MIXING DEVICE

Abstract

A mixing device for integrating into an exhaust pipe of an internal combustion engine and for intermixing an exhaust gas flow T, which device is formed by a housing including a pipe wall for guiding the exhaust gas in a main flow direction H, an intermediate wall which at least partially delimits a flow cross section Qs of the housing, and by a mixing pipe, wherein: the mixing pipe has an injection nozzle for an additive to be incorporated, the nozzle being in the region of a first end E1 of the mixing pipe, and the mixing pipe is accommodated, in the region of a second end E2, in the intermediate wall; a perforation zone having a through-flow cross section Qp is provided at least between the injection nozzle and the intermediate wall; the intermediate wall and the mixing pipe 5 separate the housing into an inflow sector and an outflow sector; at least 90% of the gas to be guided from the inflow sector to the outflow sector can be directed through the perforation zone; a wedge-shaped flow-directing element having a directing nose is provided after the mixing pipe, which nose protrudes beyond the pipe wall and/or the intermediate wall and by means of which the exhaust gas flow T can be divided into two partial flows T1, T2; and wherein the partial flows T1, T2 can be brought into a counter swirl flow in relation to the main flow direction H.

Description

FIELD OF THE INVENTION

The invention relates to a mixing device for integrating into an exhaust pipe of an internal combustion engine and for intermixing an exhaust gas flow T, which device is formed by a housing comprising a pipe wall for guiding the exhaust gas in a main flow direction H and an intermediate wall which at least partially delimits a flow cross section Qs of the housing and by a mixing pipe, wherein the mixing pipe has an injection nozzle for an additive to be incorporated, the nozzle being in the region of a first end E1 of said mixing pipe, and the mixing pipe is accommodated in the region of a second end E2 in the intermediate wall, wherein a perforation zone having a through-flow cross-section Qp is provided at least between the injection nozzle and the intermediate wall, wherein the intermediate wall and the mixing pipe separate the housing into an inflow sector and an outflow sector, wherein at least 90% of the gas to be guided from the inflow sector to the outflow sector can be directed through the perforation zone.

BACKGROUND OF THE INVENTION

A mixing device is already known from U.S. Pat. No. 8,033,104 B2 for connecting an exhaust pipe of an internal combustion engine for mixing an exhaust gas flow. Said device has an intermediate wall on which a cylindrical mixing pipe with an injection nozzle opens out on the end side. The exhaust gas flow enters on the luff side of the intermediate wall through the perforation into the mixing pipe, and leaves the mixing pipe opposite the injection nozzle on the lee side of the intermediate wall.

Further, a mixing device for connecting an exhaust pipe of an internal combustion engine for mixing an exhaust gas flow is known from US 2010/0263359 A1. Said device has a cylindrical mixing pipe with an injection nozzle and with a perforation, which blocks the exhaust pipe in the manner of an intermediate wall up to the perforation. The exhaust gas flow enters on the luff side of the perforation into the mixing pipe, and leaves the mixing pipe opposite the injection nozzle on the lee side.

A mixing pipe for integration into an exhaust pipe is known from US 2015/0040537 A1, wherein the mixing pipe has a cylindrical section and conical section connected to this. In both sections, different recesses and openings are provided, through which the exhaust gas flows into the mixing pipe.

SUMMARY OF THE INVENTION

The object of the invention is to design and arrange a mixing device such that an improved mixing behavior is guaranteed.

The object is attained by means of the fact that after the mixing pipe, a wedge-shaped flow directing element is provided with a directing nose which protrudes over the tube wall and/or the intermediate wall, and by means of which the exhaust gas flow T can be divided into two partial flows T1, T2, wherein the partial flows T1, T2 can be brought into a counter swirl in relation to the main flow direction. Here, a first partial flow T1 is deflected in a counter-clockwise direction and a second partial flow T2 is deflected in a clockwise direction, so that an improved mixing of the exhaust gas flow with the additive and an improved feed flow into a downstream substrate such as a catalyzer or particle filter are achieved.

In this regard, it can be advantageous when the mixing pipe has an oval profile form F with a height h running along a main axis and with a breadth b running along an auxiliary axis, wherein the main axis is aligned transverse to the main flow direction H of the exhaust gas flow, with h>=1.2 b. The approach flow and inflow into the mixing pipe is improved through the use of the broader approach flow area. With the exception of smaller rinsing openings within the intermediate wall, preferably close to the housing wall, the entire exhaust gas flow must be guided through the mixing pipe.

Additionally, it can be advantageous when the following applies for the through-flow cross section Qp of the perforation zone in relation to the flow cross section Qs of the housing: 0.05 Qs<=Qp<=0.6 Qs or 0.07 Qs<=Qp<=0.5 Qs or 0.08 Qs<=Qp<=0.45 Qs. Thus, the standards for minimal flow losses on the one hand and for an advantageous acceleration and mixing of the exhaust gas flow on the other are met.

The object is also attained by means of an exhaust pipe with an integrated mixing device and an exhaust gas system with such an exhaust pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and details of the invention are explained in the patent claims and in the description, and illustrated in the figures, in which:

FIG. 1 shows a side view of the mixing device with opened housing 2;

FIG. 2 shows a profile view A-A according to FIG. 1;

FIG. 3 shows a principle sketch of the mixing pipe from above.

