DE4442425A1 - Combustion chamber of a burner for a vehicle heater or for an exhaust gas particle filter - Google Patents

Abstract

A combustion chamber (2) of a burner for a vehicle heater or for the thermal regeneration of an exhaust gas particle filter having a frontal boundary wall (4), a circumferential boundary wall (8), a connector (12) for fitting a glow plug and a connector for conveying combustion air which projects from the frontal boundary wall (4) into the combustion chamber and has at least combustion air outlets (18; 42) through the connector wall, in which the combustion chamber (2) with the frontal boundary wall, the circumferential boundary wall (8), the glow plug connector (12) and with or without the air supply connector (10) takes the form of a one-piece precision-cast component.

Description

The invention relates to the combustion chamber of a burner for a Vehicle heater or for thermal regeneration of an exhaust gas particle filter, one end boundary wall, one peripheral boundary wall, a nozzle for accommodating a glow plug and has a nozzle for supplying combustion air from the Forehead boundary wall protrudes into the combustion chamber and at least Combustion air exits through the nozzle wall.

Such combustion chambers of burners for the named areas of application are known. The well-known combustion chambers have been punched out and then bent sheet metal parts put together, which is considerable Effort for connecting the items, usually through Welding or soldering. These joining techniques pull in usually a heat distortion of the combustion chamber, so that the Combustion chamber must be adjusted before installation in the burner got to.

The invention has for its object to produce a more rational To make the combustion chamber available.

To solve this problem, the combustion chamber with the end boundary wall, with the circumferential boundary wall with which Glow plug socket, and with or without the air supply socket as one-piece investment casting component formed.

Investment casting is a known manufacturing process. Of the Training of a combustion chamber as an investment casting component, however, stood up general view of the technical field in the field of the invention contrary to the fact that only the "sheet metal construction" mentioned is suitable,  Combustion chambers made of suitable materials and in the desired one to be able to produce thin wall thickness of the components. The inventors of the present subject matter have raised these concerns ignored and found that after the Investment casting contrary to expectations, combustion chambers make sense small wall thicknesses and can be produced from a suitable material. The Manufacturing accuracy is better than that when it comes to communication Sheet metal construction. There are at most minimal postprocessing, e.g. B. Drill fuel hole required.

The invention gives the possibility of the investment casting integral construction To drive the combustion chamber very far or less. With inclusion of the air supply nozzle in the integral construction results particularly high rationalization effect. But also an investment casting component, into which the air supply nozzle, which in turn is either made bent sheet metal or is manufactured using the investment casting process, is used later, already brings advantages over the conventional design. The further description makes it clear be that in further development of the invention even more Functional components of the combustion chamber in the investment casting integral design can involve.

A typical representative of the invention preferred Investment casting technology is the lost wax technique. In this method, a manufacturing mold for a Wax model, which is the shape of the one ultimately to be manufactured Investment casting component has made. A larger number of these Wax models are then connected to a common one Pouring channel, in one - often made of ceramic particles with binder existing - molded material. During the subsequent pouring melt the wax models and become the resultant Mold cavities filled with liquid metal. To demold the Investment casting components will destroy the molding material.  

As a material for the investment casting component according to the invention scaling-resistant and heat-resistant steel alloys preferred, especially steel alloys from the group of stainless steel.

Preferably, the glow plug socket is at least essentially aligned parallel to the longitudinal direction of the combustion chamber and formed as a bulge of the circumferential boundary wall. in the Cross-section, the bulge can have a part-circular shape, especially a substantially semicircular or between semicircular and three-quarter circular shape. In The glow plug socket is normally in the longitudinal direction shorter than the circumferential boundary wall.

The air supply nozzle can at its downstream end open to the inside of the combustion chamber (which creates an end Combustion air escapes) or closed at this end be (so that it only exits the combustion air through the nozzle wall having). In the former case, it is preferred to flow downstream from the said open end to arrange a flame holder, the Combustion air flow emerging from the open end to the outside towards the circumferential boundary wall so that it is there provides the oxygen to completely burn the fuel. The flame holder is preferably one for the air supply nozzle towards convex curved plate. The flame holder can be a separate subsequently attached component, but can also be part of the investment casting component mentioned earlier.

In many cases it is desirable that the combustion chamber have one Mounting flange for their attachment in the overall burner has, the mounting flange in most cases transverse to The longitudinal direction of the combustion chamber extends. Preferably the investment casting component mentioned has the mounting flange in one piece. In terms of manufacturing technology, it is the cheapest if the mounting flange at least essentially in continuation of the End wall is located radially outwards.  

So far, the air supply nozzle has been tubular throughout distributed perforations formed in the nozzle wall. After one second aspect of the invention has the air supply nozzle Longitudinal slots in the nozzle wall as combustion air outlets. A Part of the longitudinal slots or all longitudinal slots extend to downstream end of the air supply nozzle. The Longitudinal slots are much easier with precision casting technology producible as bore-like openings in the nozzle wall. The Providing longitudinal slots does not preclude that, however bore-like combustion air outlets in the nozzle wall available.

It is expressly pointed out that the described Configuration of the air supply nozzle with longitudinal slots on the one hand a preferred development of the first aspect described above the invention ("combustion chamber in precision casting technology"), especially because an air supply nozzle with longitudinal slots in Investment casting technology is more convenient to manufacture, but on the other hand the described second aspect of the invention an independent invention represents that also detached from the idea of investment casting technology is technically advantageous.

One longitudinal slot, several longitudinal slots or all longitudinal slots can - Measured in the circumferential direction of the air supply nozzle - one over the width of the slot is constant. But it is also possible that one, several or all longitudinal slots - measured in Circumferential direction of the air supply nozzle - one over the Slit longitudinal direction increasing towards the downstream end Have width. The latter measure leads to the welcome Result that at the upstream end of the combustion chamber relatively little combustion air from the air supply nozzle in the Combustion chamber enters the combustion chamber while more to downstream end of the air supply nozzle a relative larger amount of combustion air in the combustion chamber Combustion chamber passes over there for the complete combustion of the Combustion air is available. This is an example of that  Situation that you have the downstream end of the air supply Can form closed stub because sufficiently large Air outlet cross sections in the downstream end area of the Air supply nozzle through the nozzle wall are available.

