DE4442425B4 - Combustion chamber of a burner for a vehicle heater or for an exhaust gas particle filter - Google Patents

Abstract

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 wall ( 4), with the circumferential boundary wall (8), with the glow plug socket (12), and with the air supply socket (10) is formed as a one-piece investment casting 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, which has an end boundary wall, a circumferential boundary wall, a nozzle for housing a glow plug and a nozzle for feeding of 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 fields of application are known ( DE 42 25 749 A1 for the vehicle heater burner application area). The known combustion chambers have been assembled from stamped and then bent sheet metal parts, which means considerable effort for connecting the individual parts, usually by welding or soldering. These connection techniques usually result in heat distortion of the combustion chamber, so that the combustion chamber must be adjusted before installation in the burner.

The invention has for its object a to make the combustion chamber more efficient to produce.

To solve this problem is the Combustion chamber with the end boundary wall, with the peripheral boundary wall, with the glow plug socket, and with the air supply nozzle as one piece Feingußbauteil educated.

Investment casting is a well-known Production method. The formation of a combustion chamber as an investment casting stood, however, the one commonly used in the field of the invention Opposition of the professional world that only the "sheet metal construction" mentioned is suitable, combustion chambers Manufacture from suitable materials and in the desired thin wall thickness of the components to be able to. The inventors of the present subject matter have become aware of them Overruled concerns and found that after the investment casting process contrary to expectations, combustion chambers with sensibly small wall thicknesses and can be produced from a suitable material. The manufacturing accuracy is better without message work than with sheet metal construction. It are at most minimal post-processing, e.g. Drilling a fuel supply hole, required.

The invention gives the possibility the investment casting integral design to drive the combustion chamber very far or less. By including the Air supply nozzle The integral construction method has a particularly high rationalization effect. From the further description it will be clear that in Further development of the invention also further functional components the combustion chamber in the investment casting integral design can involve.

A typical one in the invention in itself, this is the preferred representative of investment casting technology known lost wax processes. In this process, a Production form for a wax model, which the shape of the ultimately to be manufactured Feingußbauteils has made. A larger number These wax models are then connected to a common one sprue, in one - often out ceramic particles with binder existing - molding material formed. At the subsequent to water melt the wax models and become the resultant mold cavities with liquid Filled in metal. For demoulding the investment cast components the molding material is destroyed.

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

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

The air supply nozzle can at its downstream end be open to the interior of the combustion chamber (which creates a final combustion air outlet results) or be closed at this end (so that it only the combustion air exits through the nozzle wall). in the in the former case it is preferred to flow downstream of the said open one End to arrange a flame holder that the emerging from the open end Combustion air flow to the outside towards the circumferential boundary wall so that it is there the oxygen to complete Burning the fuel supplies. The flame holder is preferred one towards the air supply nozzle convex curved Plate. The flame holder can be a separate, retrofitted component be, but can also be part of the above Feingußbauteils his.

In many cases it is desirable that the combustion chamber have a mounting flange for its mounting in the overall burner, the mounting flange in most cases transverse to the longitudinal direction of the combustion chamber runs. The investment casting component mentioned preferably has the fastening flange in one piece. From a manufacturing point of view, it is most favorable if the fastening flange is at least substantially in continuation of the end boundary wall radially outwards.

So far, you have consistently the air supply nozzle tubular with distributed perforations in the nozzle wall. After one second aspect of the invention, the air supply nozzle has longitudinal slots in the nozzle wall as combustion air outlets. A part of longitudinal slots or all longitudinal slots extend to the downstream end of the air supply nozzle. The longitudinal slots are in investment casting technology much easier to manufacture than hole-like openings in the nozzle wall. However, the provision of longitudinal slots closes not from that in addition bore-like combustion air outlets in the nozzle wall are.

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 described above Aspect of the Invention ("Combustion Chamber in investment casting technology "), in particular because an air supply nozzle with longitudinal slots in investment casting technology is easier to manufacture, but on the other hand the described second aspect of the invention is an independent invention represents that also detached of the idea of precision 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 Slit longitudinally have constant width. But it is also possible that one or more or all longitudinal slots - measured in the circumferential direction of the air supply nozzle - one over the Slit longitudinally to the downstream end have increasing width. The latter measure leads to that welcome result that on upstream end region of the Combustion chamber relatively little combustion air from the air supply nozzle enters the combustion chamber of the combustion chamber while more to the downstream end of the air supply nozzle a relatively larger amount of combustion air enters the combustion chamber of the combustion chamber and there for complete combustion of the combustion air stands. This is an example of the situation that one the downstream end of the air supply spigot closed can because enough size Air outlet cross sections in the downstream end area of the Air supply nozzle through the nozzle wall stand.

In a preferred further education of Invention is at least one of the combustion air outlets the nozzle wall formed such that the combustion air with flow component in the circumferential direction of the air supply nozzle flows. With this you reach - for the process the combustion of fuel in the combustion chamber cheap - one Combustion air does not exit essentially radially Direction, but with a more or less pronounced flow component in the circumferential direction, so that results in a swirl flow in the combustion chamber.

