Combustion chamber configurations for vaporizer burners

Abstract

To provide a combustion chamber constitution group for carburetor burner, especially, for a fuel operation type vehicle heating device.SOLUTION: The present invention relates to a combustion chamber constitution group for carburetor burner, which includes a housing (14) comprising a peripheral wall (12) extending along a housing lengthwise axis (L) and defining a combustion chamber (18) radially outside, and a combustion chamber bottom part (16) defining the combustion chamber (18) along the axis, wherein a porous carburetor medium (30) is provided on the side (26) of the combustion chamber bottom part (16) which faces the combustion chamber (18). The porous carburetor medium (30) is curved concavely to the combustion chamber (18) on the side (32) which faces the combustion chamber (18).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a combustion chamber arrangement for a vaporizer burner, which can be used in particular in fuel-operated vehicle heating systems.

[0002] Such a combustion chamber assembly for a carburetor burner of a fuel-operated vehicle heating system is known from German Patent Application No. DE 10 2013 220 654 A1. The combustion chamber assembly includes a combustion chamber housing with a peripheral wall extending in the direction of the housing longitudinal axis and a combustion chamber bottom axially defining the combustion chamber. The bottom wall of the combustion chamber bottom provides, on its side facing the combustion chamber, a carburetor medium contact surface extending substantially perpendicular to the housing longitudinal axis. A substantially planar, porous carburetor medium is arranged on the carburetor medium contact surface, oriented substantially perpendicular to the housing longitudinal axis with its side facing the combustion chamber. A fuel supply conduit opens into the bottom wall in a radially central region, through which liquid fuel is supplied to the porous carburetor medium.

[0003] In the case of a combustion chamber assembly for a vaporizer burner of a fuel-operated vehicle heating system known from German Patent No. 10 2012 111 289, in order to achieve improved contact of the porous vaporizer medium, particularly made up of multiple layers, against the bottom wall of the combustion chamber bottom, the bottom wall is curved convexly with respect to the combustion chamber, which is axially bounded by the combustion chamber bottom in the direction of the longitudinal axis of the housing. The porous vaporizer medium, which in its basic state is essentially disk-shaped or flat, is held in its radially outer region against the radially outer region of the bottom wall, which is curved convexly with respect to the combustion chamber, so that the porous vaporizer medium also takes on a convexly curved form with respect to the combustion chamber and is therefore pressed more firmly against the convexly curved vaporizer medium contact surface of the bottom wall, especially in its radially central region.

[0004] SUMMARY OF THE INVENTION The object of the present invention is to provide a combustion chamber arrangement, in particular for a vaporizer burner for a fuel-operated vehicle heating system, which achieves improved combustion characteristics.

[0005] This problem is solved according to the present invention by a combustion chamber assembly, in particular for a carburetor burner for a fuel-operated vehicle heating device, which comprises a combustion chamber housing having a peripheral wall extending in the direction of the housing longitudinal axis and defining the combustion chamber radially outward, and a combustion chamber bottom defining the combustion chamber in the axial direction, wherein a porous carburetor medium is provided on the side of the combustion chamber bottom facing the combustion chamber, the combustion chamber assembly being characterized in that the porous carburetor medium is curved concavely relative to the combustion chamber on its side facing the combustion chamber.

[0006] The concavely curved structure of the porous carburetor medium on its side facing the combustion chamber combines various aspects that positively influence the combustion characteristics. On the one hand, in the radially outer region, there are no or few strongly embossed corners or volumes at the transition from the combustion chamber bottom to the peripheral wall, which form dead spaces where excessively high fuel concentrations occur during combustion operation, which inhibit combustion and promote the formation of deposits. On the other hand, such combustion chamber configurations are particularly suitable for mounting vehicle heating devices equipped in this way on vehicles so that the concavely curved side of the porous carburetor medium facing the combustion chamber faces vertically downward. The concavely curved structure results in the radially outer regions of the porous carburetor medium being positioned vertically further downward or providing the lowest region of the porous carburetor medium, thereby achieving gravity-assisted uniform distribution of the liquid fuel supplied to the porous carburetor medium also in the radially outer regions of the carburetor medium.

[0007] In order to be able to provide a particularly efficient radially outward uniform fuel distribution, it is proposed that the porous carburetor medium is concavely curved relative to the combustion chamber and / or that the porous carburetor medium has a substantially constant thickness.