In a preferred development of the invention, at least one of the Combustion air escapes through the nozzle wall in such a way that the combustion air with flow component in the circumferential direction of the Air supply nozzle flows out. With this one reaches - for the The combustion process of the fuel in the combustion chamber is favorable - an exit of the combustion air is not essentially radial Direction, but with more or less pronounced Flow component in the circumferential direction, so that in the Combustion chamber gives a swirl flow.

It is further preferred to have the air supply nozzle with an in Form flow direction tapering inner cross section. As a result, the hot, expanding combustion gases in the annular combustion chamber between the circumferential Boundary wall and the air supply nozzle one in Flow direction increasing flow cross-section available posed.

The combustion chamber according to the invention is preferably as Evaporation combustion chamber formed. For this purpose you can on the inside of the end boundary wall and / or the peripheral boundary wall a porous lining to evaporate the Provide fuel. The lining does not have to Boundary wall and / or the peripheral boundary wall completely cover up. Porous lining can, but does not have to, even inside of the glow plug socket. Conventional materials for the porous lining is non-woven, in particular ceramic Fibers, or fiber metal materials. It is understood that the porous Lining is fed from the outside, the fuel from the lining evaporates into the combustion chamber.  

According to a third aspect of the invention is a combustion chamber provided, the lining of which is made of sintered metal. This third Aspect of the invention is a preferred embodiment of the represents the invention described above, but on the other hand also represents a independent invention, which detached from the in the characteristic Part of the investment casting technology specified can be advantageously implemented. A porous lining made of sintered metal is much more durable than a ceramic fiber fleece, can with very uniform porosity and high accuracy of fit are produced, and provides an optimal wall contact to the concerned Combustion chamber wall. It is also possible to use one for the lining same or a similar material as for the rest Use functional components of the combustion chamber, so that the Recycling the combustion chamber is made easier. After all, you can be comfortable the thickness of the liner may vary from location to location as needed.

According to a preferred development of the invention, the Sintered metal lining can be generated in situ in the combustion chamber, by the material of the lining, d. H. the ones to be sintered Introduces particles into the combustion chamber in the unsintered state and sintered there in place. Usually used for this purpose a core is inserted into the combustion chamber, so that a gap-shaped Shaping space between the end wall or the front Circumferential boundary wall and the core arises in which the to sintering particles can be filled. Sintering takes place in usual way by supplying heat. Sintering in situ provides optimal contact between the lining and the concerned Boundary wall of the combustion chamber.

According to a fourth aspect of the invention, the circumferential Boundary wall and the air supply nozzle a guide and Protective ring from the front boundary wall a bit to Inside the combustion chamber arranged protruding. The guide and protection ring causes a more axial flow in the upstream End area emerging from the air supply nozzle Combustion air and - what is particularly important - prevents one  Drop of unburned fuel on the hot during operation Air supply nozzle with the significant risk of coking the Air supply nozzle up to partial or complete Closing combustion air leaks, which is a danger pulls that the combustion of the fuel is no longer properly expires.

It is expressly pointed out that this fourth aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand an independent invention, detached from im characterizing part of claim 1 specified investment casting component Thoughts, because the training according to the fourth aspect of The invention can also be used technically advantageously independently of this.

The guide and protection ring does not necessarily have to extend over 360 ° his. With lower requirements, it may be sufficient if it turns out to be Partial ring extends over a partial circumference of the combustion chamber, especially where there is a drop of fuel on the Air supply nozzle is most likely to be expected.

The downstream end area of the guide and guard ring is preferably designed so that it increases turbulence on the Combustion air flow acts, i.e. the mixing of evaporates fuel and combustion air.

The combustion chamber according to the invention can - with the exception of Glow plug socket - essentially a cylindrical end view Configuration, but it does not have to be.

According to a fifth aspect of the invention, this is the forehead Boundary wall of the combustion chamber near the end of the lining and / or that which is more distant from the end boundary wall of the combustion chamber End of the lining in a circumferential continuous or in Sections of interrupted annular gap set. Based on these Training, the lining can be extremely technical  simply attach in the combustion chamber. You can go so far that the number of previously common welding points for fastening the Lining in the combustion chamber can be significantly reduced or there is no need for welding spots. To form the Annular gap can preferably be a circumferential continuous or in Sections of interrupted fixing ring or a component can be provided, which attaches to a flame tube continuing the combustion chamber is.

It is expressly pointed out that this fifth aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand, represents an independent invention, detached from im characterizing part of claim 1 specified Investment casting thoughts because the training according to the fifth aspect the invention also technically advantageous regardless of this is feasible.

The fixing ring is preferably for that of the end boundary wall closer end of the lining part of the investment casting component. The Fixing the position of the lining can be perfected in that the fixing ring at least at its free end after the Inserting the liner will bend on the liner, causing itself the lining is jammed. For this purpose it can be cheap, the fixing ring at its free end with thinner Form wall thickness so that it can be bent well there. The Turning is also in the case of the fixing ring broken into sections particularly relieved.

Inserting the end of the liner into the annular space is particularly easy if - seen in longitudinal section - itself this space tapers towards its end and / or the Lining has a tapered end. It is just with the Fastening the liner according to the fifth aspect of the invention particularly preferred, the lining only on the circumferential Provide boundary wall of the combustion chamber so that the lining  overall a tubular rather than a pot-shaped configuration Has.

