Combustion chamber wall and combustion chamber assembly for a heating device in a vehicle and method for producing same

Abstract

A combustion chamber wall for a combustion chamber assembly (100) of a heating device (1) in a vehicle is configured to form a combustion chamber (8). It comprises a cylindrical circumferential wall (44) which defines a central axis (C) extending in the axial direction (X). At least one structure (22) for introducing an oxidizer into the combustion chamber (8) is formed in the circumferential wall (44). The structure comprises a relief (52) formed in the circumferential wall, which forms an inlet opening, and a formed section (54) formed in the circumferential wall (44), which is shaped in a radial direction (R) towards the central axis (C). The relief (52) adjoins the formed section (52) shaped towards the central axis (C) directly in a circumferential direction (P) of the circumferential wall (44).

Description

Technical area:

[0001] The present invention relates to a combustion chamber wall and a combustion chamber assembly comprising the same for a heating device in a vehicle, in particular for a heating device with an evaporator burner, the corresponding heating device and a method for producing the combustion chamber assembly. Technical background:

[0002] Known heating devices based on combustion technology, such as those used particularly in vehicles, including mobile air or water heaters, typically comprise a combustion chamber assembly including a combustion chamber housing. A combustion chamber housing defines a combustion chamber into which a fuel is introduced, for example, by directly injecting a fuel into the combustion chamber, by supplying a fuel-air mixture prepared outside the combustion chamber, or by supplying and subsequently vaporizing the fuel in a porous evaporator, which may be heated for the purpose of vaporization, etc. Furthermore, an ignition element, which initiates and optionally maintains the combustion process, may be located in the combustion chamber.In particular in the case of a separate supply of fuel and oxygen-containing gas, in particular air, corresponding inlet openings can also be provided in a peripheral or bottom wall of the combustion chamber.

[0003] To achieve efficient and, above all, low-emission combustion in the combustion chamber, it is desirable to achieve good mixing of gaseous fuel and atmospheric oxygen. The fuel can be fed into the mixing zone in gaseous form or in the form of an aerosol. This is often caused by swirling the air flowing into the combustion chamber. Measures for this can include air guide elements arranged in the combustion chamber, which can be located near the inlet openings, but these significantly increase costs and manufacturing effort. Swirl can also be created by other design measures, for example axial / tangential swirlers. Such swirlers are individual, sometimes complex, components that are arranged upstream of the combustion chamber, are integrated into the combustion chamber, or are part of the combustion chamber. This complexity therefore significantly increases costs and effort.

[0004] An alternative approach involves generating the swirl using tangentially positioned holes through a circumferential wall of the combustion chamber. However, this requires a minimum thickness of the circumferential wall of approximately the diameter of the hole, which in practice can potentially lead to greater material expenditure and unwanted weight gain. Tangentially positioned holes therefore cannot be directly inserted into a thin-walled combustion chamber; in this case, a separate thick-walled part must usually be created and implemented in the heater.

[0005] Another possibility for generating a swirl in the air-fuel mixture in the combustion chamber can be achieved by means of tabs pressed into the peripheral wall, e.g. by reshaping the wall material. flaps). This allows the installation of swirl-generating inlet openings even in thin peripheral walls. In addition to such flaps, completely normal radially inward-facing holes (air inlet openings) can also be provided.

[0006] Such a proposal for tab-like, indented air inlet openings is known for the specific case of a combustion chamber assembly for an evaporator burner. The air inlet openings are formed in the region of respective gill-like protrusions on the peripheral wall. An air guide surface formed by radially inward forming guides the air flowing in via an air supply chamber or a corresponding duct with a tangential flow direction into the combustion chamber. In particular, the air inlet openings each have an opening surface normal that is orthogonal to a radial line relative to a longitudinal axis of the combustion chamber. In other words, the opening surface itself is perpendicular to the peripheral wall in order to achieve the tangential introduction of the air into the combustion chamber.

[0007] However, this approach also has disadvantages. Firstly, to offer an economically viable solution for the formation of such tabs, a spinning tool and a counter-stop are usually used. This requires the circumferential wall of the combustion chamber to be split along a line. As internal tests have shown, such a split using a spinning tool does not correspond to a proper cutting process, but rather to a tearing of the material along this line.