[0008] In a radially central region, the fuel supply conduit may open into the bottom of the combustion chamber, and the porous carburetor medium may have a curved apex in the radially central region, in which case the liquid fuel can be distributed substantially uniformly within the porous carburetor medium starting from the curved apex of the carburetor medium radially outward.

[0009] In order to avoid the creation of an intermediate space between the porous carburetor medium and the bottom of the combustion chamber that would impair uniform fuel distribution, it is proposed that the bottom of the combustion chamber has a carburetor medium contact surface on its side facing the combustion chamber that is concavely curved toward the combustion chamber.

[0010] It is particularly advantageous in this case if the curved geometry of the evaporator medium contact surface substantially corresponds to the curved geometry of the porous evaporator medium on its side facing the combustion chamber.

[0011] To support the porous vaporizer medium, the combustion chamber bottom may have a bottom wall that provides at least a portion of the vaporizer medium contact surface.

[0012] In a configuration which can be realized particularly simply structurally, the bottom wall can provide substantially the entire vaporizer medium contact surface.

[0013] In order to achieve rapid and uniform distribution of the liquid fuel also in the radially outer region of the porous vaporizer medium, it is proposed that the bottom wall has a recess that is open toward the side of the bottom wall facing the combustion chamber to accommodate the porous distributor medium, and in this case, a first portion of the vaporizer medium contact surface is provided on the bottom wall and a second portion of the vaporizer medium contact surface is provided on the porous distributor medium.

[0014] In particular, when the liquid fuel is supplied to the porous carburetor medium in a radially central region, it is particularly advantageous for uniform fuel distribution if the first portion of the carburetor medium contact surface annularly surrounds the second portion of the carburetor medium contact surface and / or the porous distributor medium is arranged substantially centered relative to the housing longitudinal axis. In order to distribute the liquid fuel radially outward as quickly as possible through the porous distributor medium, it is proposed that the porous distributor medium have a higher porosity than the porous carburetor medium.

[0015] The porous disperser medium may be curved on the side opposite the vaporizer medium contact surface, in which case the curved geometry of the porous disperser medium on the side opposite the vaporizer medium contact surface substantially corresponds to the curved geometry of the porous disperser medium in the second portion of the vaporizer medium contact surface, or / and the porous disperser medium has a substantially constant thickness.

[0016] In a configuration that further supports efficient radially outward transport of liquid fuel, it is proposed that the porous distributor medium, on its side opposite the vaporizer medium abutment surface, extend substantially perpendicular to the housing longitudinal axis and / or that the porous distributor medium has a thickness that increases from the radially inner side to the radially outer side, meaning that the area of ​​the porous distributor medium through which the liquid fuel flows radially increases not only with increasing distance from the radially inner side to the radially outer side relative to the housing axis, but also with increasing thickness of the porous vaporizer medium.

[0017] To avoid heat loss, an insulating material may be arranged on the side of the bottom wall facing away from the evaporator medium contact surface.

[0018] In order to position the porous carburetor medium in a defined manner, it is proposed that the carburetor medium is fixed at its outer periphery relative to the bottom of the combustion chamber.

[0019] For this purpose, the combustion chamber bottom may have a retaining element that annularly surrounds the bottom wall, in which case the retaining element has at least one retaining protrusion that holds the porous evaporator medium against the bottom wall on its side facing the combustion chamber.

[0020] The invention further relates to a fuel-operated vehicle heating system having a burner region with a combustion chamber arrangement constructed according to the invention.

[0021] The present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a longitudinal cross-sectional view of a combustion chamber arrangement for a vaporizer burner for a fuel-operated vehicle heating system; FIG. [Figure 2] 2 is a view corresponding to FIG. 1, showing an alternative configuration of the combustion chamber arrangement; [Figure 3] 2 is a view corresponding to FIG. 1, showing an alternative configuration of the combustion chamber arrangement; [Figure 4] 2 is a view corresponding to FIG. 1, showing an alternative configuration of the combustion chamber arrangement;

[0023] The combustion chamber assembly 10 shown in longitudinal section in Fig. 1 comprises a combustion chamber housing 14 having a circumferential wall 12, which extends in the direction of the longitudinal housing axis L and is, for example, substantially cylindrical in shape. In an axial region not shown in Fig. 1, the circumferential wall 12 may be provided with a flame constriction on its inner surface. Following this flame constriction, the circumferential wall 12 may merge into a flame tube or may be connected to a flame tube formed as a separate component.

[0024] 1 is provided in its axial end region with a combustion chamber bottom generally designated 16. The combustion chamber bottom 16 defines a combustion chamber 18, which is radially bounded on the outside by the peripheral wall 12, in the direction of the longitudinal housing axis L.