According to a sixth aspect of the invention, the circumferential boundary wall the inside of the combustion chamber Longitudinal direction of the combustion chamber extending projection for the positive determination of the lining against movement in Circumferential direction. In this way, the definition in Circumferential direction not from the remaining position fixation of the lining be performed. It is also achieved that the lining only in a certain position (related to rotation around the Longitudinal axis of the combustion chamber) can be brought into the combustion chamber, so that z. B. an opening in the liner opposite the nozzle should be positioned for the glow plug, automatically in the right place is coming.

It is expressly pointed out that this sixth aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand, represents an independent invention, detached from im characterizing part of claim 1 specified Investment casting component ideas, because the training according to the sixth Aspect of the invention also technically advantageous regardless of this is feasible.

According to a seventh aspect of the invention is in the flow path Combustion air in front of the air supply nozzle a device for Generation of flow swirl provided. The twisted one Combustion air flow leads to a more optimal formation of a combustible fuel-air mixture.

It is expressly pointed out that this seventh aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand, represents an independent invention, detached from im characterizing part of claim 1 specified  Investment casting idea, because the training according to the seventh aspect the invention also technically advantageous regardless of this is feasible.

The device for generating flow swirl is preferably at least largely part of the investment casting component or at least for the most part part of the housing of a combustion chamber Combustion air blower. The device can in particular one Leitapparat, a flow space delimited spirally on the circumference or the like.

According to an eighth aspect of the invention, the transition between the Circumferential boundary wall of the combustion chamber and the liner Fuel distribution channel provided, which extends over at least part of the circumference of the circumferential boundary wall. By the Fuel distribution channel is achieved that the fuel supplied already distributed on the back of the lining over a larger area. A more uniform evaporation of the fuel over a larger one Area of the lining and a reduction in the risk of This results in fuel dripping from the lining.

It is expressly pointed out that this eighth aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand, represents an independent invention, detached from im characterizing part of claim 1 specified Investment casting component ideas, because the training according to the eighth aspect the invention also technically advantageous regardless of this is feasible.

Preferably, one opens into the fuel distribution channel Fuel supply nozzle for fuel supply essentially in Provided circumferential direction. By such Fuel supply neck will achieve the above further promoted advantages.  

According to a ninth aspect of the invention is radially further out than that Circumferential boundary wall of the combustion chamber a thermal finger provided, the end of which in the longitudinal direction Combustion chamber is further forward than its root, and is at the Outside of the combustion chamber component in the area where the Inside the combustion chamber component, the root of the thermal finger is set a temperature sensor with which it can be detected whether in the combustion chamber combustion or not.

Burners for vehicle heaters or for thermal regeneration of Exhaust gas particle filters have so far usually been equipped with one so-called flame detection or flame termination detection equipped. If it is determined with the aid of this device that inadvertently no combustion process in the combustion chamber or no more combustion process takes place, at least that Supply of fuel to the combustion chamber interrupted, so here not uncontrolled accumulations of unburned fuel arise. So far, you usually have on the wall for this purpose of the heat exchanger downstream of the combustion chamber Temperature sensor provided due to falling wall temperature recognizes the flame arrest. However, this technique requires that Drilling a hole through the outer wall of the heat exchanger; especially in the case of a combustion gas / water heat exchanger there are sealing and corrosion problems.

According to the ninth aspect of the invention, the mounting location of the Temperature sensor shifted to the combustion chamber component; it results a significantly simplified production, and problems of the described Kind are avoided. Preferably, the thermal finger Part of the investment casting component.

It is expressly pointed out that the ninth aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand, represents an independent invention, detached from in characterizing part of claim 1 specified  Investment casting component ideas because the training according to the ninth Aspect of the invention also technically advantageous regardless of this is feasible.

According to a tenth aspect of the invention, from the surfaces that tend to build up carbon-containing deposits during operation, at least a part made of copper. From the surfaces that for copper-containing training are in particular those called the following: inside of the lining to evaporate the Fuel, outside of the air supply nozzle, inside of the Nozzle for the glow plug, boundary walls of the combustion chamber (especially if or where there is no lining) that the Combustion chamber downstream flame tube, surface on the combustion gas side of the heat exchanger.

Despite all constructive efforts, there are combustion chambers sometimes areas with lack of oxygen, in which there is too carbonaceous deposits can come. Because of the copper Training is the combustion temperature of such deposits very greatly reduced (a reduction to 200 to 250 ° C is reachable). Because such temperatures are particularly not only short-term operation can be achieved anywhere in the combustion chamber, one observes a self-cleaning effect. Keeping the Surfaces of the type of carbonaceous deposits mentioned important for trouble-free operation and long life of the Combustion chamber.

It is expressly pointed out that this tenth aspect of the Invention on the one hand a preferred embodiment of individual or represents several of the inventive aspects described above, but on the other hand, represents an independent invention, detached from im characterizing part of claim 1 specified Investment casting component ideas because the training according to the tenth Aspect of the invention also technically advantageous regardless of this is feasible.  

There is a whole range for the practical realization of copper content A range of technical options. One can use copper-containing alloys choose or provide a coating with copper-containing material. In the case of a fibrous lining to evaporate the fuel you can use the lining material fibers made of copper-containing material add. In the case of a sintered metal lining to evaporate the Fuel can be made from particles to be sintered Add copper-containing material. The term used above "Copper-containing material" also includes pure copper and Copper alloys.

The combustion chamber according to the invention is preferably part of a Burner for a vehicle heater or part of a burner for the Thermal regeneration of an exhaust gas particle filter. Vehicle heaters are used especially for passenger cars, the cabins of Trucks, buses, sailing and motor boats, construction machinery, Mobile homes, camping trailers and the like are used. In many In some cases, the vehicle has an internal combustion engine as the drive. In In this case, the vehicle heater in the coolant circuit and the regular heating circuit of the internal combustion engine be, so that the vehicle heater as an additional heater when insufficient Heat supply of the internal combustion engine and / or as auxiliary heating stationary internal combustion engine can be used. - Exhaust gas particle filter are increasingly used in the exhaust line from stationary or installed by diesel engines serving the vehicle drive. The Particle filter, often also called "soot filter" for simplicity, retain the particles contained in the exhaust gas from diesel engines. The Particulate filters, usually at intervals, must be removed from the filtered particles are freed, which in particular by thermal regeneration can happen. For thermal regeneration the gas flow flowing into the particle filter becomes so strong heated that the ignition temperature of the particles from about 650 to 700 ° C is reached and the particles with in the supplied gas stream contained oxygen are burned.

