EP2691614B1 - Heating module for an exhaust purification system - Google Patents

Description

The invention relates to a heating module for an exhaust gas purification system connected to the output of an internal combustion engine, comprising a catalytic burner with an HC injector and with a downstream of the HC injector in the flow direction of the exhaust gas oxidation catalyst for supplying thermal energy to an exhaust gas purification unit of the emission control system, said Heating module has a main line, a secondary line containing the catalytic burner and a device for controlling the exhaust gas mass flowing through the secondary line, wherein the secondary line has on the input side and on the output side via a deflecting in the radial direction from the main strand, between which deflection chambers parallel to Main strand of the heating module is the Nebenstrangabschnitt with the oxidation catalyst.

Internal combustion engines, currently especially diesel engines, have units connected to the exhaust line to reduce harmful or undesirable emissions. Such an aggregate may be, for example, an oxidation catalytic converter, a particulate filter and / or an SCR stage. A particulate filter serves to catch soot particles ejected from the internal combustion engine. On the upstream surface of the particulate filter accumulates in the exhaust soot accumulates. So that in the course of successive Rußakkumulation the exhaust back pressure does not rise too far and / or the filter threatens to clog, a sufficient regeneration process is triggered with sufficient soot loading of the particulate filter. In such a regeneration process, the soot accumulated on the filter is burned off (oxidized). Upon completion of such soot oxidation, the particulate filter is regenerated. All that remains is a non-combustible ashes. For soot oxidation to take place, the soot must have a certain temperature. This is usually around 600 degrees Celsius. The temperature at which such soot oxidation begins may be lower, for example when the oxidation temperature has been lowered by an additive and / or by the provision of NO ₂ . If the carbon black has a temperature which is below its oxidation temperature, it is necessary to supply thermal energy for triggering the regeneration process in order to be able to actively trigger a regeneration in this way. Active regeneration may be initiated via engine-internal measures by changing the combustion process to expel exhaust gas at a higher temperature. However, in many applications, especially in the non-road area, post-motor actions are preferred for inducing active regeneration. In many cases, it is not possible to influence engine measures as part of an exhaust gas purification.

Out DE 20 2009 005 251 U1 For example, an exhaust emission control system is known in which, for the purposes of actively causing the regeneration of a particulate filter, the exhaust gas line is divided into a main line and a secondary line. These two strand sections form a heating module. In the secondary line, a catalytic burner is turned on, heated by the flowing through the side branch partial exhaust stream and then combined with the flowing through the main strand exhaust stream, so that in this way the mixed exhaust gas mass flow has a much higher temperature. The purpose of increasing the temperature of the exhaust gas stream is to heat the soot accumulated on the upstream side of the particulate filter to a sufficient temperature for triggering the regeneration process. As a catalytic burner is arranged in the secondary strand oxidation catalyst with upstream hydrocarbon injection. For controlling the exhaust gas mass flow flowing through the secondary line, there is an exhaust gas flap in the main line, by means of which the freely flow-through cross-sectional area in the main line can be adjusted. For the purpose of heating the oxidation catalyst switched on in the secondary strand to its light-off temperature-the temperature at which the desired exothermic HC conversion takes place at the catalytic surface-this is preceded by an electrothermal heating element. This is operated when this oxidation catalyst must be heated to its light-off temperature. It is also described in this document that the catalytic burner connected in the secondary line can be oversprayed so as to supply hydrocarbons to a second oxidation catalyst immediately upstream of the particle filter in order to produce the same exothermic reaction on the catalytic surface of this second oxidation catalyst can react. Thus, in this prior art emission control system, a two-stage heating of the exhaust gas can be made. The exhaust gas flowing out of the second oxidation catalytic converter then has the necessary temperature in order to heat the soot accumulated on the upstream side of the particulate filter to such an extent that it oxidizes.

Similarly, it may be desirable to increase the temperature of other emission control units, such as an oxidation catalyst or SCR stage, to bring them to their operating temperature more quickly.

US 2011/061369 A1 discloses a burner for a diesel engine downstream exhaust gas purification system. In this exhaust gas purification system, the exhaust gas flow in the region of the input is divided into a main line and a secondary line. Both strands are arranged concentrically to each other.

The object of the invention is to develop a heating module of the type mentioned in such a way that this not only compact design designed, but with which the oxidation catalyst can be heated more effectively.

This object is achieved according to the invention by a heating module having the features of claim 1.