[0025] The combustion chamber bottom 16 has a bottom wall 20, into whose central region 22, radially aligned with the housing longitudinal axis L, opens a fuel supply conduit 24 for supplying liquid fuel. On its side 26 facing the combustion chamber 18, the bottom wall 20 of the combustion chamber bottom 16 presents a carburetor medium contact surface 28 that is curved concavely relative to the combustion chamber 18.

[0026] A porous vaporizer medium 30 is supported in the direction of the housing longitudinal axis L on a vaporizer medium contact surface 28 of the bottom wall 20, which is curved concavely with respect to the combustion chamber 18. The porous vaporizer medium 30 may be made, for example, of a wire material, in particular a wire net, a wire knit, a wire woven, etc., and may have such a porosity that liquid fuel flowing into the porous vaporizer medium 30 from the fuel supply conduit 24 in the central region 20 is dispersed within the internal volume of the porous vaporizer medium 30 also by capillary transport and flows out of the porous vaporizer medium 30 in the form of vapor at the side 32 of the porous vaporizer medium 30 facing the combustion chamber 18.

[0027] 1 has, for example, substantially the same thickness d in all circumferential and radial regions, such that the porous carburetor medium is concavely curved in itself, and in particular also on its side 32 facing the combustion chamber 18, whereby, due to the substantially constant thickness d, the curved geometry of the porous carburetor medium 30 on its side 32 facing the combustion chamber 18 substantially corresponds to the curved geometry of the carburetor medium contact surface 28 of the combustion chamber bottom 20 on its side 26 facing the combustion chamber 18.

[0028] To keep the porous evaporator medium 30 in a defined contact state with the evaporator medium contact surface 28, a retaining element 34 is provided in the radially outer region of the combustion chamber bottom 16, annularly surrounding the bottom wall 20. The retaining element 34 may be positioned, for example, between the outer peripheral region of the bottom wall 20 and the axial end region of the peripheral wall 12, and may be stably connected to the peripheral wall 12 or the bottom wall 20 by a material bond, for example by welding or brazing. In multiple regions spaced apart from one another in the circumferential direction, the holding member 34 has holding protrusions 36 bent radially inward and toward the side 32 of the porous evaporator medium 30 facing the combustion chamber 18, and these holding protrusions 36 abut against the radially outer region of the porous evaporator medium 30 on the side 32 of the porous evaporator medium 30 facing the combustion chamber 18, thereby stably holding the evaporator medium 30 against the concavely curved evaporator medium abutment surface 28.

[0029] In this configuration, to achieve a predetermined contact of the porous carburetor medium 30 against the carburetor medium contact surface 28 of the bottom wall 20, it may be assumed that, for example, in the basic state in which the porous carburetor medium 30 is not held against the bottom wall 20 by the holding projections 36, the porous carburetor medium 30 has a curved geometry that is more curved than the curvature of the carburetor medium contact surface 28. Then, during assembly, the porous carburetor medium 30 first contacts the bottom wall 20 with its central region, and then, due to the holding action of the holding elements 34, the radially outer region of the carburetor medium 30 is also pressed against the bottom wall 20. This ensures that, in particular, in the radially inner region, i.e., in the central region 22 of the combustion chamber bottom 16, where the liquid fuel is supplied, the porous carburetor medium 30 remains stably in contact with the carburetor medium contact surface 28 without the risk of an intermediate space being formed between the carburetor medium 30 and the bottom wall 20.

[0030] The concave curvature of the porous carburetor medium 30 ensures that the curve apex 38 of the porous carburetor medium 30, located in the central region 22 of the combustion chamber bottom 16, forms the region of the combustion chamber bottom 16 or the porous carburetor medium 30 that is set back the furthest relative to the combustion chamber 18 in the direction of the housing longitudinal axis L. In this case, the radially outer regions of the porous carburetor medium 30 are located further forward in the exhaust flow direction and, in particular, closer to the combustion air inlet openings 40 that are provided for introducing combustion air into the circumferential wall 12. As a result, there are no dead spaces, particularly in the radially outer regions, at the transition from the combustion chamber bottom 16 to the circumferential wall 12, where excessively high fuel concentrations could occur and the risk of deposits becoming particularly pronounced. Furthermore, the concavely curved geometry of the porous evaporator medium 30 results in such an installation of a vehicle heating device having a combustion chamber assembly 10 that the side 32 of the porous evaporator medium 30 facing the combustion chamber 18 is oriented vertically downward or obliquely downward, and the radially outer region of the porous evaporator medium 30 is located vertically further below the region of the curved apex 38, where the liquid fuel is also supplied into the porous evaporator medium 30. This means that gravity-assisted uniform distribution of the liquid fuel introduced into the porous evaporator medium 30 in the region of the curved apex 38 occurs radially outward. This, in conjunction with the increased surface area available for vaporization of the concavely curved porous evaporator medium 30 compared to the planar, non-curved structure of the porous evaporator medium, leads to a uniform and particularly efficient release of the vaporized fuel into the combustion chamber 18 throughout the porous evaporator medium 30.