It should also be noted that contained in the subclaims independently protectable features despite the formal  Reference to the independent claim corresponding to the main claim Should have protection. Otherwise, all fall into the whole Application documents contained inventive features in the Scope of the invention.

The invention and preferred embodiments of the invention will be in the following with reference to exemplary embodiments shown in the drawings explained in more detail. It shows:

Fig. 1 is a combustion chamber in longitudinal section;

Figures 2 to 5 each in longitudinal section and somewhat more schematically a combustion chamber component, wherein alternative designs of the combustion air nozzle are drawn.

FIGS. 6 and 7 show two further alternative embodiments of the combustion air nozzle in cross-section;

Figure 8 to 12 Various embodiments of a control and protection ring in a developed in the plane view.

FIG. 13 is a combustion chamber of the other embodiment in longitudinal section, with two different variants are drawn up and down;

FIG. 14 shows a cross section along AA of the combustion chamber of FIG. 13;

Fig. 15 is a modification of the combustion chamber of Fig. 13 in a longitudinal section showing part of the combustion chamber;

Fig. 16 shows another modification of the combustion chamber of Fig. 13 in a longitudinal section showing a part of the combustion chamber;

Fig. 17 shows a vehicle heater with a combustion chamber component of another embodiment in longitudinal section.

In all embodiments, the same or analog parts uses the same reference numerals.

The combustion chamber 2 shown in Fig. 1 consists essentially of a flat end boundary wall 4 , which merges radially on the outside into a mounting flange 6 , a cylindrical peripheral boundary wall 8 , which extends from the end boundary wall 4 at right angles, one centrally from the end boundary wall 4, which carries rectangular air supply stub 10 at right angles and a glow plug stub 12 . The mounting flange 6 has a circular outer circumference. The air supply nozzle 10 is concentric to the circumferential boundary wall 8 , but smaller in diameter than the circumferential boundary wall 8 , so that an annular space is formed between the air supply nozzle 10 and the circumferential boundary wall 8 .

The longitudinal central axis of the combustion chamber 2 is designated 14 . Measured in the axial direction, the air supply nozzle 10 is approximately half as long as the circumferential boundary wall 8 . Viewed in the cross-section not shown, the glow plug socket 12 has a part-circular inner contour that extends over approximately 240 °. The partial circumferential wall of the glow plug connector 12 as it provides a bulge of the circumferential limiting wall 8 is, the circumferential limiting wall 8 where the glow plug socket joins 12, is interrupted. The glow plug socket 12 does not extend to the right up to the end of the circumferential boundary wall 8 . The longitudinal central axis 16 of the glow plug socket 12 lies somewhat outside the circumferential boundary wall 8 and is parallel to the axis 14 . The wall of the air supply nozzle 10 has circumferentially distributed and in two rows axially next to one another radial, round holes 18 as combustion air outlets.

At the downstream, in Fig. 1 right end of the air supply nozzle 10 , several webs 20 are provided distributed over the circumference in an axial continuation. At the upstream, left in FIG. 1 and downstream, right in FIG. 1 end (ie the beginning of the webs 20 ), the air supply nozzle 10 is open.

All previously mentioned parts of the combustion chamber 2 are formed together as an integral investment casting component. However, it is pointed out that the air supply nozzle 10 can alternatively also be manufactured separately and then combined with the investment casting component.

An essentially cylindrical air supply housing 19 is attached to the left of the end boundary wall 4 and may, but does not have to, contain a guide device for generating a swirl flow entering the air supply connection piece 10 . A fan, not shown, is connected to the air supply housing 19 and supplies the combustion air with the required excess pressure.

From the right against the free ends of the webs 20 , a plate 22 , which is convexly curved towards the left, is arranged as a flame holder, which is pulled against the webs 20 by means of a central-axially extending, small rod 24 . At the left end, the small rod 24 passes through the end end wall of the air supply housing 19 and is fastened there by a screwed nut 26 . The curved plate is made of sheet metal. But it could also be integrated with the webs 20 in the investment casting component; in this case the small rod 24 would be unnecessary.

Further, it can be seen in Fig. 1 is a porous lining 28 on the inside of the front limiting wall 4 and the inside of the circumferential limiting wall 8. The porous lining 28 is preferably made of sintered metal and has preferably been sintered in situ there. In the axial direction, the lining 28 is somewhat shorter than the circumferential boundary wall 8 in the embodiment shown, but could also be the same length or even longer than the circumferential boundary wall 8 . In the area where the interior of the glow plug socket 12 merges into the interior of the combustion chamber 2 , ie the annular space between the peripheral boundary wall 8 and the air supply socket 10 , the lining 28 has an opening 30 which is only of a size has a fraction of the size of the interruption of the peripheral boundary wall 8 there, but can also have practically the entire size of the interruption. When the combustion chamber 2 is installed in the overall burner, the area of a glow plug that glows when the current passes through, whether it be a glow plug with a filament or a glow plug, is accommodated in the glow plug socket 12 .

Finally, a guide and protective ring 32 can be seen in FIG. 1, which projects at right angles from the end boundary wall 4 to the right into the annular space between the circumferential boundary wall 8 and the air supply connector 10 . The axial length of the ring 32 is 5 to 30%, preferably 8 to 20%, of the axial length of the air supply connector 10 . The ring 32 is preferably in one piece with the investment casting component.

The top left in Fig. 1 nor an oblique angle of 45 ° bore 34 is provided for supplying fuel, wherein a non-drawn in stub can be press-fitted into the bore 34. In reality, the bore 34 is rotated by 150 ° with respect to the position shown next to the glow plug socket 12 .