In this heating module, the branch into the secondary line and, according to one embodiment, the mouth of the secondary line in the main line are typically each formed by an overflow pipe section. Such an overflow pipe section has overflow openings, which are introduced into the pipe forming the overflow pipe section. Thus occurs over the input side arranged with respect to the Nebenstranges Überströmrohrabschnitt, which is located in the region of the input of the heating mode, in the radial direction of the exhaust duct to be guided through the secondary strand in the radial direction from the main strand and in the secondary strand when the exhaust gas flow through or part to be routed to the secondary strand. The conception of the formation of the input in the secondary line using such Overflow pipe sections allow the formation of a direction of the main flow direction of the exhaust gas also arranged at right angles branch as part of the secondary strand. The output-side connection of the secondary line to the main line can be designed in the same way. According to a further embodiment, it is provided that the main line and the secondary line open into a mixing chamber in the axial direction and thus in the main flow direction of the exhaust gas. In these designs, the longitudinal extent of the secondary strand with the catalytic burner can be limited essentially to the necessary length of the oxidation catalyst. If the catalytic burner is also assigned an electrothermal heating element upstream of the oxidation catalytic converter in the flow direction, the length of the secondary line can be practically limited to the required length of the oxidation catalytic converter and of the heating element arranged upstream of it. The above-described concept involves that the secondary branch branched off from the main branch at a right angle has a 90 degree deflection in order to guide the exhaust gas stream into a secondary strand section running parallel to the main strand. The related diversion is typically in the region of the longitudinal axis of the secondary section with the oxidation catalyst, so that it is advisable to arrange the HC injector in the region of the deflection, in such a way that its spray cone frontally on the oxidation catalyst or, if this upstream of an electrothermal heating element is directed to this. Thus, no additional space in the longitudinal extension of the heating module is required for the necessary flow path for forming the spray cone of the HC injector. In order to form the spray cone, the depth of the existing deflection, which is required anyway, is used in this design.

Particularly advantageous is an embodiment in which the heating module has an upstream of the oxidation catalyst electrothermal heating element, since this can be used to vaporize the introduced via the HC injector in the secondary strand fuel before it acts on the catalytic surface of the oxidation catalyst. Consequently, in such an embodiment, only a minimum of flow path between the HC injector or its injector nozzle and the oxidation catalyst needs to be present. It serves the necessary Flow path not as a treatment line, but most of the purpose of Sprühkegelausbildung so that the entire or largely entire upstream surface of the heating element is in the range of the spray cone. In this case, the spray cone will typically be adjusted such that it preferably acts only on the upstream surface of the heating element and not or at most only subordinate in the flow direction upstream wall sections of the secondary strand section.

The conception of the input-side main branch branch through an overflow pipe section which, depending on the configuration of the heating module, encloses the secondary line or which is enclosed by the outgoing secondary line, permits the formation of numerous overflow openings, which are preferably distributed uniformly over the circumference of the overflow pipe section. The configuration of the overflow openings and their arrangement will preferably be chosen such that, if possible, an equal distribution of the exhaust gas stream flowing into the secondary line is provided in the secondary line. The aim is to uniformly flow the oxidation catalyst arranged in the secondary branch or, if present, the electrothermal heating element arranged upstream of it via the cross-sectional area of the secondary strand. In principle, a conception is possible in which the overflow openings extend over only a part of the lateral surface of the overflow pipe section, for example only over 180 degrees. Regardless of the above-described design of the overflow pipe section, it is considered appropriate if the cross-sectional area of the overflow openings in their sum is slightly larger than the cross-sectional area of the main strand in the region of the overflow pipe section. As a result, the exhaust backpressure occurring through the necessary internals in the secondary line can be kept low. According to one exemplary embodiment, it is provided that the sum of the cross-sectional areas of the overflow openings of the overflow pipe sections is 1.2 to 1.5 times greater than the cross-sectional area of the main strand in the overflow pipe section. It has been found that a related cross-sectional area ratio of about 1.3 proves to be particularly favorable in order not to adversely affect the flow behavior through the two strands - main line and secondary line - beyond measure.

The concept of connecting the secondary line over overflow pipe sections as described above, to the main strand allows formation of the overflow pipe sections and thus the branches by appropriate dimensioning of the overflow, in terms of their number and diameter, that the guided through the main strand exhaust stream when flowing through the main strand of the Heizmodules at the branches only a minimal and thus negligible exhaust gas back pressure learns.