[0008] When the tool is new, this separation takes place with satisfactory results in terms of the quality of the parting line or the two resulting edge sections that are drawn apart in the radial direction. However, with progressive tool wear, burrs increasingly form that are aligned in such a way that they reduce the flow cross-section and thus significantly and adversely affect the conditions under which combustion takes place. To prevent this loss of quality, every peripheral wall or every manufactured combustion chamber assembly that has this peripheral wall should be inspected for burrs after the production process. This could, for example,using a pressure loss test bench, which, however, significantly increases the production costs and the production time, not to mention that the tools in question may no longer be usable at an early stage of their actual useful life.

[0009] As internal tests have also shown, a further disadvantage of the approach described above is that the tangentially oriented opening area of ​​the inlet opening initially causes the introduced air to flow directly along the peripheral wall. However, due to the Coandæ effect, this flow then remains on the peripheral wall in a radially outer region of the combustion chamber for a longer period of time. The desired swirl is therefore only generated in the radially outer region of the combustion chamber and decreases sharply towards its longitudinal or central axis. As a result, sufficient mixing in the combustion chamber only occurs to a limited extent. For this purpose, the aim is rather to generate the swirl as homogeneously as possible across the radial direction. Presentation of aspects of the invention

[0010] It is therefore an object to improve the swirl introduction into a combustion chamber of a combustion chamber assembly, in particular to improve the mixing of a fuel with a corresponding oxidizer such as the oxygen in the air, and at the same time to limit costs and effort in production.

[0011] One aspect of the invention relates to a combustion chamber wall for a combustion chamber assembly or for a heating device in a vehicle, comprising a cylindrical peripheral wall defining a central axis extending in the axial direction and forming a combustion chamber. At least one structure for introducing an oxidizer into the combustion chamber is formed in the peripheral wall. This structure comprises a free cut formed in the peripheral wall, which forms an inlet opening, and a formed section formed in the peripheral wall, which is shaped in a radial direction toward the central axis. In a circumferential direction of the peripheral wall, the free cut directly adjoins the formed section shaped toward the central axis.

[0012] The vehicle may be a motor vehicle, a trailer or caravan, a mobile home, a construction machine or even an aircraft or watercraft, etc., and the term vehicle is to be interpreted broadly.

[0013] The proposed combustion chamber wall with the structure for introducing an oxidizer into the combustion chamber offers advantages in terms of both manufacturing technology and fluid mechanics. In particular, the inclusion of the free cut leads to a surprising synergistic effect: the free cut can, for example, be made in the material of the peripheral wall in a first process step of the corresponding manufacturing process. The free cut means that a flat section of material is removed from the material of the peripheral wall, resulting in the formation of a hole. This process can advantageously be a punching process. In this process, the material is separated by shearing. Burr formation is negligible in this process.

[0014] This process can also be performed in conjunction with perforation of the combustion chamber, creating a plurality of smaller (radially directed) inlet openings for introducing the oxidizer. Punching the cutout therefore represents hardly any additional effort. However, alternative laser cutting or another easily automated method for forming the cutout is also possible. Here, too, burr formation may be negligible or not occur as expected.

[0015] Once the relief cut has been formed, the forming section in the peripheral wall can be produced. The forming process can be applied locally to a section of the peripheral wall material, which includes at least one ("second") edge section of the relief cut, which faces the circumferential direction of the peripheral wall in the assembled state. Thus, the conventional "tearing" of the wall material to form the inlet opening is eliminated during the radial forming process toward the center axis. This also eliminates the formation of burrs. The opening area of ​​the inlet opening can now be precisely and burr-freely adjusted during production.

[0016] The free cut can thus be manufactured particularly economically and reliably. The risk of burrs extending into the flow area of ​​the inlet opening is completely eliminated. This also eliminates the need for a subsequent inspection process. Furthermore, it is possible to use a thin-walled material to create a tangentially directed swirl, which reduces costs, effort, and weight.

[0017] The aforementioned synergy effect is achieved by the associated further advantage of improving the flow characteristics of the oxidizer introduced into the combustion chamber. The geometry of the inlet opening formed by the free cut and the forming section is determined by the dimensions of the free cut, in particular its circumferential length, and by a drawing depth of the forming section pointing toward the center axis. First and second edge sections of the free cut, which are opposite one another in the circumferential direction, can thus be spaced apart in the circumferential direction by the free cut itself and also in the radial direction by the forming section.