Most of the time, the combustion chamber 2 is installed with the glow plug socket 12 on top, that is, rotated by 180 ° about its longitudinal axis 14 in comparison to FIG. 1.

In operation, the described combustion chamber 2 works as follows:
Fuel, ie generally diesel fuel or gasoline, is fed to the lining 28 via a metering pump and through the bore 34 . To start the combustion chamber 2 , the glow plug (not shown ) is supplied with current, whereupon it begins to glow in its front area. Supported by the heating by means of the glow plug, fuel evaporates from the lining 28 towards the interior of the combustion chamber 2 , but also into the interior of the glow plug socket 12 . The ignition of the fuel-air mixture then takes place on the glow plug, and the flame that is generated propagates through the opening 30 into the annular space between the circumferential boundary wall 8 and the air supply nozzle 10 . At the same time, combustion air flows out of the air supply housing 20 through the air supply nozzle 10 and from there through the radial holes 18 into the described annular space, where the initial combustion of the fuel-air mixture takes place. Further downstream, the main part of the combustion air flows out through the large spaces between the webs 20 into the combustion chamber of the combustion chamber 2 . The complete combustion of the fuel takes place there and further downstream. The guide and protective ring 32 creates a low-flow ring pocket radially outside of this, in which a rich fuel-air mixture can form. Fuel dripping downward from the lining 28 reaches the ring 32 instead of the air supply nozzle 10 and is torn away downstream by the combustion air from the right-hand downstream edge in FIG. 1.

The glow plug socket 12 can also have a small opening (not shown) for supplying a small amount of purge air.

A construction of the air supply nozzle 10 is illustrated in FIG. 2, in which instead of the round holes 18, longitudinal slots 40 are provided, which start a bit behind the upstream end of the nozzle 10 and go through to the downstream end of the nozzle 10 . The longitudinal slots 40 are evenly distributed over the circumference of the socket 10 and — measured in the circumferential direction of the socket 10 — have a width 42 that is constant over the axial direction. A flat or curved plate can be placed directly on the downstream end of the connector 10 , corresponding to the plate 22 of FIG. 1. Alternatively, in the axial extension of the connector 10, webs 20 can be cast on, as in the embodiment of FIG. 1; the plate, not shown, would then rest against the free ends of these webs 20 .

In Fig. 3, a variant is shown, in which the longitudinal slots - have a progressively increasing width in the flow direction 42 - measured in the circumferential direction of the nozzle 10.

In the variant shown in FIG. 4, the nozzle 10 tapers conically in the direction of flow.

In Fig. 5 a variant is shown, in which the taper of the sleeve extends inwardly curved 10.

In Figs. 6 and 7, embodiments of the nozzle 10 are drawn in cross-section, in which longitudinal slots 40 and nozzle wall portions 44 alternate with each other. The longitudinal slots 40 are shaped so that they force a combustion air outlet with flow component in the circumferential direction of the nozzle 10 .

In all of the exemplary embodiments according to FIGS. 2 to 7, as in the exemplary embodiment according to FIG. 1, the end boundary wall 4 , the circumferential boundary wall 8 , the fastening flange 6 , the air supply nozzle 10 and the glow plug nozzle 12 are formed as a one-piece investment casting component .

Various variants of the design of the guide and protective ring 32 are illustrated in FIGS. 8 to 12. In the embodiments according to FIGS. 8 to 10, the downstream end edge of the ring 18 is profiled so that the part of the combustion air flowing there is given turbulence or its turbulence is increased. Fig. 11 shows a design of the downstream end of the ring 32 as a sharply pointed, outwardly bent Abspritzkante.

FIG. 12 shows an embodiment of the ring with inclined grooves or projections on the inside in order to impart swirl to the air flowing there. Corresponding grooves or protrusions could be provided on the outside of the ring 32 for guiding spilled fuel in the spiral direction. The ring 32 need not be cylindrical, but could also be conical, tapering or widening in the downstream direction.

The combustion chamber 2 shown in FIGS. 13 and 14, as far as analogous to the combustion chamber 2 of FIG. 1, has a flat end boundary wall 4 , a cylindrical circumferential boundary wall 8 , a cylindrical air supply nozzle 10 , a glow plug nozzle 12 , and a fastening flange 6 , which, however, goes further to the right of the circumferential boundary wall 8 radially outwards than in the embodiment of FIG. 1. As in the embodiment of FIG. 2, the air supply socket is designed with longitudinal slots 40 . All previously mentioned parts of the combustion chamber 2 are formed together as an integral investment casting component. However, it is pointed out that the air supply nozzle 10 can alternatively also be manufactured separately and then combined with the investment casting component.

In contrast to the embodiment of FIG. 1, the combustion chamber 2 of FIGS. 13 and 14 has a guide device for generating flow swirl in the combustion air flowing to the air supply nozzle 10 , the curved guide vanes 50 of which are cast integrally with the investment casting component of the combustion chamber. The guide vanes 50 occupy somewhat less than the space of the end boundary wall 4 in the radial direction and project directly from this axially to the left in FIG. 13. On the side facing away from the end boundary wall 4 , the guide vanes 50 are formed by a circular, continuous plate 52 covered, so that the combustion air must flow from the radially outside into the flow channels between the guide vanes 50 and enters the air supply nozzle 10 with a very considerable swirl about the longitudinal central axis 14 of the combustion chamber 2 . The plate 52 can also be cast integrally with the investment casting component, but can alternatively also be a separately manufactured, subsequently attached and fastened part.

Alternatively, the device for generating flow swirl can preferably be formed by a flow space with a spiral-like circumferential wall, which is placed in front of the air supply nozzle 10 . The combustion air can be fed tangentially to this flow space on the circumferential wall that runs with a smaller radius of curvature. The flow space described can in a correspondingly thick housing wall of a combustion air blower placed in front of the combustion chamber 32 , see e.g. B. housing wall 80 in FIG. 17.