It is further preferred to use the air supply nozzle with a tapering in the direction of flow Form internal cross-section. This will make the hot, expanding Combustion gases in the ring Combustion chamber between the peripheral boundary wall and the air supply nozzle one in the direction of flow increasing flow cross-section to disposal posed.

The combustion chamber according to the invention is preferred designed as an evaporation combustion chamber. For this purpose you can on the inside of the end boundary wall and / or the circumferential boundary wall porous Provide a lining to evaporate the fuel. The lining does not have to the forehead boundary wall and / or completely cover the circumferential boundary wall. Porous lining can, but must not, even inside the glow plug socket be provided. conventional Materials for the porous lining are non-woven fabrics, especially made of ceramic fibers, or fiber metal materials. It is understood that the porous Lining from the outside forth fuel supplied which evaporates from the lining into the combustion chamber.

According to a third aspect of the invention a combustion chamber is provided, the lining of which is made of sintered metal consists. On the one hand, this third aspect of the invention represents a preferred embodiment of the invention described above, on the other hand, it also represents an independent invention, detached from the investment casting component technology specified in the characterizing part of claim 1 can be advantageously implemented. A porous lining made of sintered metal is much more durable than a ceramic nonwoven, can with very uniform porosity and high Made fit be, and provides an optimal wall contact to the concerned Combustion chamber wall. It is also possible for the Lining the same or a similar material as for the remaining functional components the combustion chamber so that the recycling of the combustion chamber is relieved. Finally one can conveniently change the thickness of the liner from place to place as needed vary.

According to a preferred development of the invention, the sintered metal lining can be produced in situ in the combustion chamber by inserting the material of the lining, ie the particles to be sintered, into the combustion chamber in the unsintered state always brings in and hides there on the spot. A core is normally inserted into the combustion chamber for this purpose, so that a gap-shaped shaping space is created between the end boundary wall or the peripheral boundary wall and the core, into which the particles to be sintered are filled. Sintering is carried out in the usual way by adding heat. Sintering in situ provides optimal contact between the lining and the relevant boundary wall of the combustion chamber.

According to a fourth aspect of the invention is between the perimeter wall and the air supply nozzle a guide and protection ring from the front boundary wall a bit arranged projecting to the interior of the combustion chamber. The guide and protection ring causes a more axial flow that in the upstream end area from the air supply nozzle escaping combustion air and - which is particularly important - prevented a drop of unburned fuel on the hot air supply nozzle during operation with the considerable risk of coking of the air supply nozzle up to the partial or complete closure of Combustion air leaks, which entails the risk that the combustion of the Fuel no longer runs properly.

It is expressly pointed out that this fourth aspect of the invention, on the one hand, a preferred embodiment one or more of the aspects of the invention described above represents, but on the other hand an independent invention, detached from im characterizing part of the investment casting component idea indicated, because training according to the fourth Aspect of the invention also independent of which is technically advantageous.

The guide and protection ring does not have to absolutely about 360 ° all around his. With lower requirements, it can be sufficient if it is as a partial ring over extends a partial circumference of the combustion chamber, especially where with 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 to increase turbulence on the combustion air flow works, i.e. the mixing of evaporated fuel there and promotes combustion air.

The combustion chamber according to the invention can - with one exception the glow plug neck - essentially have a cylindrical configuration in front view, but it must not necessarily.

According to a fifth aspect of the invention this is the forehead boundary wall closer to the combustion chamber End of the lining and / or that of the forehead boundary wall Combustion chamber distant end of the liner in a circumferentially continuous or defined in sections interrupted annular gap. by virtue of this training can the lining is extremely simple in terms of production technology in the combustion chamber Fasten. One can go so far that the number of usual welding spots considerably reduced for fastening the lining in the combustion chamber can be or on spot welds can be dispensed with entirely. A can preferably be used to form the annular gap circumferentially continuous or provided in sections interrupted fixing ring or a component be attached 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 represents one or more of the inventive aspects described above, but on the other hand an independent invention represents detached from the investment casting component idea specified in the characterizing part of claim 1, because the training according to the fifth aspect the invention also independent of which is technically advantageous.

The fixing ring for the front wall is preferred details End of the lining part of the investment casting. The fixation the lining can be by perfecting that the fixing ring at least at its free end after insertion the liner turns towards the liner, causing a Clamping of the lining results. For this purpose, it may be convenient form the fixing ring at its free end with a thin wall so that it is there can be turned well. The turning is also in the case of the Sections of interrupted fixation ring particularly easy.

Inserting the end of the liner in the annular gap-like space is particularly easy if - in longitudinal section seen - yourself this room to its final end tapered and / or the liner has a tapered end having. It is precisely when the lining is attached according to the fifth aspect the invention particularly preferred, the lining only on the circumferential boundary wall Provide combustion chamber so that the Liner overall a tube-like and not a pot-shaped one Configuration.