The Überströmrohrabschnitt limits the main strand depending on the design of the heating module on the outside or inside. In the first embodiment, the exhaust gas flow to be conducted through the secondary line is directed in the radial direction outwards from the main line into the secondary line. The oxidation catalyst and, if appropriate, the heating element arranged upstream of this are then located in a pipe arranged parallel to the main strand as a secondary strand section.
The return of the exhaust gas flow conducted through the secondary line into the main flow can take place in an analogous manner as at the inlet of the secondary line via a overflow pipe section having a second overflow opening. The above comments on the input-side overflow pipe section equally apply in such a configuration also for the overflow pipe section arranged on the output side with regard to the secondary strand. The introduction of the exhaust stream flowing out of the secondary branch into the main branch or into the exhaust gas stream flowing through it ensures a particularly effective mixing of the two partial exhaust streams merged at this point over a very short distance. This means that even after a very short flow path of the exhaust gas behind the outlet-side overflow pipe section, the exhaust gas mixed stream has a very uniform temperature distribution with respect to its cross-sectional area.

The fluid connection between the main strand and the secondary strand section with the oxidation catalyst, and preferably also with the electrothermal heating element connected upstream thereof, is realized by overflow deflection chambers in an embodiment in which the secondary strand section with the catalytic burner runs parallel to the main strand. These summarize the main strand, each with a Überströmrohrabschnitt. At a distance from the main line is to the Überströmumlenkkammern the Nebenstrangabschnitt connected with its internals. The Überströmumlenkkammern are part of the Nebenstranges. Such a configuration allows the design of a secondary section with its internals, whose diameter is significantly larger than the diameter of the main strand. Accordingly, in such a secondary strand section a correspondingly large diameter oxidation catalyst can be turned on. It is understood that, the larger the cross-sectional area of the oxidation catalyst, it can be designed shorter at the same volume in its longitudinal extent. As a result, not only the possibility is created to design the heating module in the longitudinal extension correspondingly shorter, but by such a measure, the back pressure and the conversion rate and thus the temperature load of the oxidation catalyst can be reduced.

In principle, the same advantages, with the exception of those mentioned to the overflow pipe sections, in a heating module, in which the secondary line on the input side and output side each has a radially outgoing from the main strand deflection, between which deflection parallel to the main strand of the heating module of the secondary strand section the oxidation catalyst is located. Therefore, such an embodiment represents a further solution of the problem underlying the invention.

The concept of forming the fluid connections between the secondary strand section with the oxidation catalyst and the preferably upstream electrothermal heating element with the main strand by means of the above deflection chambers allows a design thereof as Blechumformteile, typically two such, usually formed by deep drawing sheet metal parts are assembled into a deflection chamber. This concept allows the use of identical parts in the input-side deflection chamber and in the output-side deflection chamber, at least with respect to a prefabrication stage. In fact, the Umlenkkammerteile by introduced after this prefabrication level openings for connecting such as sensors or, for example, an HC injector from each other. In principle, the outer Umlenkkammerteile can be the same. Alone with the input side outside Umlenkkammerteil are typically provided connecting means for connecting the HC injector. According to one embodiment, this deflection chamber part has an injector opening with an outwardly flanged collar to which the HC injector is attached. Also, this Umlenkkammerteil can be made as a common part to the outer Umlenkkammerteil the other deflection, wherein the HC injector has been introduced by an additional processing step in this initially manufactured as a common part Umlenkkammerteil.

Fig. 1:

Eine schematisierte An- bzw. Einsicht in ein Heizmodul gemäß einem ersten Ausführungsbeispiel zum Zuführen von thermischer Energie in den Abgasstrang einer an den Ausgang einer Brennkraftmaschine angeschlossenen Abgasreinigungsanlage,

Fig. 2:

Eine erste Stirnseitenansicht (Seitenansicht von links) auf das Heizmodul der Figur 1,

Fig. 3:

Eine weitere Stirnseitenansicht (Seitenansicht von rechts) auf die der Seitenansicht der Figur 2 gegenüberliegende Seite des Heizmoduls der Figur 1,

Fig. 4:

Eine Darstellung entsprechend derjenigen der Figur 1 mit darin eingezeichneten Strömungspfeilen bei einem Betrieb des Heizmoduls,

Fig. 5:

Eine perspektivische An- bzw. Einsicht in ein Heizmodul gemäß einem nicht erfindungsgemäßen Ausführungsbeispiel zum Zuführen von thermischer Energie in den Abgasstrang einer an den Ausgang einer Brennkraftmaschine angeschlossenen Abgasreinigungsanlage,

Fig. 6:

Eine schematisierte An- bzw. Einsicht in das Heizmodul der Figur 5 mit darin eingezeichneten Strömungspfeilen bei einem Betrieb des Heizmodules und

Fig. 7a, 7b:

Eine Querschnittsdarstellung des Heizmoduls der Figuren 5 und 6 (Figur 7a) sowie einen Ausschnitt eines Längsschnittes des genannten Heizmodules (Figur 7b) im Bereich der Anordnung einer Abgasklappe.