[0018] The inflow angle and the flow area can therefore be adjusted via the drawing depth at one (second) edge section of the free cut - according to exemplary embodiments also at both edge sections. The same applies to the selected length of the free cut in the circumferential direction. According to exemplary embodiments, this design can therefore generate not only a tangential velocity component but also a radial velocity component. The free cut makes a purely tangential adjustment of the passage area impossible - in plan view (from the outside along the radial direction), it would then have a vanishingly small length in the circumferential direction, i.e., it would be non-existent, which would correspond to the prior art described above.

[0019] However, due to the additional radial component of the flow—in addition to the tangential component—the Coanda effect no longer occurs, as the flow is not confined to the combustion chamber wall. Instead, a homogeneous swirl flow is generated across the entire combustion chamber cross-section, achieving good mixing.

[0020] As described, the free cut forming the inlet opening directly adjoins the formed section shaped towards the center axis in a circumferential direction of the circumferential wall. The free cut can be defined by its edge sections lying opposite one another in the circumferential direction (as well as end sections lying in the axial direction). Due to the radially inward deformation of the formed section, which includes the second edge section, towards the center axis, the free cut is over-shaped, but remains a free cut. The direct adjoining therefore refers to the fact that the second edge section of the free cut is part of the formed section and this edge section faces the circumferential direction of the circumferential wall, so that the inlet opening formed by the free cut extends in the circumferential direction from the radially indented formed section.This expressly does not preclude the forming section from encompassing the free cut, as is provided in a specific embodiment described below. Here, the inlet opening is located on one flank of the forming section in the circumferential direction, but the free cut still adjoins the forming section in the circumferential direction through its second edge portion on this flank.

[0021] The oxidizer usable with the combustion chamber wall or the combustion chamber assembly can be air, or pure oxygen, or another oxygen compound suitable for oxidizing the fuel. The fuel can be diesel or gasoline. Kerosene, hydrogen, or other propellants are also possible. The aspects of the invention are not limited to specific substances with regard to fuel and oxidizer.

[0022] The peripheral wall is cylindrical. The peripheral wall can be a section of a wall component that has multiple sections, e.g., a flange, a section tapering conically toward the flame tube, and / or the flame tube itself, etc.

[0023] In the combustion chamber assembly, a base section and the wall component can be firmly connected to one another, e.g., welded. The base section can comprise an evaporator receptacle and, e.g., a porous evaporator, to which the fuel is supplied in a known manner for evaporation. An electric heating device, e.g., can assist the evaporation process. Alternatively, the fuel can also be injected via a nozzle arranged in the base section. Furthermore, the base section can instead have a supply line for a prepared fuel-oxidizer mixture. The invention is not limited to specific designs of the base section, and further embodiments are possible.

[0024] The combustion chamber assembly formed by the combustion chamber wall may further comprise an ignition element arranged at least partially within the combustion chamber, with which a combustion process can be started and / or maintained. Flame baffles may also optionally be installed in the combustion chamber.

[0025] It should be noted that the invention fundamentally encompasses an embodiment of a combustion chamber assembly in which a forming process takes place first during production, followed by the removal of material to form the free cut. The burrs created at the tear edge during the forming process are removed during the subsequent punching or cutting with the tear edge (assuming the drawing die still provides this structure), leaving only the corresponding second edge section of the free cut.

[0026] Advantageous developments and embodiments are described below, some of which are also reflected in the appended dependent claims. Some of these have already been outlined above.

[0027] For example, the clearance can be defined by the first and second edge sections already indicated above, which are opposite one another and spaced apart in the circumferential direction. The second edge section is part of the section of the circumferential wall shaped toward the center axis. In this case, the first edge section can be at a greater distance from the center axis than the second edge section. This creates a swirl flow with a radially inward-directed component, which results in improved mixing and avoids the Coanda effect.

[0028] A further embodiment provides that the inlet opening forms an opening surface with a surface normal that corresponds to a flow vector of the oxidizer passing through the inlet opening, wherein the surface normal has a radial component in the radial direction and a tangential component in the circumferential direction with respect to the center axis of the circumferential wall in order to generate a swirl in the combustion chamber in the case of an oxidizer flow introduced through the inlet opening.

[0029] A special refinement of the combustion chamber wall provides for at least two, preferably four or more, structures for introducing an oxidizer into the combustion chamber to be arranged in the peripheral wall. A larger number of structures for introducing an oxidizer into the combustion chamber allows for improved fine-tuning of the mixing homogeneity due to the radial flow component and prevents vibrations / frequencies during the combustion process. It is advantageous to distribute several flaps (more than two) around the circumference, which progressively reduces secondary vortices and reduces their influence on combustion.