According to a sixth aspect of the invention, the circumferential boundary wall of the combustion chamber has on the inside a projection extending in the longitudinal direction of the combustion chamber for positively fixing the lining against movement in the circumferential direction. In this way, the determination in the circumferential direction does not have to be made by the remaining position fixing of the lining. In addition, it is achieved that the lining can only be introduced into the combustion chamber in a specific position (based on rotation about the longitudinal axis of the combustion chamber), so that, for example, an opening in the lining, the ge should be positioned opposite the nozzle for the glow plug, automatically comes to the right place.

It is expressly pointed out that this sixth aspect of the invention, on the one hand, a preferred embodiment one or more of the aspects of the invention described above represents but on the other hand represents an independent invention, detached from the investment casting component idea specified in the characterizing part of claim 1, because the training according to the sixth Aspect of the invention also independent of which is technically advantageous.

According to a seventh aspect of the invention is in the flow path the combustion air in front of the air supply nozzle a device for generating flow swirl intended. The swirling combustion air flow leads to a optimal formation of a combustible fuel-air mixture.

It is expressly pointed out that this Seventh aspect of the invention is a preferred embodiment one or more of the aspects of the invention described above represents but on the other hand represents an independent invention, detached of investment casting component ideas specified in the characterizing part of claim 1, because training according to the seventh Aspect of the invention also independent of which is technically advantageous.

Preferably the device for generating flow swirl at least for the most part Part of the investment casting component or at least for the most part Part of the housing one of the combustion air blowers in front of the combustion chamber. The facility can in particular a diffuser, a spiral on the circumference limited flow space or the like.

According to an eighth aspect of the invention is at the transition between the circumferential boundary wall of the combustion chamber and the liner a fuel distribution channel is provided, which is at least one Part of the circumference of the circumferential boundary wall extends. By the Fuel distribution channel is achieved that the fuel supplied already on the back from the lining over spread a larger area. A more even one Evaporation of the fuel over a larger area of the Lining and reducing the risk of draining The result is fuel from the lining.

It is expressly pointed out that this eighth aspect of the invention on the one hand a preferred embodiment one or more of the aspects of the invention described above represents but on the other hand represents an independent invention, detached from the investment casting component idea specified in the characterizing part of claim 1, because the training according to the eighth Aspect of the invention also independent of which is technically advantageous.

Preferably one is in the fuel distribution channel opening out Fuel supply connection for fuel supply provided essentially in the circumferential direction. By such Fuel supply connection the achievement of the advantages discussed above will go even further promoted.

According to a ninth aspect of the invention radially further out a heat conducting finger is provided as the peripheral boundary wall of the combustion chamber, its end in the longitudinal direction the combustion chamber is further forward than its root, and is at 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, a temperature sensor is attached, with which it can be determined whether in the combustion chamber combustion takes place or not.

Burners for vehicle heaters or for thermal So far, regeneration of exhaust gas particulate filters has been in everyone Usually equipped with a so-called flame detection or flame termination detection. If with the help of this facility it is found that unintentionally no combustion process or combustion process in the combustion chamber yet more takes place, at least the supply of fuel to the The combustion chamber is interrupted so that there are no uncontrolled accumulations of unburned fuel. So far you have for this purpose usually on the wall of the heat exchanger downstream of the combustion chamber a temperature sensor provided that the flame arrest due to falling wall temperature recognizes. However, this technique requires drilling a hole through the outer wall 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 location of the temperature sensor to the combustion chamber component relocated; there is a significantly simplified production, and problems of the kind described are avoided. Preferably is 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 represents one or more of the inventive aspects described above, but on the other hand an independent one Invention represents detached from the investment casting component idea specified in the characterizing part of claim 1, because training according to the ninth Aspect of the invention also independent of which is technically advantageous.

According to a tenth aspect of the invention, at least a part of the surfaces that tend to build up carbon-containing deposits in operation is copper-containing. Of the surfaces that come into question for copper-containing training The following may be mentioned in particular: inside of the lining for evaporating the fuel, outside of the air supply socket, inside of the socket for the glow plug, boundary walls of the combustion chamber (in particular if or where there is no lining), the flame tube downstream of the combustion chamber, combustion gas side Surface of the heat exchanger.

Despite all constructive efforts, there are in combustion chambers sometimes areas with lack of oxygen, in which carbon-containing deposits can occur. Through the copper-containing training the combustion temperature of such deposits becomes very strong reduced (a reduction to 200 to 250 ° C is achievable). Because such Temperatures everywhere in not only for short-term operation reach the combustion chamber, a self-cleaning effect is observed. Keeping the surfaces clear the type of carbonaceous deposits mentioned is 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 one or more of the aspects of the invention described above represents but on the other hand represents an independent invention, detached from the investment casting component idea specified in the characterizing part of claim 1, because training according to the tenth Aspect of the invention also independent of which is technically advantageous.

For the practical realization of the There are a number of technical options for copper content. You can choose copper-containing alloys or a coating Provide with copper-containing material. In the case of a fibrous lining for The fuel can be evaporated from the lining material fibers Mix in material containing copper. In the case of a sintered metal lining The fuel can be evaporated from the particles to be sintered Add particles of copper-containing material. The one used above Term "copper-containing Material "also closes Pure copper and copper alloys.