Further advantages and advantageous embodiments of the invention will become apparent from the following description of an embodiment with reference to the accompanying figures. Show it:

Fig. 1:

A schematic view or insight into a heating module according to a first embodiment for supplying thermal energy in the exhaust line of an exhaust gas purification system connected to the output of an internal combustion engine,

Fig. 2:

A first end view (side view from the left) on the heating module of FIG. 1 .

3:

Another front view (side view from the right) on the side view of the FIG. 2 opposite side of the heating module of FIG. 1 .

4:

A representation corresponding to that of FIG. 1 with flow arrows drawn in during operation of the heating module,

Fig. 5:

A perspective view or insight into a heating module according to a non-inventive embodiment for supplying thermal energy in the exhaust line of an exhaust gas purification system connected to the output of an internal combustion engine,

Fig. 6:

A schematic view or insight into the heating module of FIG. 5 with therein flow arrows during operation of the heating module and

Fig. 7a, 7b:

A cross-sectional view of the heating module of Figures 5 and 6 ( Figure 7a ) and a section of a longitudinal section of said heating module ( FIG. 7b ) in the region of the arrangement of an exhaust flap.

A heating module 1 of a first embodiment of the invention is turned on in an exhaust line, not shown, an exhaust gas purification system. The emission control system is in turn connected to the output of a diesel engine as an internal combustion engine. The exhaust gas line, in which the heating module 1 is turned on, is identified by the reference symbol A. The heater 1 is in the flow direction of the exhaust gas, through the block arrows in FIG. 1 shown upstream of an exhaust gas purification unit, for example, a particulate filter in the flow direction of the exhaust gas. Preferably, the particle filter is preceded by an oxidation catalyst.

The heating module 1 according to a first embodiment of the invention has a main line 2 and a secondary line 3. The main line 2 is part of the exhaust line A of the exhaust gas purification system. Through the main branch 2 of the heating module 1, the exhaust gas emitted by the diesel engine flows when it is not passed through the secondary line 3. If the heating module 1 for supplying thermal energy into the exhaust gas line in operation, the exhaust gas flow is wholly or partially passed through the secondary strand 3. For controlling the exhaust gas flow through the main line 2 and / or the secondary line 3, an exhaust flap 5 which can be controlled by an actuator 4 is arranged in the main line 2. In FIG. 1 the exhaust flap 5 is shown in its closing the main strand 2 position. Depending on the position of the exhaust flap 5 within the main line 2, the entire exhaust gas flow through the main strand 2 or through the secondary strand 3 or a partial flow through the main strand 2 and the complementary partial flow through the secondary strand 3 are passed.

The main strand 2 of the heating module 1 has on the input side and output side with respect to the secondary strand 3 each have a Überströmrohrabschnitt 6, 6.1. The overflow pipe section 6 of the illustrated embodiment is realized by a perforation, which is formed by a plurality of these pipe section cross-overflow openings 7. In the illustrated embodiment, the overflow 7 have a circular cross-sectional geometry and are circumferentially distributed in a uniform grid and designed with the same cross-sectional area. It is understood that both the arrangement of the overflow openings 7, their cross-sectional geometry and their size vary and may also be provided differently arranged over the Überströmrohrabschnitt typically in the flow direction of the exhaust gas. In the illustrated embodiment, the sum of the cross-sectional area of the overflow openings 7 is about 1.3 times as large as the cross-sectional area of the main string 2, typically in the region of the overflow pipe section 6. The overflow pipe section 6.1 with respect to the secondary strand 3 is designed identically. However, the conception of the output-side overflow pipe section 6.1 can also be designed differently than the input-side overflow pipe section 6.

The overflow pipe section 6 is bordered by an overflow deflection chamber 8. The enclosure of the overflow pipe section 6 is circumferentially, since in the illustrated embodiment, the overflow 7 distribute circumferentially over the overflow pipe section 6. As a result, all the overflow openings 7 of the overflow pipe section 6 are located within the overflow deflection chamber 8. Through this measure, exhaust gas can flow out of the main branch 2 into the auxiliary line 3 over the entire circumference of the overflow pipe section 6. The Überströmumlenkkammer 8 is composed of two formed by deep drawing sheet metal parts - the Umlenkkammerteil 9, 9.1 - composed. At the mutually facing sides of Umlenkkammerteile 9, 9.1 each have a mounting flange 10, 10.1, with which the two Umlenkkammerteile 9, 9.1 are gas-tightly connected to each other by a joining process. The overflow pipe section 6.1 is bordered in the same way by a Überströmumlenkkammer 8.1.

