MIXER ARRANGEMENT AND METHOD FOR OPERATING A MIXER ARRANGEMENT

Abstract

A mixer arrangement for an exhaust gas system, having an inlet opening through which an exhaust gas mass flow (A) can be guided, and a mixer for swirling the exhaust gas, which has at least one inflow opening that is fluidically connected to the inlet opening, wherein at least one first portion (A1) of the exhaust gas mass flow (A) can be guided through the mixer via the at least one inflow opening, an injection device by means of which an additive can be injected, and a bypass having at least one throughflow opening which is fluidically connected to the inlet opening and through which a second portion (A2) of the exhaust gas mass flow (A) can be guided past the mixer, there being provided at least one regulating body by means of which a flow cross-section Q in the mixer arrangement can be varied such that a ratio V with (formula I) can be varied.

Claims

1. A mixer arrangement for an exhaust gas system, having an inlet opening through which an exhaust gas mass flow A can be guided into the mixer arrangement, a mixer for swirling the exhaust gas, which has at least one inflow opening that is fluidically connected to the inlet opening, wherein at least one first portion A1 of the exhaust gas mass flow A can be guided through the mixer via the at least one inflow opening, wherein the mixer has guide plates in order to swirl the exhaust gas, an injection device by means of which an additive can be injected, and a bypass having at least one throughflow opening which is fluidically connected to the inlet opening and through which a second portion A2 of the exhaust gas mass flow A can be guided past the mixer, wherein at least one regulating body is provided, by means of which a flow cross-section Q in the mixer arrangement can be varied so that a ratio $V\mathrm{with}=\frac{A2}{V1}$ can be varied, wherein the mixer lies with an overlapping region within a bypass channel of the bypass, wherein the bypass channel completely surrounds a mixer wall of the mixer in such a way that the hot exhaust gas of the second portion A2 heats the mixer wall.

2. The mixer arrangement according to claim 1, wherein the injection device is placed on the mixer, wherein an additive can be injected into an injection section of the mixer by means of the injection device.

3. The mixer arrangement according to claim 1, wherein the regulating body has an actuator by means of which the ratio V can be varied so that a variance range ΔA1 of the first portion A1 of the exhaust gas mass flow A is minimized depending on at least one engine parameter.

4. The mixer arrangement according to claim 1, wherein an electronic control unit is provided, which is coupled to the regulating body and which regulates an actuator of the regulating body depending on at least one engine parameter.

5. The mixer arrangement according to claim 1, wherein the regulating apparatus can be brought into a first position P1 and a second position P2, wherein the second portion A2 of the exhaust gas mass flow A through the bypass in the first position P1 of the regulating body is at most 30%, 20%, 10% or 0% with respect to the second portion A2 of the exhaust gas mass flow A in a second position P2 of the regulating body.

6. The mixer arrangement according to claim 1, wherein the mixer has a mixer wall which has a tubular configuration, wherein multiple inflow openings are provided, wherein at least one blade is provided, which is set at an angle α with respect to an inflow opening so that a swirl movement of the exhaust gas can be generated in the injection section.

7. The mixer arrangement according to claim 6, wherein at least two blades are provided, which are set at a different angle α with respect to the corresponding inflow opening in such a way that the exhaust gas mass flow B through each of the inflow openings is evened out.

8. The mixer arrangement according to claim 1, wherein the mixer has a mixer wall, wherein the mixer wall has an evaporation section downstream of the injection section, which can be wetted with the additive.

9. The mixer arrangement according to claim 8, wherein an active heating element for heating the evaporation section is provided.

10. The mixer arrangement according to claim 8, wherein the mixer has a mixer wall and the bypass has a bypass channel, wherein, in the region of the evaporation section, the mixer wall at least partially forms the bypass channel, or the mixer wall at least partially adjoins the bypass channel or the mixer wall is at least partially joined to the bypass channel, so that a heat exchange can take place in each case between the mixer wall and the second portion A2 of the exhaust gas mass flow A.

11. The mixer arrangement according to claim 10, wherein a perforation of the mixer wall is provided in the evaporation section.