The combustion chamber according to the invention is preferred 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 will be especially for Passenger cars, the cabins of trucks, buses, Sailing and motor boats, construction machinery, mobile homes, camping trailers and the like used. In many cases, the vehicle has an internal combustion engine as a drive on. In this case, the vehicle heater can in the Coolant circuit and the regular Heating circuit of the internal combustion engine to be integrated, so that the vehicle heater as an additional heater with insufficient available heat of the internal combustion engine and / or as auxiliary heating when the engine is not running Internal combustion engine can be used. - Exhaust particulate filters are increasingly used in the Exhaust system from stationary or installed by diesel engines serving the vehicle drive. The particle filter, often also called "soot filter" for simplicity the particles contained in the exhaust gas from diesel engines. The Particle filter must usually at intervals, freed from the filtered particles be what happen in particular through thermal regeneration can. For thermal regeneration, the gas flow flowing into the particle filter becomes like this strongly heated that the ignition temperature the particles from about 650 to 700 ° C is reached and the particles with contained in the supplied gas stream Oxygen are burned.

It should also be noted that in the dependent claims contained independently protectable Features despite the formal reference to the main claim corresponding independent Should have protection. Furthermore all fall inventive contained in the entire application Features within the scope of the invention.

The invention and preferred embodiments the invention are illustrated below with reference to drawings Embodiments still explained in more detail. It shows:

1 a combustion chamber in longitudinal section;

2 to 5 each in longitudinal section and somewhat more schematically a combustion chamber component, alternative designs of the combustion air nozzle being drawn;

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

8th to 12 various design variants of a guide and protective ring in the view developed in the plane;

13 a combustion chamber of another embodiment in longitudinal section, two different variants being drawn above and below;

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

15 a modification of the combustion chamber from 13 in a longitudinal section showing part of the combustion chamber;

16 another modification of the combustion chamber from 13 in a longitudinal section showing part of the combustion chamber;

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

In all embodiments, the same or similar parts used the same reference numerals.

In the 1 drawn combustion chamber 2 consists essentially of a flat end wall 4 that radially outside in a mounting flange 6 passes a cylindrical circumferential boundary wall 8th by the forehead boundary wall 4 perpendicular to the right, one centrally from the forehead boundary wall 4 Right-angled to the right, cylindrical air supply nozzle 10 and a glow plug socket 12 , The mounting flange 6 has a circular outer circumference. The air supply nozzle 10 is concentric with the circumferential boundary wall 8th , but smaller in diameter than the circumferential boundary wall 8th , so that between the air supply nozzle 10 and the perimeter boundary wall 8th an annular space is formed.

The longitudinal central axis of the combustion chamber 2 is with 14 designated. The air supply nozzle is measured in the axial direction 10 about half as long as the perimeter wall 8th , Viewed in the cross-section not shown, the glow plug socket has 12 a part-circular inner contour that extends over approximately 240 °. The partial peripheral wall of the glow plug socket 12 provides a bulge of the circumferential boundary wall 8th represents, the circumferential boundary wall 8th where the glow plug socket is 12 connects, is interrupted. The glow plug socket 12 does not extend to the right up to the end of the circumferential boundary wall 8th , The longitudinal central axis 16 of the glow plug socket 12 lies somewhat outside the circumferential boundary wall 8th 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 each other radial, round holes 18 as combustion air outlets.

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

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

Left to the forehead boundary wall 4 is an essentially cylindrical air supply housing 19 attached, which is a diffuser for generating an in the air supply nozzle 10 Swirl flow may occur, but does not have to. To the air supply housing 19 a fan, not shown, is connected, which supplies the combustion air with the required overpressure.

From the right at the free ends of the webs 20 a plate is convexly curved to the left 22 arranged as a flame holder by means of a central-axial, small rod 24 against the bridges 20 is pulled. The small pole leads to the left end 24 through the end bulkhead of the air supply housing 19 and is there by a screwed nut 26 attached. The curved plate is made of sheet metal. But it could also be integral with the webs 20 be included in the investment casting; in this case the little rod would be 24 dispensable.

You can also see in 1 a porous lining 28 inside the forehead boundary wall 4 and inside the perimeter wall 8th , The porous lining 28 consists preferably of sintered metal and has preferably been sintered in situ there. The lining is in the axial direction 28 in the illustrated embodiment, somewhat shorter than the circumferential boundary wall 8th , but could also be the same length or even longer than the circumferential boundary wall 8th his. In the area where the inside of the glow plug neck 12 inside the combustion chamber 2 , ie the annular space between the circumferential boundary wall 8th and the air supply nozzle 10 , passes over, has the lining 28 an opening 30 which are only a fraction of the size of the interruption of the circumferential boundary wall in their size 8th has, but can also be practically the entire size of the interruption. With the combustion chamber built into the overall burner 2 is in the glow plug socket 12 the area of a glow plug that glows when the current passes through, be it glow plug with filament or glow plug.