[0031] 2 shows one variant of the combustion chamber assembly 10. In this configuration, a recess 42 is formed in the bottom wall 20 of the combustion chamber bottom 16. The recess 42 is open toward the combustion chamber 18 on a side 47 of the bottom wall 20 facing the combustion chamber 18, and a porous distributor medium 44 is accommodated in the recess 42. In this configuration, a first portion 46 of the vaporizer medium contact surface 28 is formed in the bottom wall 20, and a second portion 48 of the vaporizer medium contact surface 28 is surrounded by the first portion 46 of the vaporizer medium contact surface 28 and forms the porous distributor medium 44. In the case of this vaporizer medium contact surface 28 provided by two portions 46, 48, the vaporizer medium contact surface 28 has a concave curved structure with respect to the combustion chamber 18 on its side 26 facing the combustion chamber 18.

[0032] The porous distributor medium 44 is positioned in the central region 22 of the combustion chamber bottom 16, so that the liquid fuel supplied through the fuel supply conduit 24 first flows into the porous distributor medium 44 and is also dispersed radially outward within its volume. In this case, the liquid fuel is already uniformly dispersed in the radial direction or dispersed over a larger surface area, flows into the porous vaporizer medium 30 supported on the second portion 48 of the vaporizer medium contact surface 28, and is then further dispersed radially outward within its volume by capillary transport and, as mentioned above, also assisted by gravity. In order to achieve rapid and efficient radial pre-dispersion of the liquid fuel with the porous distributor medium 44, the distributor medium 44 preferably has a higher porosity than the porous vaporizer medium 30. This means that the porous distributor medium 44 first provides a very rapid and relatively coarse pre-dispersion, while the porous vaporizer medium 30, which is formed with a finer pore structure, then provides a very uniform distribution of the liquid fuel and therefore a very uniform release of the fuel towards the combustion chamber 18.

[0033] 2, the porous distributor medium 44 is curved throughout and has the same thickness D in substantially all circumferential and radial regions. This means that in such a configuration, liquid fuel dispersed radially outward in the porous distributor medium 44 flows through a greater area of ​​the porous distributor medium 44 from the radially inner to the radially outer side due to increasing distance relative to the housing longitudinal axis L.

[0034] To further improve the radially outward dispersion effect of the porous distributor medium, the thickness D of the porous distributor medium 44 can be increased from the radially inner side to the radially outer side, as shown in the embodiment shown in Figure 3, whereby the increasing thickness D, i.e., the increasing axial extension length, of the porous distributor medium 44 also contributes to increasing the fuel flow area provided for fuel dispersion in the radially outward direction of the porous distributor medium 44. To this end, as shown in Figure 3, the porous distributor medium 44, for example, on its side 50 opposite the combustion chamber 18 or vaporizer medium contact surface 28, can be oriented substantially perpendicular to the housing longitudinal axis L and thus can be formed substantially planar.

[0035] 4, a recess 54 is formed in the bottom wall 20 of the combustion chamber bottom 16 on the side 52 opposite the combustion chamber 18, and an insulating material 56 is contained in the recess 54. The insulating material 56 may be, for example, a foam material having a lower thermal conductivity than air, and particularly a lower thermal conductivity than the material of the bottom wall 20. The recess 54 may be closed by a cover 58, which stably holds the insulating material 56 in the recess 54. Thus, heat loss on the side 52 of the bottom wall 20 opposite the combustion chamber 18 is minimized in the volume area through which the relatively low-temperature combustion air supplied by the combustion air fan flows.