Parallel and at a distance from the main strand 2 extends between the two mutually facing deflection chamber parts 9, 9.1 of the overflow deflection chambers 8, 8.1, a secondary strand section 11, which in the illustrated embodiment is designed as a tube with a circular cross-sectional geometry. In the secondary line section 11 is an oxidation catalyst 12 and upstream of this in the flow direction an electrothermal heating element 13. The necessary connections for operating the heating element 13 are not shown in the figures for the sake of clarity. To the outer Umlenkkammerteil 9 Überströmumlenkkammer 8 HC injector 14 is connected. The HC injector 14 is used for spraying fuel (here: diesel), so as to allow hydrocarbons to operate the catalytic burner formed together with the oxidation catalyst 12. The HC injector 14 is connected in a manner not shown to the fuel supply, from which also the diesel engine is fed.

The above-described shell construction of Überströmumlenkkammern 8, 8.1 allows that they can be made of identical parts. For connecting the HC injector 14, an injector opening is introduced into the deflecting chamber part 9 and an opening for accommodating a temperature sensor connection in the deflecting chamber part 9.1 of the other overflow deflecting chamber 8 in the embodiment shown. This is located in alignment with the longitudinal axis of the secondary strand section eleventh

The side views of FIGS. 2 and 3 of the heating module 1 show that the Überströmumlenkkammern 8, 8.1, starting from the main strand 2 in the direction of the secondary strand section 11 in terms of flow cross-sectional area increase. On the input side, this increase in cross-sectional area results in a slowing down of the exhaust gas flow conducted through the secondary branch 3. This is desirable so that the spray cone formed by the HC injector 14 is largely uninfluenced by the inflowing exhaust gas flow when injecting fuel. The fuel cone sprayed by the HC injector 14 is designed so that it wets the upstream end of the heating element 13 with fuel, wherein the spray cone does not have such an angle that in the flow direction before the heating element 13 located wall portions of the secondary strand section 11 are wetted with fuel. The cross-sectional area of the secondary strand section 11 is, as shown in FIGS FIGS. 1 to 3 recognizable, again slightly smaller than the flow cross-sectional area within the Überströmumlenkkammer 8 (the same applies to the Überströmumlenkkammer 8.1) in the region of in the Figures 2 The consequence is that enters into the secondary strand section 11 into a certain acceleration of the introduced into the secondary branch 3 exhaust gas flow, whereby possible spray-off of the HC injector 14 is drawn into the secondary strand section 11 and the electrothermal Heating element 13 is supplied, therefore unwanted wall deposits can be avoided.

In the side view of the heating module 1 of FIGS. 2 and 3 is the exhaust valve 5 in its opposite the representations of FIG. 1 rotated by 90 degrees position. This is due to the fact that the exhaust gas flow acting on the heating module 1 is counteracted by the secondary line 3 by a slightly larger exhaust counterpressure than this by the main branch 2 and the heating module 1 downstream Components of the emission control system 1 is the case.

In the illustrated embodiment, the cross-sectional area in the secondary strand section 11 is slightly more than twice the cross-sectional area of the main strand 2. This takes place against the background that for forming a heat module 1 that is as compact as possible, especially the cross-sectional area of the internals-heating element 13 and oxidation catalyst 12 - Can be used and especially the oxidation catalyst 12 must have only a relatively short extent in the flow direction of the exhaust gas. It has been shown that, especially in the longitudinal extent of an exhaust line, the installation space is often limited, while in the transverse direction, there are sometimes opportunities for accommodating certain units. This requirement is sufficient because of the above-described concept, the heating module 1 in particular.

The Überströmumlenkkammer 8.1 carries a temperature sensor 15, with the exhaust gas temperature on the output side with respect to the oxidation catalyst 12 can be detected.

From the representation of FIGS. 1 to 3 It is also clear that the Actuator 4 not, as shown in the figures, must be arranged on the underside of the representation of the figures of the heating module 1, but the actuator 4 can be arranged rotated both in the one and in the other direction about the longitudinal axis of the main strand 2, depending after, at which point in a particular application the required space is available.

Hereinafter, the operation of the heating module 1 will be briefly described. Operates the heating module 1 for supplying thermal energy in the exhaust stream of the diesel engine, for example, to trigger a regeneration of a downstream in the emission control system with respect to the heating module 1 particulate filter and optionally control. If the exhaust gas emitted by the diesel engine has exceeded a certain temperature, before the actual operation of the heating module 1, a part of the exhaust gas flow or even the entire exhaust gas flow is passed through the secondary strand 3. This serves the purpose of preheating the oxidation catalyst 12, as far as possible by the temperature of the exhaust gas stream, and to bring this, if the temperature of the exhaust gas is sufficiently high, to its operating temperature. Can not be brought to its light-off temperature by this measure, the oxidation catalyst 12, in addition, the electrothermal heating element 13 is energized so that the oxidation catalyst is heated by the heated by the heating element 13 exhaust stream.