Finally one recognizes in 1 a guide and protection ring 32 that is perpendicular from the forehead boundary wall 4 to the right in the annular space between the circumferential boundary wall 8th and the air supply nozzle 10 protrudes. The axial length of the ring 32 is 5 to 30%, preferably 8 to 20%, of the axial length of the air supply nozzle 10 , The ring 32 is preferably in one piece with the investment casting component.

In the top left 1 is still a 45 ° inclined hole 34 provided for the supply of fuel, being in the bore 34 a not shown nozzle with a press fit can be used. In reality, the hole is there 34 rotated by 150 ° compared to the position shown next to the glow plug socket 12 ,

Mostly the combustion chamber 2 with glow plug socket on top 12 installed, i.e. rotated by 180 ° around its longitudinal axis 14 compared to 1 ,

The described combustion chamber works in operation 2 as follows: Via a dosing pump and through the bore 34 becomes the lining 28 Fuel, ie usually diesel fuel or gasoline, supplied. To start the combustion chamber 2 the glow plug (not shown) is supplied with current, whereupon it glows in its front area starts. Supported by the heating by means of the glow plug, fuel evaporates from the lining 28 to the inside of the combustion chamber 2 but also into the inside of the glow plug socket 12 , The ignition of the fuel-air mixture then takes place at the glow plug, and the flame that forms spreads through the opening 30 in the annular space between the circumferential boundary wall 8th and the air supply nozzle 10 out. 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 in the annulus described, where the initial combustion of the fuel-air mixture takes place. The main part of the combustion air flows further downstream through the large gaps between the webs 20 out into the combustion chamber of the combustion chamber 2 , The complete combustion of the fuel takes place there and further downstream. Through the guide and protection ring 32 radially outside of this there is a low-flow ring pocket in which a rich fuel-air mixture can form. From the lining 28 fuel dripping downwards gets onto the ring 32 instead of on the air supply nozzle 10 and is from the in 1 right, downstream edge torn away by the combustion air downstream.

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

In 2 is a construction of the air supply nozzle 10 illustrates where instead of round holes 18 longitudinal slots 40 are provided, which are a bit behind the upstream end of the nozzle 10 begin and continue to the downstream end of the nozzle 10 go through. The longitudinal slots 40 are even across the circumference of the nozzle 10 distributed and have - in the circumferential direction of the nozzle 10 measured - a constant width over the axial direction 42 , On the downstream end of the nozzle 10 can be placed directly on a flat or curved plate, according to the plate 22 of 1 , Alternatively, in the axial extension of the nozzle 10 Stege 20 as in the embodiment of 1 be cast on; the plate not shown would then lie against the free ends of these webs 20 on.

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

At the in 4 drawn variant, the nozzle tapers 10 conical in the direction of flow.

In 5 is drawn a variant in which the taper of the nozzle 10 arched inwards.

In the 6 and 7 are embodiments of the nozzle 10 drawn in cross section, where longitudinal slots 40 and nozzle wall areas 44 take turns. Here are the longitudinal slots 40 shaped so that it has a combustion air outlet with flow component in the circumferential direction of the nozzle 10 force.

In all embodiments according to 2 to 7 are - as in the embodiment according to 1 - the forehead boundary wall 4 , the perimeter wall 8th , the mounting flange 6 , the air supply nozzle 10 and the glow plug socket 12 formed as a one-piece investment casting component.

In the 8th to 12 are various variants of the design of the guide and protection ring 32 illustrated. In the embodiments according to 8th to 10 is the downstream end edge of the ring 18 designed profiled so that the part of the combustion air flowing along there is given turbulence or its turbulence is increased. 11 shows a design of the downstream end of the ring 32 as a tapered, outwardly bent spray edge. 12 shows an embodiment of the ring with inclined grooves or projections on the inside to give swirl to the air flowing past. 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.

In the 13 and 14 drawn combustion chamber 2 points, as far as analogous to the combustion chamber 2 of 1 , a flat forehead boundary wall 4 , a cylindrical peripheral boundary wall 8th , a cylindrical air supply nozzle 10 , a glow plug socket 12 , and a mounting flange 6 which, however, is further to the right of the perimeter wall 8th goes radially outwards than in the embodiment of 1 , The air supply nozzle is, as in the embodiment of 2 , with longitudinal slots 40 executed. All parts of the combustion chamber mentioned so far 2 are formed together as an integral investment casting component. However, it should be noted that the air supply nozzle 10 alternatively, it can also be manufactured separately and then combined with the investment casting component.

In contrast to the embodiment of 1 points the combustion chamber 2 of 13 and 14 a diffuser for generating flow swirl in the air supply nozzle 10 incoming combustion air, whose curved guide vanes 50 are cast integrally with the investment casting component of the combustion chamber. The guide vanes 50 take up a little less in the radial direction than the space of the end boundary wall 4 and protrude axially from this directly to the left 13 , On the forehead boundary wall 4 the guide blades are on the opposite side 50 through a circular, continuous plate 52 covered, so that the combustion air only from the outside radially into the flow channels between the guide vanes 50 must flow in and with very considerable swirl about the longitudinal central axis 14 the combustion chamber 2 in the air supply nozzle 10 entry. 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 through an air supply nozzle 10 superior flow space can be formed with a spiral-like circumferential wall. 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 be in a correspondingly thick housing wall of one of the combustion chambers 32 combustion air blower in front, see eg housing wall 80 in 17 , be trained.