[0030] According to one embodiment, the structures for introducing an oxidizer into the combustion chamber are arranged in the peripheral wall at an equal distance from the base section to be mounted on the front side or a surface of an evaporator arranged therein. This arrangement creates a homogeneous swirl and thus a homogeneous mixing of the introduced oxidizer with the fuel-gas mixture in the combustion chamber.

[0031] According to another embodiment, the structures for introducing an oxidizer into the combustion chamber can be arranged in the circumferential wall in succession at equal distances from one another. The effect is similar to that described with reference to the previous embodiment.

[0032] According to embodiments, the peripheral wall of the combustion chamber wall can be formed from a metal, preferably a steel sheet comprising a steel alloy. In this case, the formed section of the peripheral wall can be formed by deep drawing in the radial direction toward the center axis. The advantages have already been explained above.

[0033] Furthermore, the cutout can be formed by punching or cutting out, and removing a first section from the peripheral wall. This has also been indicated above.

[0034] In the combustion chamber assembly, according to embodiments, the combustion chamber can be connected via the inlet opening to an oxidizer supply chamber or an oxidizer supply channel surrounding the peripheral wall.

[0035] According to exemplary embodiments, the forming section can have a convexly curved shape that breaks off in the circumferential direction with the second edge portion toward the free cut. The forming section thus takes the form of a depressed tab, but with, among other things, a circumferentially offset or forwardly positioned free cut.

[0036] According to a further embodiment, the forming section of the combustion chamber wall can be designed substantially symmetrically with respect to an axis extending in the tangential or circumferential direction. Minor deviations from the symmetry that do not affect the flow direction of the oxidizer passing through the inlet opening are irrelevant. The forming section of this embodiment has a first length along this axis up to the second edge section, which is greater than a second length of the free cut between the first edge cut and the second edge section along this axis. This avoids an excessively strong radial component of the flow, which could impair the swirl.

[0037] According to a further embodiment, the forming section of the combustion chamber wall can have a drawing depth with respect to the radial direction, caused by a forming process, which—optionally in conjunction with a relatively small thickness of the material of the forming section—results in a radially outward-facing surface of the forming section adjacent to the second edge section being positioned closer to the center axis by a distance difference than a radially inward-facing surface of the surrounding wall adjacent to the first edge section. This measure allows the radial component of the flow direction through the inlet opening to be adjusted.

[0038] The distance difference can optionally be less than a second length of the clearance between the first edge cut and the second edge section along an axis extending in a tangential direction. This avoids an overly dominant tangential flow component, which could lead to the Coanda effect.

[0039] According to a special embodiment already mentioned above, in addition to the actual forming section, a region of the circumferential wall adjacent to the first edge section can also be formed in the radial direction towards the center axis. In principle, the forming section can therefore extend around the free cut with its flank pointing in the circumferential direction. A condition that the second edge section has a smaller distance from the center axis of the circumferential wall than the first edge section is preferably maintained in order to generate the radial component of the flow direction of the oxidizer flowing through the inlet opening. A particular advantage of this embodiment arises from the fact that the inlet opening itself, with its radially outermost first edge section, is raised (i.e. offset from the center axis) in the inward-facing surface of the circumferential wall.The flow enters the combustion chamber through the inlet opening at a distance from this combustion chamber wall and the Coanda effect is thereby further suppressed.

[0040] Aspects of the invention also relate to a combustion chamber assembly comprising the combustion chamber wall according to one of the above aspects or embodiments, further comprising a bottom portion, wherein the bottom portion and the cylindrical peripheral wall form a combustion chamber housing and define the combustion chamber therein, and wherein the bottom portion is configured to supply a fuel to the combustion chamber.

[0041] Aspects of the invention also relate to a heating device comprising the described combustion chamber assembly with the combustion chamber wall. The heating device can provide a heat exchanger and corresponding supply and discharge lines for the medium to be heated (cooling medium). This can be, for example, air or water. The heating device can, in particular, be an air heater. air heater ). In this case, the heating device may additionally comprise a hot air fan with a motor, corresponding control device, and electrical power source.