[0036] The illustrated configuration of the combustion chamber assembly, which includes a concavely curved structure of the porous carburetor medium, particularly on its side facing the combustion chamber, not only achieves the above-mentioned aspects of efficient radially outward distribution of fuel and avoidance of dead spaces, but also increases the radially inward distance from the side of the porous carburetor medium facing the combustion chamber to the ignition mechanism, e.g., a glow plug, which generally extends radially inward from the circumferential wall with only a very small axial distance from the bottom of the combustion chamber. This avoids the risk of localized overheating of the porous carburetor medium in the curved structure. This also reduces the risk of thermal breakdown of the porous carburetor medium over its operating life.

Claims

1. A combustion chamber assembly for a vaporizer burner, comprising a combustion chamber housing (14) having a peripheral wall (12) extending in the direction of a housing longitudinal axis (L) and defining a combustion chamber (18) radially outward, and a combustion chamber bottom (16) defining the combustion chamber (18) in the axial direction, the combustion chamber bottom (16) having a vaporizer bottom (16) on its side (26) facing the combustion chamber (18) that is concavely curved relative to the combustion chamber (18). A combustion chamber assembly including a bottom wall (20) having a vaporizer medium contact surface (28) and providing at least a portion of the vaporizer medium contact surface (28), wherein a porous vaporizer medium (30) is provided on a side (26) of the combustion chamber bottom (16) facing the combustion chamber (18), and the porous vaporizer medium (30) is concavely curved with respect to the combustion chamber (18) on its side (32) facing the combustion chamber (18), In order to fix the porous evaporator medium (30) on its outer peripheral surface to the combustion chamber bottom (16), the combustion chamber bottom (16) has a retaining element (34) annularly surrounding the bottom wall (20), the retaining element (34) having at least one retaining protrusion (36) that holds the porous evaporator medium (30) on its side (32) facing the combustion chamber (18) to the bottom wall (20), and the porous evaporator medium (30) has a curved geometric shape with a curvature stronger than the curvature of the evaporator medium contact surface (28) in a basic state when it is not held to the bottom wall (20) by the at least one retaining protrusion (36).

2. 2. The combustion chamber assembly of claim 1, wherein the porous evaporator medium (30) is concavely curved relative to the combustion chamber (18) and / or the porous evaporator medium (30) has a substantially constant thickness (d).

3. 2. The combustion chamber assembly according to claim 1, wherein in a radially central region (22), a fuel supply conduit (24) opens into the combustion chamber bottom (16), and the porous carburetor medium (30) has a curved apex (38) in the radially central region (22).

4. 2. The combustion chamber assembly according to claim 1, wherein the curved geometry of the evaporator medium contact surface (28) substantially corresponds to the curved geometry of the porous evaporator medium (30) on the side (32) facing the combustion chamber (18).

5. The combustion chamber assembly of claim 1 , wherein the bottom wall (20) provides substantially the entire carburetor medium contact surface (28).

6. 2. The combustion chamber assembly of claim 1, wherein the bottom wall (20) has a recess (32) that is open toward a side (47) of the bottom wall facing the combustion chamber (18) for accommodating a porous distributor medium (44), and wherein a first portion (46) of the vaporizer medium abutment surface (28) is provided on the bottom wall (20) and a second portion (48) of the vaporizer medium abutment surface (28) is provided on the porous distributor medium (44).

7. 7. The combustion chamber assembly of claim 6, wherein the first portion (46) of the evaporator medium contact surface (28) annularly surrounds the second portion (48) of the evaporator medium contact surface (28), and / or the porous distributor medium (44) is disposed substantially centered with respect to the housing longitudinal axis (L), and / or the porous distributor medium (44) has a higher porosity than the porous evaporator medium (30).

8. 7. The combustion chamber configuration according to claim 6, wherein the porous distributor medium (44) is curved on a side (50) opposite the vaporizer medium contact surface (28), and the curved geometry of the porous distributor medium (44) on the side (50) opposite the vaporizer medium contact surface (28) substantially corresponds to the curved geometry of the porous distributor medium (44) in the second portion (48) of the vaporizer medium contact surface (28), or / and the porous distributor medium (44) has a substantially constant thickness (D).

9. 7. The combustion chamber configuration according to claim 6, wherein the porous distributor medium (44) extends substantially perpendicular to the housing longitudinal axis (L) on its side (50) opposite the evaporator medium contact surface (28), and / or the porous distributor medium (44) has a thickness (D) that increases from the radially inner side to the radially outer side.

10. 2. The combustion chamber assembly according to claim 1, wherein an insulating material (56) is arranged on the side (52) of the bottom wall (20) opposite the evaporator medium contact surface (28).

11. 11. A fuel-operated vehicle heating system having a burner region with a combustion chamber assembly (10) according to any one of claims 1 to 10.

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