12. The mixer arrangement according to claim 10, wherein at least one elevated structure is provided on a first surface facing the bypass channel in the region of the evaporation section, and/or a second surface of the mixing wall of the evaporation section, which can be wetted with the additive, is smoothed.

13. The mixer arrangement according to claim 1, wherein a post-chamber is provided downstream of the mixer, in which post-chamber the first portion A1 of the exhaust gas mass flow A and the second portion A2 of the exhaust gas mass flow A can be combined, wherein the post-chamber has an outlet opening from which the exhaust gas mass flow A can be guided out of the mixer arrangement.

14. A method for operating a mixer arrangement for an exhaust gas system according to claim 1, having an inlet opening through which an exhaust gas mass flow A is guided, a mixer which has at least one inflow opening that is fluidically connected to the inlet opening, wherein at least one first portion A1 of the exhaust gas mass flow A is guided through the mixer via the at least one inflow opening, wherein the mixer has an injection device wherein an additive is injected into an injection section of the mixer by means of the injection device. a bypass having at least one throughflow opening which is fluidically connected to the inlet opening, through which a second portion A2 of the exhaust gas mass flow A is guided past the mixer, wherein there is provided a regulating body, wherein at least one flow cross-section in the mixer arrangement is varied by means of the regulating body so that a ratio V with $V=\frac{A2}{V1}$ is varied during the operation of the exhaust gas system.

15. The method for operating a mixer arrangement for an exhaust gas system according to claim 14, wherein the regulating body has an actuator by means of which the ratio V is varied such that a variance range ΔA1 of the first portion A1 of the exhaust gas mass flow A is minimized depending on at least one engine parameter.

Description

DRAWINGS

[0038] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0039] Further advantages and details of the disclosure are explained in the claims and in the description and depicted in the figures, wherein:

[0040] FIG. 1 shows a cross-section of the mixer arrangement,

[0041] FIG. 2 shows a cross-section through the mixing pipe and the bypass channel;

[0042] FIG. 3 shows a completely opened and closed position of the regulating body;

[0043] FIG. 4 shows a cross-section through the mixer wall at the height of the inlet openings;

[0044] FIG. 5 shows an exhaust gas system having the mixer arrangement.

[0045] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0046] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0047] According to FIG. 1, the mixer arrangement 1 has an antechamber 2, a mixer 3, a bypass 4, a regulating body 5 and a post-chamber 9.

[0048] An exhaust gas mass flow A can arrive in the antechamber 2 via an inlet opening 2.1. A first portion A1 of the exhaust gas mass flow A can flow into the mixer 3 from here via inflow openings 3.1 which are formed as longitudinal slits. A second portion A2 of the exhaust gas mass flow A can be guided by way of a throughflow opening 4.1 into the bypass 4.

[0049] In addition to the inflow openings 3.1, the mixer 3 has an injection device 3.2 on its face 3.13 by means of which an additive can be injected into the mixer 3. In addition, the mixer 3 has a mixer wall 3.4 which conducts the first portion A1 of the exhaust gas mass flow A. In an evaporation section 3.5 of the mixer 3, which is located downstream of the injection device 3.2, perforations 3.8 are provided, via which a part of the exhaust gas can arrive in the mixer 3 from the bypass 4. Further downstream of the perforations 3.8, an outflow opening 3.9 is provided, via which the first portion A1 of the exhaust gas mass flow A can open out into the post-chamber 9.

[0050] The regulating body 5 varies the second portion A2 of the exhaust gas mass flow A which can flow through the bypass 4. To this end, the regulating body 5, which is configured here as a movably supported flap, can vary the flow cross-section Q of the throughflow opening 4.1 by means of an actuator 5.1 so that a ratio V with

[00003]$V=\frac{A2}{V1}$

can be varied. An electrical control device 6 is coupled to the regulating body 5. Said electrical control device regulates the regulating body 5 via the actuator 5.1 depending on at least one engine parameter, in particular the engine load and/or the engine speed, an exhaust gas temperature and/or the exhaust gas mass flow A in such a way that a variance range ΔA1 of the first portion A1 of the exhaust gas mass flow A is minimized. In addition, the bypass 4 has a bypass channel 4.3 through which the second portion A2 of the exhaust gas mass flow A flows. The second portion A2 of the exhaust gas mass flow A arrives in the post-chamber 9 via an exit opening 4.2.