[0042] Aspects of the invention also relate to a method for producing the combustion chamber wall, comprising: Providing a material for the peripheral wall; punching or cutting out a first section from the material of the peripheral wall to form the free cut; then forming, preferably deep drawing, a second section in the material of the peripheral wall to form the formed section, wherein the free cut directly adjoins the formed section.

[0043] The advantages are the same as described above. Short description of the drawings:

[0044] The invention described above will now be explained by way of example with reference to the accompanying drawings using a preferred embodiment.

[0045] They show: Figure 1 shows a schematic sketch of a cross-section of a heating device based on combustion technology according to an embodiment; Figure 2 shows a side view of a peripheral wall component of the heating device made of Fig. 1 ; Figure 3 as Fig. 2 , but in perspective view; Figure 4 a cross-sectional view of the peripheral wall component from Fig. 2 along its center axis in the direction of the flange end; Figure 5 as Fig. 4 , but towards the flame tube end; Figure 6 in plan view and enlarged one of the Fig. 1 - 5 shown structures for introducing an oxidizer into the combustion chamber; Figure 7 as Fig. 6 , but in cross-sectional view along the line AA; Figure 8 the same plan view as in Fig. 6 , but with illustrated lengths and widths of free cut and forming section; Figure 9 the same plan view as in Fig. 7 , but with illustration of the surface normal of the opening plane or the flow direction with directional components; Figure 10 Top view as in Figure 6 , but for modified embodiment; Figure 11 Cross-sectional view as in Fig. 7 , but for the modified embodiment from Fig. 10 , along line BB. Detailed description of preferred embodiments:

[0046] In the following description of preferred embodiments, it should be noted that the present disclosure of the various aspects is not limited to the details of the construction and arrangement of the components as shown in the following description and in the figures. All embodiments, even those not shown in the figures, can be practiced or carried out in various ways. It should also be noted that the phraseology and terminology used herein is used for the purpose of specific description only and should not be construed as such by one skilled in the art.Furthermore, in the following description, the same reference numerals in the figures denote the same or similar features or objects, so that in some cases a repeated detailed description of the same is omitted in order to maintain the compactness and clarity of the illustration.

[0047] In the Fig. 1A schematic sketch shows a cross-section of a heating device 1 based on combustion technology according to an exemplary embodiment. The heating device 1 comprises a combustion chamber assembly 100 and a heat exchanger 200. The combustion chamber assembly 100 comprises a combustion chamber 8, an evaporator receptacle 10, and an evaporator element 12 for evaporating a liquid fuel. The combustion chamber 8, the evaporator receptacle 10, and the evaporator element 12 are designed to be essentially rotationally symmetrical. The combustion chamber 8 is delimited in the circumferential direction by a surrounding circumferential wall component 14, in particular by a thin-walled circumferential wall 44 (cf. Fig. 2), which represents a cylindrical section of the peripheral wall component 14 and has a cylindrical, longitudinal, or central axis C. The combustion chamber 8 is bounded at its front end by the evaporator receptacle 10 in the area of ​​the fuel supply, which comprises a fuel supply pipe 36. The evaporator element 12 is accommodated in the evaporator receptacle 10 on the side facing the combustion chamber 8.

[0048] The combustion chamber assembly 100 also includes, on the side of the evaporator receptacle 10 facing away from the combustion chamber 8, a cap-like guide element for supplying the oxidizer, e.g., combustion air. The guide element 16 is placed over the evaporator receptacle 10. An oxidizer supply chamber 20 is formed annularly around the combustion chamber 8. A gap 18 between the evaporator receptacle 10 and the guide element 16 opens into the oxidizer supply chamber 20. From the oxidizer supply chamber 20, a fluid connection is established with the combustion chamber 8 via inlet openings of structures 22 for introducing an oxidizer into the combustion chamber, which are formed in the thin-walled peripheral wall 44 of the peripheral wall component 14. The structures 22 are described in more detail below. The peripheral wall with structures incorporated therein represents an embodiment of a combustion chamber wall according to the invention.

[0049] The fuel supply line 36 is arranged within an oxidizer supply line 24, which conducts the oxidizer to the gap 18, so that during use the oxidizer flows around it and is thereby cooled. A first flow path 142 for the exhaust gases is formed in the heat exchanger 200. The exhaust gases flow within the heat exchanger 200 along the first flow path 142 to an exhaust gas discharge line 144, via which the exhaust gases are conducted to the outside. Furthermore, a second flow path 146 is provided within the heat exchanger 200, through which the cooling fluid of the motor vehicle, e.g., air, is conducted. The first 142 and the second 146 flow paths are arranged such that, during use, heat is effectively transferred from the exhaust gases to the cooling fluid.