Fig. 13 also shows a novel attachment of the porous liner 28 in the combustor 2. First of all, it should be pointed out that the lining 28 is purely cylindrical and thus not cup-shaped, as in the embodiment of FIG. 1; the lining 28 is therefore provided on the inside on the circumferential boundary wall 8 , but not on the inside on the end boundary wall 4 . In FIG. 13 to the right, a fixing ring 54 projects from the end boundary wall 4 towards the interior of the combustion chamber 2 , namely with a radial distance to the inside of the peripheral boundary wall 8 , which essentially corresponds to the radial thickness of the lining 28 . The left end of the liner 28 in FIG. 13 is inserted into the annular gap 56 thus formed between the circumferential boundary wall 8 and the fixing ring 54 , the fixing ring 54 being slightly bevelled on the outside on the right to facilitate insertion.

With regard to the fastening of the right end of the lining 28 in FIG. 13, two different variants are drawn in FIG. 1 above the longitudinal central axis 14 and below the longitudinal central axis 14 . To the right, a flame tube 58 made of sheet metal is attached to the investment casting component of the combustion chamber 2 , which is shown in broken lines in FIG. 13, but in reality is considerably longer in the axial direction than the combustion chamber 2 . A piece away from its left end is fixed in the flame tube 58 a flame shield 60 , which is made of sheet metal and has a large central flow opening 62 , which constricts the gas flow compared to the inner diameter of the circumferential boundary wall 8 or the flame tube 58 locally.

In the variant above in FIG. 13, the flame shield 60 is bent at the transition for fastening in the flame tube 58 in such a way that an annular gap 64 remains between the flame tube 58 and an area 66 of the flame shield which runs essentially parallel to the flame tube 58 . The right end of the lining 28 in FIG. 13 is pushed into this annular gap 64 , so that the described region 66 of the flame shield 60 acts as a fixing ring for the lining 28 . The liner 28 is relatively long in the axial direction, that is, it leads a little way out of the circumferential boundary wall 8 into the flame tube 58 .

In the variant below in FIG. 13, the lining 28 ends on the right before the end of the circumferential boundary wall 8 is reached. In the left end region of the flame tube 58 in FIG. 13, a ring-like component 68 is fastened to it, which projects to the left and is bent inwards at the left end so that there is an annular gap 64 (analogous to the annular gap 64 above in FIG. 13). is formed to receive the right end of the liner 28 .

If the flame tube component 58 is pushed to the left onto the combustion chamber component 2 and is fastened there by welding, the right end of the lining 28 is also received in the relevant annular gap 64 , as described. The lining 28 is fixed on the inner circumference of the circumferential boundary wall 8 because of the two-sided locking. The radial dimensions of the annular gaps 56 and 64 can, but need not, be such that the ends of the lining 28 are received with a certain degree of clamping; to facilitate assembly, the ends of the liner 28 can be formed with a chamfer on the inside. It is also pointed out that the lining 28 does not necessarily have to be fixed at both ends. In particular with a relatively stiff consistency and / or if the lining 28 is not too long in the axial direction, it can be sufficient to fix it to only one axial end. In this case, however, there should preferably be a real position fixation z. B. done by clamping.

As far as the attachment of the flame holder plate 22 is concerned, the webs 20 are widened radially inwards at their free end, so that the plate 22 can be easily welded there.

In Fig. 14 it can be seen that the lining 28 is cylindrical overall, but at one point on its circumference has a continuous slot in the axial and radial directions. Correspondingly, a projection 70 extending in the axial longitudinal direction of the combustion chamber 2 is provided on the inside of the circumferential boundary wall 8 . When the liner 28 is inserted axially, the projection 70 ensures that the liner 28 is oriented in a specific position with respect to its angular position about the longitudinal central axis 14 and that the liner 28 is fixed in terms of circumferential displacements. The aforementioned alignment ensures that the opening 30 of the liner 28 is in the correct position relative to the nozzle 12 for the glow plug. It should be noted that the slot in the liner 28 does not have to go completely through in the radial direction, but z. B. only one axially extending groove can be provided in the outside of the lining. Furthermore, it is alternatively possible to provide the lining with an axially extending projection on the outside and accordingly to provide an axially extending groove on the inside of the peripheral boundary wall 8 .

In Figs. 13 and 14 can also be seen that a extending in the circumferential direction Brennstoffverteilkanal is present on the inside of the circumferential limiting wall 8 72, is formed of the groove-like flat-by a depression in the material of the combustor component. In the illustrated embodiment, the distribution channel 72 runs in a circle practically over the entire circumference. However, it is also possible to provide the distribution channel 72 only for a part of the circumference, in particular for the part of the circumference from the fuel feed connector 74 to be described below to the area of the connector 12 for the glow plug or the opening 30 in the lining 28 . It is pointed out that it is alternatively possible to form the distribution channel 72 on the outer circumference of the lining 28 instead of in the material of the combustion chamber component.

The fuel feed connector 74 cast onto the combustion chamber component has an orientation essentially in the circumferential direction of the circumferential boundary wall 8 . As a result, fuel is supplied in such a direction that it continues to flow smoothly in the distribution channel 72 and enters the lining 28 from behind over a larger area.

Finally, attention is drawn to the fact that in the embodiment according to FIGS. 13 and 14, unlike in the embodiment according to FIG. 1, the connector 12 for the glow plug has such an orientation that its longitudinal central axis 16 lies essentially or exactly in one plane , which extends at right angles to the longitudinal central axis 14 of the combustion chamber 2 (drawing plane of FIG. 14).

Fig. 15 shows a modification in which the fixing ring 54 is formed in its right, free end portion with a relatively small wall thickness and has been bent after insertion of the end of the liner 28 radially-outwardly to clamp the lining 28. In this case, the annular gap 56 can easily be somewhat larger in the radial direction than the thickness of the lining 28 . The end portion of the fixing ring 54 can be bent without any problems by means of a tool inserted into the combustion chamber 2 from right to left. B. has an outer inclined surface for exerting the bending pressure.

