG. 2 the evaporator 11 is embodied as an evaporator tube with an evaporator tube filament 13. The two tube ends 15 and 17 of the evaporator tube are connected to a distribution pedestal 19. The two tube ends 15, 17 of the evaporator 11 are connected via the distribution pedestal 19 to a fuel supply line 20. This is connected to an underside of the distribution base 19. The distribution pedestal 19 is surrounded by a fuel tray 21. The fuel tray 21 can be filled with a fuel. This is used for pre-heating the liquid fuel which is fed from the fuel feed line 20 into the tube ends 15, 17 of the evaporator tube 11. The fuel tray 21 is connected in one piece to the distributor pedestal 19 of the evaporator 11.
The evaporator 11 is supported via the fuel tray 21 on a cylindrical protective plate 23 which is shown in FIG. 1. In this case the fuel tray 21 has a step 22 around its outside which rests on the protective cylinder 23. In accordance with FIG. 1 the heat conducting sheet 9 is supported with its lower edge on a shoulder 33 of the fuel tray 21.
In accordance with FIG. 2 an upwards-pointing nozzle 25 is incorporated into the evaporator tube 11 in the bottom section of the tube filament 13. The nozzle 25 lies opposite a baffle plate 7 which is attached to an upper section of the tube filament 13. When vapor or gas exits from the nozzle 25 the flow of vapor is braked by the baffle plate 27. This means that the time for which the vapor remains in the combustion space between the nozzle 25 and the baffle plate 27 is increased. This improves the mixing of the vapor with the surrounding air into a combustible gas/air mixture.
The heat produced from the combustion is discharged upwards in the direction towards the cooking container by means of the cylindrical heat conducting sheet 9.
As shown in FIG. 1 air supply openings 29, 31 are embodied in the heat conducting sheet 9. Secondary air, i.e. combustion air, flows from the surroundings into the inside of the heat conducting sheet below the baffle plate 27 through the air supply openings 29, 31.
The air supply openings 29, 31 are divided up into first air supply openings 31 and second air supply openings 29. The combustion chamber formed below the baffle plate 27 is supplied via the first air supply openings 31 with secondary air S whereas the air supply openings 29 provided at the lower edge of the heat conducting sheet supply air to a fuel located in the fuel tray 21.
For operation of the vegetable oil cooker in accordance with FIG. 1 the fuel tray 21 is first filled with a fuel and this is ignited by a user. Subsequently a rotary knob 35 arranged on a leg 3 of the burner base 1 is actuated to open the fuel feed line 20. This causes liquid fuel to flow towards the evaporator 11. As a result of the preheating of the tube ends 15, 17 of the evaporator 11 by the fuel burning in the fuel tray 21 the liquid fuel vaporizes in the tube ends 15, 17. The vaporized fuel emerges via the nozzle 25. The stream of vapor emerging from the nozzle 25 is slowed down by the baffle plate 27. This brings about a mixing into a combustible gas/air mixture with increased time below the baffle plate 27, where a constant flame is created.
FIG. 3 shows a variation in which the heat conducting sheet 9 is a double-wall design with an inner wall 37 and an outer wall 39 shown by a dashed line. The inner wall 37 is separated by an annular gap 42 from the outer wall 39 of the heat conducting sheet. In this design the secondary air S flows over the face of the annular gap 41 which is open at the top along the inner wall 37 to the air supply openings 29 in the lower area of the inner wall 37. The secondary air S is thereby pre-heated before arriving in the combustion space through the air supply openings 29. The preheated secondary air contributes to a significantly more stable flame profile and thereby to a reliable burner operation.
FIG. 4 presents a further variation of the double-wall heat conducting sheet 9. By contrast with FIG. 3 the outer wall 39 of the double-wall heat conducting sheet is not supported on the protective plate 23 but is separated from it via distance pieces not shown through a space z. A convection flow 43 is thereby created in the annular gap 41. This is supplied with an inflow of ambient air via the space z. The convection flow 43 is directed onto the cooking container placed on the cooking vessel supports 13. This means that the heating power of the vegetable oil cooker available for the cooking container increases. Not only the convection flow created within the inner wall 37, but in addition the convection flow 43 is also available for heating up the cooking container.
In FIG. 1 the heat conducting sheet 9 has a height which corresponds at least to the height of an associated evaporator 11 not shown in FIG. 1. The extent of the heat conducting sheet 9 is also selected so that the evaporator 11 can be easily affixed to the inside of the heat conducting sheet 9. The heat conducting sheet 9 can in this case be in the shape of a cylinder or of a prism. As can be seen from FIG. 1, the heat conducting sheet 9 features a number of openings 29, 31. In this case the height of the openings 31 is selected so that the flame arising during the combustion of the vegetable oil from the evaporator 11 can be well supplied with oxygen via the openings 31. The openings 29 in the heat conducting sheet 9 attached to the evaporator 11 are located below the openings 31. A flame in the ignition tray 21 below the evaporator 11 is to be supplied with air via the openings 29.
In FIG. 2 the heat conducting sheet 9 from FIG. 1 is attached to an evaporator 4. In this figure the evaporator 11 is only partly visible since it is covered by the heat conducting sheet 9.
The attachment of the heat conducting sheet 9 to the evaporator 4 enables the so-called chimney effect of the burner to be increased. In this case the hot air from the flame of the evaporator tube rises within the heat conducting sheet 9 up to a vessel placed over the heat conducting sheet 9. The heat conducting sheet 9 suppresses possible eddies which would cause an onwards flow of the hot air into the area to the sides of the burner. This increases the transfer of heat from the flame of the evaporator 11 to the pot not shown in FIG. 2.
A further example of a heat transfer plate 9 is shown in FIG. 3. In this figure the heat transfer plate 9 is embodied as a double-wall design. It comprises a heat-insulating outer jacket 39 and a heat-conducting inner jacket 37. Embodied between the outer jacket 39 and the inner jacket 37 is an annular gap 42. A draft of air is possible between the outer jacket 39 and the inner jacket 37 by virtue of this annular gap 42.
The heat conducting sheet 9 is connected via the outer jacket 39 to the ignition tray 21. The annular gap 42 is therefore closed at the bottom. As shown by arrow S air can only be sucked in via the upper annular gap 42. In this case the induced air is preheated as it flows along the inner jacket 37. Via the openings 29 in the inner jacket 37 the preheated air will then be sucked into the inside of the inner jacket 37. The preheating of the air before induction prevents a cooling down of an evaporator 11 accommodated within the inner jacket 37. This is important in order not to cool down the evaporator 11 disproportionately.
The chimney effect causes the air in the interior of the jacket 37 to rise to the open flame of the evaporator 11. This provides the flame of the evaporator with a constant supply of oxygen. Supplying the flame with sufficient oxygen guarantees that the vegetable oil is burned as well as possible.
The heat conducting sheet 9, as already mentioned, increases the chimney effect since it prevents air eddies which would cause a reduction in the heat transfer. This guarantees a good transfer of the heat of the flame to a pot, not shown in FIG. 3, arranged above the heat conducting sheet 9.
The heat conducting sheet 9 in FIG. 4 is also embodied as a double-wall design. It features an Outer jacket 39 made from a heat-insulating material and an inner jacket 37 made from a heat-conducting and fireproof material. Between the two jackets is embodied an annular gap 41, through which an air draft between the jackets is possible. By contrast with the heat conducting sheet from FIG. 3, the heat conducting sheet here is accommodated on an evaporator 11 not shown in FIG. 4 so that a further gap z is maintained between the ignition tray 21 and the heat conducting sheet 9. Air can be induced via the gap z into the inside of the heat conducting sheet 9. As depicted by the arrows 43 in FIG. 4, the induced air then rises up inside the outer jacket. In doing so the air heats up on the inner jacket made of heat-conducting material. This leads to an additional convection flow which contributes to the heating up of a pot not shown in FIG. 4.
Via the openings 29 in the inner jacket 37 air will be sucked into the inside of the inner jacket 37. This air rises up inside the inner jacket 37 and thereby supplies the flame of the evaporator 11 with oxygen. This guarantees that gaseous vegetable oil coming out of the evaporator 11 is almost completely burned.