[0051] The first portion A1 and the second portion A2 of the exhaust gas mass flow A are combined in the post-chamber 9. The exhaust gas mass flow A leaves the mixer arrangement 1 via an outlet opening 9.1 of the post-chamber 9.

[0052] The openings are each indicated by the dashed lines.

[0053] In accordance with FIG. 2, the mixer 3 has an injection section 3.3 and an evaporation section 3.5. The injection section 3.3 is the chamber into which the injection device 3.2 injects an additive. The evaporation section 3.5 is provided downstream of the injection section 3.3. The injection cone of the additive is indicated by the dotted line. The inflow openings 3.1 are arranged around the injection section 3.3, wherein only one of the injection openings 3.1 is depicted for the sake of clarity. Likewise, only one opening of the perforation 3.8 is depicted. The injection cone widens so that the additive wets the mixer wall 3.4 on a second surface 3.11, consequently the inner side of the mixer wall 3.4, in the evaporation section 3.5. The dotted-dashed line illustrates the transition between the injection section 3.3 and the evaporation section 3.5 of the mixer 3.

[0054] The mixer wall 3.4 of the evaporation section 3.5 forms a part of the bypass channel 4.3 in an overlapping region 3.10. Therefore, a heat exchange between the bypass channel 4.3 and the mixer wall 3.4 is guaranteed.

[0055] The mixer 3 has elevated structures 7.1, 7.2 in the evaporation section 3.5. The structures 7.1, 7.2 are provided on a first surface 3.6 of the mixer 3, consequently the outer side of the mixer wall 3.4 which faces the bypass channel 4.3 in the overlapping region 3.10. The structures 7.1 are an integral part of the first surface 3.6 of the mixer wall 3.4. The structures 7.2, on the other hand, are configured separately from the first surface 3.6 of the mixer wall 3.4. In the overlapping region 3.10 on the first surface 3.6 of the mixer 3, an active heating element 8 for heating the mixer wall 3.4 is, in addition, provided. Downstream of the active heating element 8, the mixer wall is uneven, consequently corrugated. By means of these measures, the temperature of the mixer wall 3.4 can be additionally increased in the evaporation section 3.5 so that local cooling of the mixer wall 3.4 is avoided, which prevents the injected additive from being deposited.

[0056] In FIG. 3a, the regulating body 5 is depicted in a second position P2. In the second position P2, the regulating body 5 is completely opened and releases 100% of an effective flow cross-section Q of the throughflow opening 4.1. In contrast to this, in FIG. 3b, the regulating body 5 is shown in a first position P1 in which it completely seals the effective flow cross-section Q of the injection opening 4.1. In the closed position P1, the bypass 4 is bridged and the entire exhaust gas mass flow A flows through the mixer 3.

[0057] In accordance with FIG. 4, the mixer 3 has blades 3.7 which are each provided at the inflow openings 3.1. The blades 3.7 are each set at an angle α with respect to the inflow openings 3.1. This guarantees that the exhaust gas mass flow B through each of the inflow openings 3.1 is the same. As a result of this measure, the swirl axis of the swirl movement and the central axis 3.12 of the mixer 3 coincide, which additionally avoids additive being deposited.

[0058] The mixer arrangement 1 is provided in an exhaust gas system 14 in accordance with FIG. 5. The exhaust gas system 14 begins after an engine 11 in the exhaust gas system 14. The mixer arrangement 1 is placed downstream of the engine 11. A catalytic converter 12 is provided downstream of the mixer arrangement 1. The catalytic converter 12 can be an SCR and/or a SDPF. The exhaust gas mass flow A which is guided through the exhaust gas system 14 opens out into the surroundings U via the exhaust opening 13. The depicted components are fluidically connected via an exhaust pipe 15. The exhaust gas system 14 can have further components.

[0059] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.