In Fig. 16 an embodiment is shown, in which the liner 28 is, in turn, cup-shaped, so far, however, similar to Fig. 1. Fig. 16 illustrates the case that the the front limiting wall 4 more distant end of the liner 28 in a particularly favorable manner in an annular gap 64 is fixed. The annular gap 64 is formed between a flame tube 58 adjoining the combustion chamber 2 and a flame shield component 60 fastened to the flame tube 58 . When taking place in the axial direction of sliding of the flame tube 58 in Fig 16 right end. Of the combustor component 2 which comes in Fig. 16 right-hand end of the liner 28 in the described annular chamber 64 and the circumferential limiting wall 8 and serving between the end portion of the as fixing ring Flame shield component 60 clamped slightly bent. The flame tube 58 is welded to the combustion chamber component 2 .

A ring 32 protrudes from the end boundary wall 4 towards the interior of the combustion chamber 2 , but obliquely towards the radially outside. The inner diameter of the central opening, which is assigned to the end boundary wall 4 , of the lining 28 is slightly larger than the diameter of the ring 52 at its free end. As a result, the liner 28 could easily be pushed into the combustion chamber component 2 in the axial direction from right to left in FIG. 16. Apart from the mechanical fixation described at the right end, the lining 28 is fastened to the peripheral boundary wall 8 and to the end boundary wall 4 with a few welding spots. The described oblique course of the ring 32 has the advantage that fuel which may drip from the left end region of the lining 28 in FIG. 16 is passed on in the groove formed by the ring 32 in such a way that it does not drip onto the air supply nozzle 10 . In this respect, the ring 32 has a function very similar to that of the protective ring 32 in the exemplary embodiment according to FIG. 1.

But you can also run the ring 32 purely in the axial direction, which is easier casting. Finally, it is possible to operate with an axially extending as cast ring 32, which is bent after insertion of the liner 28 in its free end region outwardly against the liner 28th In this case, the liner 28 extends further towards the central axis 14 of the combustion chamber 2 at its left end. The ring 32 then represents a fixing ring for the lining 28 .

It is pointed out that the fixing ring 54 and / or the fixing ring 66 or 68 does not have to extend continuously over the entire circumference, but rather can be interrupted in sections spaced circumferentially. This interrupted training even has advantages when it comes to clamping the liner 28 by bending material areas.

Fig. 17 shows in schematic form a combustion chamber Feingußbauteil 2, installed in a vehicle heating device. In addition to the investment casting component, the flame tube 58 continuing the circumferential boundary wall 8 of the combustion chamber 2 , a part of the housing 80 of the combustion air blower, which is screwed to the investment casting component with the interposition of a seal 82 on its left end face, a jacket 84 of the heater, a heat exchanger wall 86 , which separates the space in which the combustion takes place from a water-flowed space inside the jacket, and an exhaust pipe 88 through which the combustion exhaust gases flow away from the heater.

From the left, outer end face in a recess of the investment casting, a temperature sensor 90 is very common, z. B. Type PT 1000 attached. The blower housing 80 has a through bore 92 at the attachment point of the temperature sensor 90 . The temperature sensor 90 is fastened by means of a spring clip 94 , which is fastened to the blower housing 80 , and pressed against the material of the investment casting component.

In the area of the investment casting component, where the recess 96 for the temperature sensor 90 is on the outside, the investment casting component has an integrally molded heat-conducting finger 98 on the inside, which extends from its root on the end wall of the investment casting component in the axial direction. In practice, the thermal finger 98 has an axial length in the range from 20 to 90% of the axial length of the circumferential boundary wall 8 .

If e.g. B. the combustion flame goes out due to a fault and therefore no more fuel is burned, the temperature in the annular space 100 drops between the circumferential boundary wall 8 or the flame tube 58 and the heat exchanger wall 86 . This drop in temperature is passed on to the location of the temperature sensor 90 by the thermal finger 98 . If the temperature falls below a certain threshold, the heater is switched off, primarily the fuel supply to the heater. With the aid of the temperature sensor 90 , it can also be seen whether the heater has ignited correctly after starting, because igniting the fuel evaporated in the combustion chamber quickly results in an increase in temperature in the annular space 100 described.

In order to create a burner for thermal regeneration of an exhaust gas particle filter, the combustion chamber ( 2 ) according to the invention, e.g. B. the combustion chamber ( 2 ) according to FIG. 1, be inserted at the end into the particle filter housing and be completed by a fuel pump and a combustion air blower to the burner. - In the case of a vehicle heater, a flame tube with a greater axial length than the combustion chamber ( 2 ) usually follows, often after an aperture-like cross-sectional constriction. At the end of the flame tube, the hot exhaust gas flow is deflected outwards by 180 ° and flows in the axial direction along the tubular partition of a heat exchanger before it is discharged to the outside via an exhaust pipe. Either water that is heated in this way in the vehicle heater or air that is heated in this way to hot air flows on the outside of the partition of the heat exchanger.