If the heating module 1 is the first part of a two-stage catalytic burner arrangement, it will be preferable to design the oxidation catalyst 12 with a higher oxidation-catalytic loading than the oxidation catalyst arranged downstream of it in the main line. Consequently, in such an embodiment, the light-off temperature of this oxidation catalyst 12 is lower.

For the actual operation of the heating module 1, either the entire, the heating module 1 acting on the exhaust stream or only part thereof is passed through the secondary strand 3, depending on the temperature to be performed. Accordingly, the exhaust valve 5 is set in the main line by means of the actuator 4. It is understood, when the exhaust valve 5 is in the main line in its closed position, the majority of the exhaust gas flow passed through the secondary line 3 becomes. Conversely: If the exhaust flap is in its fully open position, as in the side view of FIG. 2 Recognizable, the entire exhaust gas flow flows through the main strand 2 of the heating module 1. In an operation of the heating module 1, the flowing through the secondary strand 3 exhaust gas flow through the operation of the switched therein catalytic burner, formed in the illustrated embodiment by the HC injector 14, the Heating element 13 and the oxidation catalyst 12, heated. For this purpose, the electrical heating element 13 is energized, so that evaporates at this injected via the HC injector 14 fuel. The spray cone S of the HC injector 14 is in FIG. 4 schematized drawn. The fuel vaporized on the heating element 13 acts on the catalytic surface of the oxidation catalyst 12 and triggers the desired exothermic reaction. The exhaust gas stream heated in this way by the secondary branch 3 is returned to the main branch 2 via the overflow deflecting chamber 8.1, whereby a particularly effective mixing takes place as the hot exhaust gas flow passes through the overflow openings 7 into the significantly cooler exhaust gas substream flowing through the main branch 2 over a short distance.

It is understood that fuel is injected into the secondary line 3 by the HC injector 14 only when the oxidation catalytic converter 12 is above its light-off temperature.

FIG. 5 shows a further heating module 1.1 according to a non-inventive embodiment. The heating module 1.1 is basically constructed as the heating module 1 of FIGS. 1 to 4 , Therefore, the comments on the heating module 1 also apply to the heating module 1.1, unless otherwise explained below.

In the case of the heating module 1.1, the secondary line section 11.1 with the oxidation catalytic converter 12.1 and the heating element 13.1 upstream of this is arranged within the main line 2.1. In this conception and the illustrated embodiment of the heating module 1.1 are main strand 2.1 and side branch 3.1 in a concentric arrangement to each other. The exhaust line A opens in the illustrated embodiment radially into the main line 2.1. The main strand 2.1 is due to the concentric arrangement in the radial direction inside bounded by the minor strand 3.1. In the area of the entrance of the heating module 1.1, an overflow pipe section 6.2 is connected upstream of the secondary line section 11.1. The overflow pipe section 6.2 is formed as well as the overflow pipe sections 6, 6.1 of the embodiment of the FIGS. 1 to 4 , Therefore, the relevant explanations also apply to the overflow pipe section 6.2 of the heating module 1.1. The overflow openings 7.1 are circumferentially introduced into the overflow pipe section 6.2 and have in the illustrated embodiment, a circular cross-sectional geometry. Thus, the overflow pipe section 6.2 or its overflow openings 7.1 forms the inlet and thus the flow connection between the main strand 2.1 and the secondary strand 3.1. In contrast to the heating module 1 occurs in the heating module 1.1 of the exhaust stream to be passed through the secondary strand 3.1, in the radial direction on the inside and thus from the inner surface of the main strand 2.1 and in the secondary strand 3.1 a. An HC injector 14.1 is arranged in an axial arrangement with respect to its injection nozzle to the secondary line 3.1, so as well as the HC injector 14 of the heating module 1. The inlet opening for the influx of exhaust gas into the main strand may alternatively also tangentially or axially with respect to Main flow direction of the exhaust gas to be performed by the heating module 1.1. If an axial input opening, this may, if desired, be annular.

Even with the heating module 1.1, the electrical connections for the heating element 13.1 are not shown for the sake of clarity.