Claims

1-10. (canceled)

11. A burner device for operation with a fuel that is liquid at room temperature, especially a vegetable oil, the burner device comprising:

an evaporation system for evaporation of the liquid fuel;

a nozzle in fluid communication with the evaporation system for expelling and for igniting the evaporated fuel;

a baffle plate disposed in fluid communication with the. nozzle for forming a combustion space intermediate the baffle plate and the nozzle;

a fuel tray disposed in fluid communication with the nozzle, and a heat conducting sheet disposed in at least a partial surrounding relationship with the evaporation system, the heat conducting sheet having at least one air supply opening formed therein for delivering combustion air to the burner device.

12. The burner device according to claim 11 wherein the heat conducting sheet includes a first air supply opening formed therein for supplying air to a combustion space formed below the baffle plate and a second air supply opening formed therein for supplying air to a fuel located in the fuel tray.

13. The burner device according to claim 11 wherein the heat conducting sheet is formed with a first wall portion and a second wall portion spaced from the first wall portion.

14. The burner device according to claim 13 wherein the first and second wall portions are curved and second wall portion is spaced radially away from the first wall portion defining an annular air gap therebetween.

15. The burner device according to claim 14 wherein the annular gap is in fluid communication, using the air supply openings in the first wall portion, with an inner chamber defined within the curvature of the first wall portion.

16. The burner device according to claim 14 wherein the annular gap formed by the first and second wall portions of the heat conducting sheet forms an air duct.

17. The burner device according to claim 14 wherein the annular gap formed by the first and second wall portions of the heat conducting sheet is closed at one end of the first and second wall portions.

18. The burner device according to claim 13 wherein the heat conducting sheet is formed with at least one cutout on a face of at least one of the first wall portion and the second wall portion.