DETAILED DESCRIPTION OF THE INVENTION

A mixing device 1 shown in FIG. 1 has a housing 2 with a pipe wall 2.1, within which a mixing pipe 5 and a flow-directing element 6 are arranged. The housing 2 has an integral pipe adapter 2.4 in the area of the entrance opening, via which it is connected to an exhaust pipe 4.1 of an exhaust gas system, not shown. Also, the housing 2 is connected in the area of the outlet opening to an exhaust gas follow-up treatment housing 4.2, not presented in greater detail, of an exhaust gas treatment element.

An exhaust gas flow T flows via the exhaust pipe 4.1 in a main flow direction H into the mixing device 1 or the housing 2 and leaves said housing on the end side in order to flow out into the additional exhaust gas treatment housing 4.2.

A mixing pipe 5 is provided within the housing 2, which protrudes in a radial direction into the housing 2 in relation to the main flow direction H. An intermediate wall 3 adjoins the mixing pipe 5, which partially closes a flow cross section Qs of the housing 2. The exhaust gas flow T, which arrives at the luff side 3.1 of the intermediate wall 3 and at the mixing pipe 5, thus enters the mixing pipe 5 via a perforation zone 5.2 of the mixing pipe 5, and exits the mixing pipe 5 on the end side on the mixing pipe 5 (shown here towards the top). On a lee side 3.2 of the intermediate wall 3, a flow directing element 6 is located, via which the exhaust gas flow T exiting from the mixing pipe 5 is divided into two partial flows T1, T2.

In the profile view A-A shown in FIG. 2, it is demonstrated that the flow directing element 6 has a directing nose 6.1 which (here from the top) enters into the flow chamber in a radial direction to the housing 2 and generates a partial flow T1 running in a clockwise direction and a partial flow T2 of the exhaust gas flow running in an anti-clockwise direction. The flow directing element 6 is supplemented by a directing body 6.2 which is arranged opposite to the directing nose 6.1 in relation to the exhaust gas flow (here in the lower area), and to this extent limits the kidney-shaped directing channel of the mixing device 1. The intermediate wall 3 is an integral component of the flow directing element 6 in the lower area.

The exhaust gas flow T thus enters into the additional exhaust gas follow-up treatment housing 4.2 in two partial flows T1, T2 oriented in opposite directions.

Opposite an exit end or a second end E2 of the mixing pipe 5, an injection nozzle 5.1 is provided in the area of a first end E1, through which the additive is entered into the interior of the mixing pipe 5 for the purpose of retention through the exhaust gas flow T.

According to FIG. 3, the mixing pipe 5 has an oval profile, so that a medium inflow angle between the exhaust gas flow T and its main flow direction H and the mixing pipe wall with respect to the luff side of the mixing pipe 5 increases to approximately 90°. The mixing pipe 5 here has a ratio between the height h and the breadth b of approximately 1:4.

LIST OF REFERENCE NUMERALS

• 1 Mixing device
• 2 Housing
• 2.1 Pipe wall
• 2.2 Inflow sector
• 2.3 Outflow sector
• 2.4 Pipe adapter
• 3 Intermediate wall
• 3.1 Luff side
• 3.2 Lee side
• 4.1 Exhaust gas pipe
• 4.2 Exhaust gas pipe, exhaust gas follow-up treatment housing
• 5 Mixing pipe
• 5.1 Injection nozzle
• 5.2 Perforation zone
• 5.3 Main axis
• 5.4 Auxiliary axis
• 6 Flow directing element
• 6.1 Directing nose
• 6.2 Directing body
• b Breadth of 5
• E1 First end
• E2 Second end
• F Profile form of 5
• H Main flow direction
• h Height of 5
• Qp 5.2
• Qs Through-flow cross section 2
• T Exhaust gas flow
• T1 Partial exhaust gas flow
• T2 Partial exhaust gas flow

Claims

1. A mixing device for integrating into an exhaust pipe of an internal combustion engine and for intermixing an exhaust gas flow T, comprising: a housing comprising a pipe wall for guiding the exhaust gas in a main flow direction H and an intermediate wall which at least partially delimits a flow cross section Qs of the housing and by a mixing pipe, wherein the mixing pipe has an injection nozzle for an additive to be incorporated in the region of a first end, and is accommodated in the region of a second end in the intermediate wall, wherein a perforation zone having a through-flow cross-section Qp is provided at least between the injection nozzle and the intermediate wall, wherein the intermediate wall and the mixing pipe separate the housing into an inflow sector and an outflow sector, wherein at least 90% of the gas to be guided from the inflow sector to the outflow sector can be directed through the perforation zone, wherein after the mixing pipe, a wedge-shaped flow directing element is provided with a directing nose which protrudes over the pipe wall and/or the intermediate wall, and by means of which the exhaust gas flow T can be divided into two partial flows T1, T2, wherein the partial flows T1, T2 can be brought into a counter swirl in relation to the main flow direction H.

2. The mixing device according to claim 1, wherein

the mixing tube has an oval profile form F with a height h

running along a main axis and a breadth b

running along an auxiliary axis wherein the main axis is aligned

transverse to the main flow direction H of the exhaust gas flow, with h>=1.2 b.

3. The mixing device according to claim 2, wherein

the following applies to the through-flow cross section Qp of the perforation zone

in relation to the flow cross section Qs of the housing: 0. 05 Qs<=Qp<=0.6 Qs or 0.07 Qs<=Qp<=0.5 Qs or 0.08 Qs<=Qp<=0.45 Qs.

4. An exhaust pipe with an integrated mixing device according to claim 1.

5. An exhaust system with an exhaust pipe according to claim 4.

6. An exhaust pipe with an integrated mixing device according to claim 2.

7. An exhaust pipe with an integrated mixing device according to claim 3.

8. An exhaust system with an exhaust pipe according to claim 7.