Claims (27)

1. Combustion chamber ( 2 ) of a burner for a vehicle heater or for thermal regeneration of an exhaust gas particle filter, which has an end boundary wall ( 4 ), a circumferential boundary wall ( 8 ), a nozzle ( 12 ) for accommodating a glow plug and a nozzle ( 10 ) for supplying combustion air, which projects from the end wall ( 4 ) into the combustion chamber ( 2 ) and has at least combustion air outlets ( 18 ; 42 ) through the nozzle wall, characterized in that the combustion chamber ( 2 ) with the end Boundary wall ( 4 ), with the peripheral boundary wall ( 8 ), with the glow plug socket ( 12 ), and with or without the air supply socket ( 10 ) is formed as a one-piece investment casting component. 2. Combustion chamber according to claim 1, characterized in that the glow plug socket ( 12 ) is aligned at least substantially parallel to the longitudinal direction of the combustion chamber ( 2 ) and is designed as a bulge of the circumferential boundary wall ( 8 ). 3. Combustion chamber according to claim 1 or 2, characterized in that the air supply nozzle ( 10 ) has an open towards the inside of the combustion chamber ( 2 ) end and that downstream of the open end a flame holder, preferably in the form of a curved plate ( 22nd ), is arranged. 4. Combustion chamber according to one of claims 1 to 3, characterized in that the investment casting component integrally has a mounting flange ( 6 ) of the combustion chamber ( 2 ), which is preferably in continuation of the end boundary wall ( 4 ) radially outward. 5. Combustion chamber according to one of claims 1 to 4, characterized in that up to the downstream end of the air supply nozzle ( 10 ) extending longitudinal slots ( 40 ) are provided in the nozzle wall as combustion air outlets. 6. Combustion chamber according to claim 5, characterized in that at least one of the longitudinal slots ( 40 ) - measured in the circumferential direction of the air supply nozzle ( 10 ) - a constant across the slot longitudinal direction width ( 42 ) or increasing over the slot longitudinal direction towards the downstream end Width ( 42 ). 7. Combustion chamber according to one of claims 1 to 6, characterized in that at least one of the combustion air outlets ( 18; 40 ) is designed such that the combustion air flows out with the flow component in the circumferential direction of the air supply nozzle ( 10 ). 8. Combustion chamber according to one of claims 1 to 7, characterized in that the air supply nozzle ( 10 ) tapers in the direction of flow. 9. Combustion chamber according to one of claims 1 to 8, characterized in that it has a porous lining ( 28 ) for evaporating the fuel as an evaporation combustion chamber on the inside of the end boundary wall ( 4 ) and / or the peripheral boundary wall ( 8 ). 10. Combustion chamber according to claim 9, characterized in that the lining ( 28 ) consists of sintered metal. 11. Combustion chamber according to claim 10, characterized in that the sintered metal lining ( 28 ) in the unsintered state has been introduced into the combustion chamber ( 2 ) and sintered in place. 12. Combustion chamber according to one of claims 9 to 11, characterized in that the end boundary wall ( 4 ) of the combustion chamber ( 2 ) closer end of the lining ( 28 ) and / or that of the end boundary wall ( 4 ) of the combustion chamber ( 2nd ) the distal end of the lining ( 28 ) is fixed in an annular gap ( 56 ; 64 ) which is continuous or interrupted in sections. 13. Combustion chamber according to claim 12, characterized in that to form the annular gap ( 56 ) a circumferentially continuous or interrupted in sections fixing ring ( 54 ) is provided. 14. Combustion chamber according to claim 13, characterized in that the fixing ring ( 54 ) is part of the investment casting component. 15. Combustion chamber according to claim 13 or 14, characterized in that the fixing ring ( 54 ) has been bent at least at its free end after the liner ( 28 ) has been inserted onto the liner ( 28 ). 16. Combustion chamber according to one of claims 12 to 15, characterized in that a component ( 66; 68 ) is provided for forming the annular gap ( 64 ) which is attached to a flame tube ( 58 ) adjoining the combustion chamber ( 2 ). 17. Combustion chamber according to one of claims 9 to 16, characterized in that the circumferential boundary wall ( 8 ) of the combustion chamber ( 2 ) on the inside a extending in the longitudinal direction of the combustion chamber projection ( 70 ) for positive fixing of the lining ( 28 ) against movement in the circumferential direction having. 18. Combustion chamber according to one of claims 1 to 17, characterized in that a device ( 50 ) for generating flow swirl is provided in the flow path of the combustion air in front of the air supply nozzle ( 10 ). 19. Combustion chamber according to claim 18, characterized in that the device ( 50 ) for generating flow swirl is at least largely part of the investment casting component or part of the housing ( 80 ) of a combustion air blower placed in front of the combustion chamber ( 2 ). 20. Combustion chamber according to one of claims 9 to 18, characterized in that a fuel distribution channel ( 72 ) is provided at the transition between the circumferential boundary wall ( 8 ) of the combustion chamber ( 2 ) and the lining ( 28 ), which is at least over a part the circumference of the circumferential boundary wall ( 8 ) extends. 21. Combustion chamber according to claim 20, characterized in that a fuel supply connection ( 74 ) opening into the fuel distribution channel ( 72 ) is provided for supplying fuel substantially in the circumferential direction. 22. Combustion chamber according to one of claims 1 to 21, characterized in that between the circumferential boundary wall ( 8 ) and the air supply nozzle ( 10 ) a guide and protective ring ( 32 ) from the end boundary wall ( 4 ) from one piece is arranged protruding far from the interior of the combustion chamber ( 2 ). 23. Combustion chamber according to claim 22, characterized in that the downstream end region of the guide and protective ring ( 32 ) is designed to increase turbulence. 24. Combustion chamber according to one of claims 1 to 23, characterized in that a heat conducting finger ( 98 ) is provided radially further outward than the circumferential boundary wall ( 8 ) of the combustion chamber ( 2 ), the end of which in the longitudinal direction of the combustion chamber ( 2 ) further forward as its root, and that on the outside of the combustion chamber component in the area where on the inside of the combustion chamber component is the root of the thermal finger ( 98 ), a temperature sensor ( 90 ) is attached, with which it can be determined whether combustion is taking place or not . 25. Combustion chamber according to claim 24, characterized in that the heat conducting finger ( 98 ) is part of the investment casting component. 26. Combustion chamber according to one of claims 1 to 25, characterized,  that of the surfaces that are in operation to build up Carbonaceous deposits tend to have at least a portion is designed to contain copper. 27. Combustion chamber according to claim 26, characterized in that the porous lining ( 28 ) for evaporating the fuel is coated on the inner surface with copper-containing material or, in the case of a fibrous lining, contains fibers made of copper-containing material or, in the case of a sintered metal Lining that contains particles of copper-containing material.