13 also shows a novel attachment of the porous lining 28 in the combustion chamber 2 , First of all, it should be noted that the lining 28 purely cylindrical and thus not cup-shaped as in the embodiment of 1 is; the lining 28 is on the inside of the circumferential boundary wall 8th provided, but not on the inside of the end wall 4 , In 13 protrudes to the right from the forehead boundary wall 4 a fixing ring 54 to the inside of the combustion chamber 2 there, with a radial distance to the inside of the circumferential boundary wall 8th which is essentially the radial thickness of the liner 28 equivalent. In the ring gap thus formed 56 between the circumferential boundary wall 8th and the fixing ring 54 is that in 13 left end of the liner 28 inserted, the fixing ring to facilitate insertion 54 is slightly bevelled on the outside right.

With regard to the attachment of the in 13 right end of the liner 28 are in 1 above the longitudinal central axis 14 and below the longitudinal central axis 14 drawn two different variants. At the investment casting component of the combustion chamber described 2 Continuing to the right is a flame tube made of sheet metal 58 scheduled that in 13 is drawn interrupted, but in reality in the axial direction considerably longer than the combustion chamber 2 is. A bit away from its left end is in the flame tube 58 a flame shield 60 attached, which consists of sheet metal and a large central flow opening 62 which has the gas flow compared to the inner diameter of the circumferential boundary wall 8th or the flame tube 58 constricted locally.

In the variant above in 13 is the flame shield 60 at the transition to attachment in the flame tube 58 bent so that an annular gap 64 between the flame tube 58 and one substantially parallel to the flame tube 58 trending area 66 the flame shield remains. In this ring gap 64 is that in 13 right end of the liner 28 inserted so that the described area 66 the flame shield 60 as a fixing ring for the lining 28 acts. The lining 28 is relatively long in the axial direction, so it leads out of the circumferential boundary wall 8th a little further into the flame tube 58 ,

In the variant below in 13 the lining ends 28 right before the end of the perimeter boundary wall 8th is achieved. In in 13 left end area of the flame tube 58 is a ring-like component on it 68 attached, which protrudes 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 up in 13 ) to accommodate the right end of the liner 28 is formed.

If the flame tube component 58 to the left on the combustion chamber component 2 is pushed on and fastened there by welding, is also, as described, the right end of the lining 28 in the relevant annular gap 64 added. The lining 28 is due to the two-sided locking on the inner circumference of the circumferential boundary wall 8th established. The radial dimensions of the ring gaps 56 and 64 may, but need not, be such that the ends of the lining 28 be taken up with a certain amount of trapping; For easier assembly you can use the ends of the lining 28 form with chamfer on the inside. It is also noted that the lining 28 does not have to be fixed at both ends. Especially with a relatively stiff consistency and / or a not too long design of the lining in the axial direction 28 the definition at only one axial end may be sufficient. In this case, however, a real position fixation should preferably take place there, for example by clamping.

As for the attachment of the flame holder plate 22 arrives, are the webs 20 at its free end, widened radially inwards, so that the plate 22 can be easily welded there.

In 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. Corresponding is in the axial longitudinal direction of the combustion chamber 2 running lead 70 inside the perimeter wall 8th intended. When inserting the lining axially 28 the lead ensures 70 making sure the lining 28 with regard to their angular position about the longitudinal central axis 14 is aligned in a specific position and that the liner 28 with regard to circumferential displacements. Through the mentioned alignment ensures that the opening 30 the lining 28 in the correct position relative to the nozzle 12 is 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, for example, only one axially extending channel 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, an axially extending channel on the inside of the circumferential boundary wall 8th provided.

In the 13 and 14 can also be seen that on the inside of the circumferential boundary wall 8th a fuel distribution channel running in the circumferential direction 72 is present, which is formed by a flat-groove-like depression in the material of the combustion chamber component. In the illustrated embodiment, the distribution channel runs 72 circular practically over the entire circumference. But it is also possible to use the distribution channel 72 To be provided only for a part of the circumference, in particular for the part of the circumference of the fuel supply nozzle to be described below 74 up to the area of the neck 12 for the glow plug or the opening 30 in the lining 28 , It is pointed out that it is alternatively possible to use the distribution channel 72 on the outer circumference of the lining 28 train instead of in the material of the combustion chamber component.

The fuel supply nozzle cast onto the combustion chamber component 74 has an orientation substantially in the circumferential direction of the circumferential boundary wall 8th , As a result, fuel is supplied in such a direction that it is smooth in the distribution channel 72 flows further and spread over a larger area from behind into the lining 28 entry.

Finally, attention is drawn to the fact that in the embodiment according to 13 and 14 , unlike the embodiment according to 1 , the stub 12 for the glow plug has such an orientation that its longitudinal central axis 16 is substantially or exactly in a plane that is perpendicular to the longitudinal central axis 14 the combustion chamber 2 extends (drawing level of 14 ).