[0050] The Fig. 1 The peripheral wall component 14 shown is shown in greater detail in the Fig. 2 to 5 shown. The Figures 2 and 3show the peripheral wall component 14 in side and perspective view, while the Figures 4 and 5 Views along the center axis C in the direction of the flange-side end and the flame tube-side end, respectively. The peripheral wall component 14 essentially comprises four sections, namely a flange 40, with which the peripheral wall component 14 can be connected to the base section 26, the essentially cylindrical peripheral wall 44, a chronically tapered section 46, and a flame tube section 48.

[0051] The thin-walled peripheral wall component 14 is made in one piece and is preferably made of a stainless steel alloy with a wall thickness d of 1 mm (cf. Fig. 7). For example, the inner diameter of the peripheral wall 44 defining the combustion chamber 8 may be 45 mm in the case of an air heater with an output of 1-5 kW. In the case of an air passage with an output of 5-15 kW, the inner diameter may be 70 mm.

[0052] Where - as in Fig. 1 can be seen - the oxidizer supply chamber 20 extends as a pre-chamber around the peripheral wall 44 (ring-shaped), the structures 22 for supplying the oxidizer into the combustion chamber 8 and a plurality of smaller, radially directed inlet openings 42 are formed in the peripheral wall 44.

[0053] The structures 22 are arranged circumferentially at equal distances from one another in the circumferential direction P and at the same distance in the axial direction X from the flange 40 or the base section 26. In the Figures 4 and 5It can be seen that four of the structures 22 are formed. The structures 22 comprise a free cut 52 and a forming section 54. The free cut 52 is arranged behind the forming section 54 in the circumferential direction P and is directly adjacent to it. The free cut 52 and the forming section 54 are formed contiguously. The free cut 52 forms a larger inlet opening than the radially directed inlet openings 42. The oxidizer supply chamber 20 is in fluid communication with the combustion chamber 8 via the inlet openings 42 and the respective free cuts 52 as inlet openings of the structures 22.

[0054] In the Figures 2 - 5Also shown in particular is the cylindrical coordinate system used here for description with the axial direction X, the radial direction R and the circumferential direction P. The circumferential wall 44 also has a radially inwardly facing surface 441 and a radially outwardly facing surface 442. In the circumferential wall, a tangential direction T is also defined locally, see Fig. 5 .

[0055] The Figs. 6 and 7 show in top view ( Fig. 6 ) from the outside or in cross-sectional view ( Fig. 7 ) the structures 22 for introducing an oxidizer into the combustion chamber 8 in greater detail.

[0056] As described, the structure 22 comprises a forming section 54 and a free cut 52. In Figure 6the circumferential direction P is oriented parallel to the line AA to the left. The free cut 52 is directly adjacent to the forming section 54 in the circumferential direction P. The free cut 52 has a direction in the axial direction X (direction from bottom to top in Figure 6 ) has an elongated shape with two edge sections 60, 62 opposite one another in the circumferential direction P. The first edge section 60 is formed in the flat, non-formed circumferential wall 44 and faces the forming section 54, while the second edge section 62 points in the circumferential direction P. In the exemplary embodiment, the edge sections 60, 62 are formed parallel to one another. The free cut 52 is formed by removing material from the circumferential wall 44, e.g., in a punching process together with the formation of the inlet openings 42, or by laser cutting, etc.

[0057] The forming section 54 is - as is the free cut 52 - mirror-symmetrical to an axis directed in the tangential direction T (corresponds to the line AA in Fig. 6 ). The forming section 54 is formed in the radial direction R towards the center axis C, in particular by a deep drawing process with a drawing depth z, see Fig. 7 The deep-drawing mold used for this process creates a convex shape for the forming section 54 that is curved radially towards the center axis C, which thus takes on the shape of a tab because the forming section 54 breaks off in the circumferential direction P at the second edge section 62 towards the free cut 52. As shown in Figure 7 As can be seen, the first edge portion 60 is located opposite the second edge portion 62 in the circumferential direction P. However, due to the drawing depth z, the second edge portion 62 is positioned closer to the center axis C in the radial direction R than the first edge portion 60.