The main strand 2.1 thus surrounds the secondary strand 3.1 and thus forms an annular chamber. In this annular chamber, a helix 16 is used as a guide element through which the flowing in the radial direction in the main line 2.1 exhaust gas undergoes a rotational movement component. Consequently, the exhaust stream flowing through the main branch 2.1 is set into a rotational movement by this embodiment. Through the helix 16, which extends over the entire height of the annular chamber, a helically extending around the secondary strand 3.1 flow channel is formed at the same time. This channel is used in the illustrated embodiment, to arrange an exhaust valve 5.1 therein. This is, as well as in the embodiment of FIGS. 1 to 4 , driven by an actuator 4.1. The exhaust flap 5.1 is pivotable about a radially extending to the longitudinal axis of the secondary strand 3.1 axis of rotation. In FIG. 5 the exhaust valve 5.1 is shown in its open position. Due to the formation of the flow channel created by the helix 16, which ultimately constitutes the fluidically effective part of the main branch 2.1, the exhaust gas stream conducted through the main branch 2.1 is conducted around the lateral surface of the secondary strand 3.1. This longer throughflow path has the advantage that, depending on the operating state, the temperature of the inflowing exhaust gas heats the oxidation catalyst 12.1 arranged in the auxiliary section 3.1, and therefore typically at least approximately has the temperature of the exhaust gas. Therefore, it is in principle not necessary in this embodiment for preheating the oxidation catalyst 12.1 prior to operation of the catalytic burner to direct the exhaust gas stream or a part thereof through the secondary strand 3.1. If the catalytic burner is in operation, the heat emitted by the secondary branch section 11.1 is not transferred to the environment but to the partial exhaust gas stream flowing through the main branch 2.1. It is understood that for the purpose of heating the oxidation catalyst 12.1 on the one hand or flowing through the main strand 2.1 partial exhaust gas flow on the other hand, the longer flow path of the main strand as a result of the spiral 16 formed by the flow chamber ensures a particularly effective heat transfer.

FIG. 6 shows a representation in an operation of the heating module 1.1, which in principle the representation of FIG. 4 corresponds to the heating module 1. Entered in these are in a schematic on or insight flow arrows. The exhaust gas flow flowing through the overflow openings 7.1 of the overflow pipe section 6.2 into the secondary line 3.1 is indicated by the arrows with dashed border, since the relevant exhaust gas flow lies within the secondary line 3.1. The exhaust valve 5.1 is located to increase the exhaust backpressure in the main strand 2.1 in their opposite to the representation in FIG. 5 rotated by 90 degrees position. In this position, the exhaust valve 5.1 does not completely close the flow channel, as follows FIGS. 7a, 7b explained, so that a small proportion of exhaust gas flow through the main strand 2.1 flows. The rotation of this partial exhaust stream to the secondary strand 3.1 is shown schematically by arrows.

From the cross-sectional view of Figure 7a by the heating module 1.1 in the same longitudinal extent just before the exhaust valve 5.1, the geometry of the exhaust valve 5.1 in its open position (see also FIG. 5 ) clear. The rotational flow of the exhaust stream through the main strand 2.1 is indicated by block arrows. Also clearly visible is the concentric arrangement of the secondary strand section 11.1 with the arranged in the sectional plane of the oxidation catalyst 12.1 to the main strand 2.1. The exhaust flap 5.1 has in the radial direction to the outside a curved end 18, which is adapted to the curvature of the main strand 2.1 enclosing housing. If, on the other hand, the exhaust flap 5.1 is in its closed position, as shown in FIG. 7b, it becomes clear that due to the closure 18 in this position, the main branch 2.1 can not be completely closed by the exhaust flap 4.1, as described above, so that in this position at the exhaust flap 5.1 a certain partial exhaust gas stream flows past the main strand 2.1.

At the output of the secondary string 3.1 is a perforated plate, not shown in the figures. Both the main strand 2.1 and the secondary strand 3.1 open into a conically tapering mixing chamber 17. In this passes the guided through the main strand 2.1 partial exhaust gas stream as a rotating ring flow, which encloses the opening into the mixing chamber 17, flowing through the secondary line 3.1 exhaust stream. The constriction formed by the tapering of the mixing chamber 17 and the swirl of the exhaust gas stream flowing through the main branch 2.1 into it require a particularly effective mixing of the two exhaust gas substreams over a very short distance. When merging the two partial exhaust gas streams, the partial exhaust gas stream flowing out of the secondary branch 3.1 can likewise enter the mixing chamber 17 by providing a corresponding orifice as concentric annular flow to the partial exhaust gas stream leaving the main branch 2.1. If one or more guide elements are additionally provided in such an embodiment, the partial exhaust gas stream leaving the secondary branch 3.1 can also flow into the mixing chamber 17 as a swirl flow, the swirl of the partial exhaust gas stream leaving the secondary branch 3.1 being opposite to the swirl of the secondary exhaust flow for the purposes of intensive mixing is directed through the main strand 2.1 flowing exhaust gas partial stream. It is also possible that the exhaust gas streams through each other by appropriate guide elements to have directed radial flow components when flowing into the mixing chamber 17.
Is schematized in FIG. 6 also the spray cone S of the HC injector 14.1 shown. Due to the radial inflow of the exhaust gas out of the main branch 2.1 through the overflow openings 7.1 into the secondary branch 3.1, spray-off deposits of the HC injector 14.1 on the inside of the overflow pipe section 6.2 and the adjacent secondary section 11.1 are effectively avoided.