15 shows a modification in which the fixing ring 54 is formed in its right, free end region with a relatively small wall thickness and after inserting the end of the lining 28 has been bent radially outwards to clamp the lining 28 , In this case, the annular gap 56 can easily be slightly larger than the thickness of the lining in the radial direction 28 , Bending the end portion of the fixation ring 54 can be easily inserted into the combustion chamber from right to left 2 introduced tool take place that has, for example, an outer inclined surface for exerting the bending pressure.

In 16 an embodiment is drawn in which the lining 28 is again pot-shaped, in this respect similar 1 , 16 however illustrates the case where the forehead boundary wall 4 more distant end of the liner 28 in a particularly favorable way in an annular gap 64 is set. The ring gap 64 is formed between one to the combustion chamber 2 subsequent flame tube 58 and one on the flame tube 58 attached flame retardant component 60 , When the flame tube is pushed open in the axial direction 58 on the in 16 right end of the combustion chamber component 2 does that come in 16 right end of the liner 28 in the described annulus 64 and is between the end portion of the circumferential boundary wall 8th and the flame shield component serving as a fixing ring 60 clamped slightly bent. The flame tube 58 with the combustion chamber component 2 welded.

From the forehead boundary wall 4 protrudes a ring 32 to the inside of the combustion chamber 2 towards, but diagonally outwards radially. The inside diameter of the central opening, that of the forehead boundary wall 4 is assigned to the lining 28 is slightly larger than the diameter of the ring 52 at its free end. As a result, the lining could 28 comfortably in the axial direction from right to left in 16 into the combustion chamber component 2 be inserted. Apart from the mechanical fixation described on the right end, the lining is 28 with a few weld spots on the peripheral boundary wall 8th and on the forehead boundary wall 4 attached. The described oblique course of the ring 32 has the advantage that fuel that may be in 16 left end of the liner 28 drains in through the ring 32 formed channel is forwarded so that it is not on the air supply nozzle 10 drips. So the ring has 32 a very similar function to the guard ring 32 in the embodiment according to 1 ,

But you can also use the ring 32 let it run purely in the axial direction, which is easier in terms of casting technology. Finally, it is possible with an axially extending ring in the freshly cast state 32 to work after inserting the liner 28 against the lining in its free end area 28 is bent. In this case the lining extends 28 at its left end continue towards the central axis 14 the combustion chamber 2 out. The ring 32 then provides a fixation ring for the lining 28 represents.

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

17 shows in schematic form a combustion chamber investment casting 2 , built into a Vehicle heater. In addition to the investment casting, you can see that the circumferential boundary wall 8th the combustion chamber 2 continuing flame tube 58 , part of the housing 80 of the combustion air blower, with the interposition of a seal 82 on the left end face is screwed to the investment casting, a jacket 84 of the heater, a heat exchanger wall 86 , which separates the room 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.

A temperature sensor is located in a recess of the investment cast component from the left, outer end face 90 quite usual training, eg type PT 1000 attached. At the location of the temperature sensor 90 has the blower housing 80 a through hole 92 on. The temperature sensor 90 is by means of a spring clip 94 attached to the blower housing 80 is attached, attached and pressed against the material of the investment casting.

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

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

In order to create a burner for thermal regeneration of an exhaust gas particle filter, the combustion chamber ( 2 ), e.g. the combustion chamber ( 2 ) according to 1 , be inserted into the end of the particle filter housing and completed by a fuel pump and a combustion air blower to the burner. - In the case of a vehicle heating device, a flame tube with a greater axial length than the combustion chamber normally closes, often after an aperture-like cross-sectional narrowing ( 2 ) on. 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, which is heated in this way in the vehicle heater, or air, which is heated in this way to hot air, flows on the outside of the partition wall of the heat exchanger.

Claims (27)