[0058] In particular, an outwardly facing surface 443 adjacent to the second edge portion 62 and the inwardly facing surface 441 of the peripheral wall 44 adjacent to the first edge portion 60 form a distance difference s with respect to their distance from the center axis C, which in the exemplary embodiment is 0.5 mm. The drawing depth z in the exemplary embodiment is 1.5 mm, and the wall thickness d is 1 mm.

[0059] By this choice of sizes, an inclined opening surface plane O is created for the inlet opening formed by the cutout 52, as shown in the Fig. 7 analog Fig. 9The surface normal N, which ideally corresponds to the flow direction of the oxidizer flowing through the inlet openings, therefore has a tangential component NT and a radial component NR. The tangential component NT thus generates a swirl in the combustion chamber 8, while the radial component NR prevents the Coanda effect and distributes the flow strength homogeneously in the radial profile, thus improving mixing.

[0060] In Figure 8 are in the Figure 6 An analogous top view of the structure 22 shows the length and width ratios for the free cut 52 and the forming section 54. Here, a length is viewed in the circumferential direction P, and a width in the axial direction X. In this view, the free cut 52 is almost twice as wide as it is long. The width w1 is 5.4 mm, and the length l1 is 2 mm.

[0061] The width w2 of the forming section 54 is also 5.4 mm or slightly more in the special embodiment, which does not limit the generality of the inventive concept, since it runs out laterally in the axial direction X, as can be seen in Figure 8. The length l2 of the forming section 54 along the axis (line AA in Fig. 6 ) in the circumferential direction is also 5.4 mm up to the second edge section 62. On both sides in the axial direction X, the forming section 54 also encompasses the free cut 52, as the Fig. 6 and 8 The forming section 54 is thus longer than the free cut 52, while the widths w1, w2 are approximately comparable.

[0062] The specifications refer to a 1-5 kW air heater with an inner diameter of the peripheral wall of 45 mm. For a 5-15 kW air heater with an inner diameter of 70 mm, the dimensions are approximately twice as large.

[0063] The dimensions specified above can be selected differently individually or altogether in modified embodiments.

[0064] A further modified embodiment is shown in the Figures 10 and 11 shown. The forming section 54 is supplemented here by an extended forming section 56, with which the free cut 52 is encompassed by the forming of the peripheral wall 44 inwards towards the center axis C. As in Figure 11 As can be seen, the first edge section 60 is also formed in the radial direction R toward the central axis C. Overall, this measure displaces the cutout 52 or the inlet opening of the structure 22 formed thereby toward the central axis, so that it is raised above the surrounding, inward-facing surface 441 of the peripheral wall 44. This also prevents the Coanda effect.

[0065] The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the realization of the invention both individually and in any combination. List of reference symbols

[0066] 1 Heating device 8 Combustion chamber 10 Evaporator holder 12 Evaporator element 14 Circumferential wall for combustion chamber 16 Oxidizer guide element 18 Gap 20 Oxidizer supply chamber 22 Structure for introducing an oxidizer into the combustion chamber 24 Oxidizer supply line 26 Bottom section 30 Side wall of the bottom section 32 Ignition element 36 Fuel supply line 40 Flange 42 Radially directed, smaller inlet openings 44 Circumferential wall 46 Conical section 48 Flame tube section 52 Free cut 54 Forming section 56 Extension of the forming section 60 First edge section 62 Second edge cut 100 Combustion chamber assembly 142 First flow path 144 Exhaust gas discharge line 146 Second flow path 200Heat exchanger 441Inward-facing surface of the peripheral wall 442Outward-facing surface of the peripheral wall CCenter axis, cylinder axis, longitudinal axis of the peripheral wall XAxial direction RRadial direction PCircumferential direction TTangential direction (in structure 22) dWall thickness sDistance difference zDrawing depth

Claims

1. A combustion chamber wall for a combustion chamber assembly (100) of a heating device (1) in a vehicle, the combustion chamber wall being configured to form a combustion chamber (8), comprising: a cylindrical peripheral wall (44) defining a central axis (C) extending in the axial direction (X); at least one structure (22) for introducing an oxidizer into the combustion chamber (8) being formed in the peripheral wall (44), the structure comprising: - a free cut (52) formed in the peripheral wall, which forms an inlet opening; and - a forming section (54) formed in the peripheral wall (44), which is shaped in a radial direction (R) toward the central axis (C); - the free cut (52) directly adjoins the forming section (52) shaped toward the central axis (C) in a circumferential direction (P) of the peripheral wall (44).