The heating module 1.1 underlying concept not only ensures a temperature-efficient design of the heating module but also a particularly space-saving design.
In the in the Figures 5 and 6 In the embodiment shown, the mixing chamber 17 adjoining the outlets of the two strands 2.1, 3.1 is conically tapered in the main flow direction of the exhaust gas. Such a rejuvenation is basically not required. Rather, the mixing chamber can also be cylindrical, to which cylindrical portion, after a short flow path, that exhaust gas purification unit can already connect to which the temperature provided by the heating module 1.1 is to be supplied.

LIST OF REFERENCE NUMBERS

1, 1.1

heating module

2,2.1

main line

3,3.1

secondary line

4,4.1

actuator

5,5.1

exhaust flap

6,6.1,6.2

Überströmrohrabschnitt

7,7.1

overflow

8,8.1

Überströmumlenkkammer

9,9.1

Umlenkkammerteil

10, 10.1

mounting flange

11, 11.1

Secondary line section

12, 12.1

oxidation catalyst

13, 13.1

heating element

14, 14.1

HC injector

15

temperature sensor

16

spiral

17

mixing chamber

18

graduation

A

exhaust gas line

S

spray cones

Claims (8)

1. Heating module for an exhaust gas purification system connected to the outlet of an internal combustion engine, comprising a catalytic burner with an HC injector (14) and with an oxidation catalytic converter (12) positioned downstream of the HC injector (14) in the flow direction of the exhaust gas, for supplying thermal energy to an exhaust gas purification unit of the exhaust gas purification system, wherein the heating module (1) has a main section (2), a secondary section (3) which comprises the catalytic burner (12, 14), and a device (4, 5) for controlling the exhaust gas mass flow flowing through the secondary section, wherein the secondary section (3) has, on the input side and output side in each case, a diverting chamber (8, 8.1) departing from the main section (2) in the radial direction, between which diverting chambers (8, 8.1) is situated, parallel to the main section (2) of the heating module (1), the secondary section portion (11) with the oxidation catalytic converter (12), characterised in that the transverse cross-section of the input-side diverting chamber (8) expands in the direction of flow of the exhaust gas, the cross-section surface of the output side diverting chamber (8.1) tapers in the direction of flow of the exhaust gas, and the secondary section portion (11) with the oxidation catalytic converter (12) is arranged between the sections of the diverting chambers (8, 8.1) which are larger in relation to their cross-section surfaces.
2. Heating module according to claim 1, characterised in that the cross-section surface of the secondary section portion (11) with the oxidation catalytic (12) converted extending between the diverting chambers (8, 8.1) is more than twice as large as the cross-section surface in the main section (2).
3. Heating module according to claim 1 or 2, characterised in that the diverting chambers (8, 8.1) are composed in each case of two sheet-metal shaped sections joined to one another.
4. Heating module according to claim 3, characterised in that the diverting chambers (8, 8.1) comprise parts which, at least in a pre-production stage, are identical in relation to these parts forming the diverting chambers, such as identical part to the diverting chamber parts (9.1) facing one another in the heating module (1).
5. Heating module according to claim 3 or 4, characterised in that the external diverting chamber part (9) of the inlet-side diverting chamber (8) comprises an HC injector opening with a collar which is flanged to the outside, in order to connect the HC injector (14).
6. Heating module according to any one of claims 1 to 5, characterised in that the HC injector (14) is arranged with its atomizer nozzle in the alignment of the longitudinal axis of the secondary section portion (11) containing the oxidation catalytic converter (12).
7. Heating module according to any one of claims 1 to 6, characterised in that an electro-thermal heating element (13) is inserted in the secondary section (3) downstream of the HC injector (14) in the flow direction of the exhaust gas, and upstream of the oxidation catalytic converter (12).
8. Heating module according to any one of claims 1 to 7, characterised in that the device (4, 5) for controlling the exhaust gas mass flow flowing through the secondary section (3) is arranged in the main section (2) of the heating module (1).

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