Combustion chamber ( 2 ) a burner for a vehicle heater or for thermal regeneration of an exhaust gas particle filter, which has an end boundary wall ( 4 ), a perimeter boundary wall ( 8th ), a nozzle ( 12 ) to accommodate a glow plug and a nozzle ( 10 ) for supplying combustion air from the front wall ( 4 ) into the combustion chamber ( 2 ) protrudes and at least combustion air exits ( 18 ; 42 ) through the nozzle wall, characterized in that the combustion chamber ( 2 ) with the forehead boundary wall ( 4 ), with the circumferential boundary wall ( 8th ), with the glow plug socket ( 12 ), and with the air supply nozzle ( 10 ) is designed as a one-piece investment casting component. Combustion chamber according to claim 1, characterized in that the glow plug socket ( 12 ) essentially parallel to the longitudinal direction of the combustion chamber ( 2 ) aligned and as a bulge of the circumferential boundary wall ( 8th ) is trained. Combustion chamber according to claim 1 or 2, characterized in that the air supply nozzle ( 10 ) to the inside of the combustion chamber ( 2 ) has an open end and that a flame holder, preferably in the form of a curved plate () downstream of the open end ( 22 ), is arranged. Combustion chamber according to one of claims 1 to 3, characterized in that the investment casting component integrally forms a fastening flange ( 6 ) the combustion chamber ( 2 ), which preferably continues the end wall ( 4 ) lies radially outwards. Combustion chamber according to one of claims 1 to 4, characterized in that up to the downstream end of the air supply nozzle ( 10 ) Longitudinal slots ( 40 ) are provided in the nozzle wall as combustion air outlets. 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 width across the longitudinal direction of the slot ( 42 ) or one via the slot longitudinal direction to the downstream Towards the end, increasing width ( 42 ) Has. 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 with flow component in the circumferential direction of the air supply nozzle ( 10 ) flows out. Combustion chamber according to one of claims 1 to 7, characterized in that the air supply nozzle ( 10 ) tapers in the direction of flow. Combustion chamber according to one of claims 1 to 8, characterized in that it serves as an evaporation combustion chamber on the inside of the end wall ( 4 ) and / or the circumferential boundary wall ( 8th ) a porous lining ( 28 ) to evaporate the fuel. Combustion chamber according to claim 9, characterized in that the lining ( 28 ) consists of sintered metal. Combustion chamber according to claim 10, characterized in that the sintered metal lining ( 28 ) in the unsintered state in the combustion chamber ( 2 ) has been introduced and sintered on the spot. Combustion chamber according to one of Claims 9 to 11, characterized in that the end wall ( 4 ) the combustion chamber ( 2 ) closer end of the lining ( 28 ) and / or that of the forehead boundary wall ( 4 ) the combustion chamber ( 2 ) more distant end of the liner ( 28 ) in an annular gap that is continuous or interrupted in sections ( 56 ; 64 ) is set. Combustion chamber according to claim 12, characterized in that to form the annular gap ( 56 ) a fixing ring that is continuous or interrupted in sections ( 54 ) is provided. Combustion chamber according to claim 13, characterized in that the fixing ring ( 54 ) Is part of the investment casting component. Combustion chamber according to claim 13 or 14, characterized in that the fixing ring ( 54 ) at least at its free end after inserting the lining ( 28 ) on the lining ( 28 ) has been turned. Combustion chamber according to one of claims 12 to 15, characterized in that to form the annular gap ( 64 ) a component ( 66 ; 68 ) is provided, which is connected to the combustion chamber ( 2 ) subsequent flame tube ( 58 ) is attached. Combustion chamber according to one of claims 9 to 16, characterized in that the peripheral boundary wall ( 8th ) the combustion chamber ( 2 ) on the inside a projection extending in the longitudinal direction of the combustion chamber ( 70 ) for the form-fitting determination of the lining ( 28 ) has movement in the circumferential direction. Combustion chamber according to one of claims 9 to 17, characterized in that at the transition between the peripheral boundary wall ( 8th ) the combustion chamber ( 2 ) and the lining ( 28 ) a fuel distribution channel ( 72 ) is provided, which extends over at least part of the circumference of the circumferential boundary wall ( 8th ) extends. Combustion chamber according to claim 18, characterized in that a in the fuel distribution channel ( 72 ) opening fuel supply nozzle ( 74 ) is essentially provided in the circumferential direction for fuel supply. Combustion chamber according to one of claims 9 to 19, characterized in that the porous lining ( 28 ) is coated on the inner surface with copper-containing material for evaporating the fuel or, in the case of a fibrous lining, contains fibers made of copper-containing material or, in the case of a sintered metal lining, contains particles of copper-containing material. Combustion chamber according to one of claims 1 to 20, characterized in that in the flow path of the combustion air in front of the air supply nozzle ( 10 ) An institution ( 50 ) is provided for generating flow swirl. Combustion chamber according to claim 21, characterized in that the device ( 50 ) to generate flow swirl for the most part or all of the investment casting component or part of the housing ( 80 ) one of the combustion chamber ( 2 ) combustion air blower. Combustion chamber according to one of claims 1 to 22, characterized in that between the circumferential boundary wall ( 8th ) and the air supply nozzle ( 10 ) a guide and protection ring ( 32 ) from the forehead boundary wall ( 4 ) from a distance to the inside of the combustion chamber ( 2 ) is arranged projecting. Combustion chamber according to claim 23, characterized in that the downstream end region of the guide and protection ring ( 32 ) is designed to increase turbulence. Combustion chamber according to one of claims 1 to 24, characterized in that radially further outwards than the circumferential boundary wall ( 8th ) the Combustion chamber ( 2 ) a thermal finger ( 98 ) is provided, the end of which in the longitudinal direction of the combustion chamber ( 2 ) lies further forward than its root, and that on the outside of the combustion chamber component in the area where on the inside of the combustion chamber component the root of the heat conducting finger ( 98 ) is a temperature sensor ( 90 ) with which it can be determined whether combustion is taking place or not. Combustion chamber according to claim 25, characterized in that the heat conducting finger ( 98 ) Is part of the investment casting component. Combustion chamber according to one of claims 1 to 26, characterized in that that of the surfaces, which tend to build up carbon-containing deposits in the company, at least a part is copper-containing.