2. Combustion chamber wall according to claim 1, wherein the cutout (52) is defined by first and second edge portions (60, 62) opposite one another and spaced apart from one another in the circumferential direction (P); the second edge portion (62) is part of the forming portion (54) of the circumferential wall (44) shaped toward the center axis (C); and the first edge portion (60) is at a greater distance from the center axis than the second edge portion (62).

3. Combustion chamber wall according to claim 1 or 2, wherein the inlet opening forms an opening area (O) with a surface normal (N) which corresponds to a flow vector of the oxidizer passing through the inlet opening; and the surface normal (N) has a radial component (N R ) and in the circumferential direction (P) a tangential component (N T) in order to generate a swirl in the combustion chamber (8) in the event of an oxidizer flow introduced through the inlet opening.

4. Combustion chamber wall according to one of claims 1 to 3, wherein at least two, preferably four of the structures (22) for introducing an oxidizer into the combustion chamber (8) are arranged in the peripheral wall (44).

5. Combustion chamber wall according to claim 4, wherein the structures (22) for introducing an oxidizer into the combustion chamber (8): - are arranged in the peripheral wall (44) at an equal distance from a base portion (26) to be connected to the peripheral wall at the end face or a surface of an evaporator arranged therein; and / or - are arranged in the peripheral wall (44) successively in the circumferential direction (P) at equal distances from one another.

6. Combustion chamber wall according to one of claims 1 to 5, wherein the peripheral wall (44) is formed from a metal, preferably a steel sheet comprising a steel alloy; and the forming section (54) of the peripheral wall (44) is formed by deep drawing in the radial direction (R) toward the center axis (C).

7. Combustion chamber wall according to one of claims 1 to 6, wherein the cutout (52) is formed by punching or cutting out and removing a first portion from the peripheral wall (44).

8. Combustion chamber wall according to one of claims 1 to 7, wherein the combustion chamber (8) is connected via the inlet opening to an oxidizer supply chamber (20) surrounding the peripheral wall (44) or to an oxidizer supply channel.

9. Combustion chamber wall according to one of claims 1 to 8, wherein the forming section (54) has a convexly curved shape which breaks off in the circumferential direction (P) with the second edge section (62).

10. Combustion chamber wall according to one of claims 1 to 9, wherein the forming section (54) is formed substantially symmetrically with respect to an axis (AA, BB) extending in the tangential direction (T) and has a first length (l2) along this axis up to the second edge section (62) which is greater than a second length (l1) of the free cut (52) between the first edge cut (60) and the second edge section (62) along this axis.

11. Combustion chamber wall according to one of claims 1 to 10, wherein the forming section (54) has a drawing depth (z) caused by a forming process with respect to the radial direction (R), which results in a radially outwardly facing surface (443) of the forming section adjacent to the second edge section (62) being positioned closer to the center axis (C) by a distance difference (s) than a radially inwardly facing surface (441) of the peripheral wall (44) adjacent to the first edge section (60).

12. Combustion chamber wall according to claim 11, wherein the distance difference (s) is less than a second length (i1) of the free cut between the first edge section (60) and the second edge section (62) along an axis (AA, BB) extending in the tangential direction (T).

13. Combustion chamber wall according to one of claims 1 to 12, wherein, in addition, a region of the peripheral wall (44) adjacent to the first edge portion (60) is shaped in the radial direction (R) toward the center axis (C); and / or a plurality of radially directed inlet openings (42) for introducing the oxidizer, which are smaller in size than the free cut, are formed in the peripheral wall (44).

14. Combustion chamber assembly (100) comprising the combustion chamber wall according to one of claims 1 to 13, further comprising a bottom portion (26), wherein the bottom portion (26) and the cylindrical peripheral wall (44) form a combustion chamber housing and define the combustion chamber (8) therein, and wherein the bottom portion (26) is configured to supply a fuel to the combustion chamber (8).

15. Heating device (1) for a vehicle, comprising the combustion chamber assembly (100) according to claim 14.

16. A method for producing a combustion chamber wall according to one of claims 1 to 13, comprising: - providing a peripheral wall; - punching or cutting out a first section from the material of the peripheral wall to form the free cut; - forming, preferably deep drawing, a second section in the material of the peripheral wall to form the formed section, wherein the free cut directly adjoins the formed section.

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