Mixing pipe for SCR mufflers

1. An apparatus for treating exhaust, comprising:

a housing having a side wall, a top wall, and a bottom wall, the housing having an inlet and an outlet, the inlet in fluid communication with a source of exhaust gas;

a mixing chamber in the housing in fluid communication with the inlet;

a substrate chamber in the housing in fluid communication with the mixing chamber;

an outlet chamber in the housing in fluid communication with the substrate chamber and the outlet; and

a mixing loop comprising:

a first branch having a first proximal end connected to the inlet and extending into the mixing chamber;

a second branch having a second proximal end connected to the inlet and extending into the mixing chamber, wherein a plurality of apertures is defined in respective walls of the first branch and the second branch; and

an end section extending between respective distal ends of the first branch and the second branch, wherein the end section is devoid of apertures and closed to block the exhaust gas from being expelled through the end section and into the mixing chamber, and wherein the end section is curved and forms a 180 degree turn.

2. The apparatus of claim 1 wherein the apertures are evenly distributed in the respective wall of the first branch and the second branch.

3. The apparatus of claim 1 wherein the apertures are unevenly distributed in the respective wall of the first branch and the second branch.

4. The apparatus of claim 1 wherein the apertures are the same size.

5. The apparatus of claim 1 wherein the apertures vary in size.

6. The apparatus of claim 1 wherein the mixing loop has a third branch connected to the inlet and extending into the mixing chamber.

7. The apparatus of claim 1 further comprising an exhaust pipe connected to the outlet of the housing, a portion of the exhaust pipe extending into the outlet chamber, wherein the portion of the exhaust pipe extending into the outlet chamber includes a plurality of apertures defined in a wall of the exhaust pipe.

8. The apparatus of claim 1 wherein the at least two branches and the end section of the mixing tube form a mixing loop.

9. The apparatus of claim 8 wherein the mixing loop is ovular.

10. The apparatus of claim 1 , further comprising an inlet pipe connected to the inlet defined in the housing, the inlet pipe being in fluid communication with the mixing loop, wherein the inlet pipe and the mixing loop define a continuous flow path through the mixing chamber for the exhaust gas entering the housing via the inlet.

11. The apparatus claim 10 , wherein the inlet pipe and the mixing loop are formed integrally.

12. An apparatus for treating exhaust comprising:

a housing having an inlet and an outlet, the inlet in fluid communication with a source of exhaust, the housing defining a chamber;

a mixing tube having at least two branches, wherein respective proximal ends of the at least two branches are connected to the inlet and a plurality of apertures is defined in respective walls of the at least two branches, distal ends of the at least two branches being connected by an end section, wherein the end section is curved and forms a 180 degree turn and the end section is devoid of apertures and closed to block the exhaust from being expelled through the end section; and

a substrate disposed between the mixing tube and the outlet.

13. The apparatus of claim 12 wherein the apertures are evenly distributed in respective walls of the at least two branches.

14. The apparatus of claim 12 further comprising a mixing chamber in fluid communication with the inlet, the mixing tube extending into the mixing chamber.

15. An apparatus for treating exhaust, comprising:

a housing having a side wall, a top wall, and a bottom wall, the housing having an inlet and an outlet, the inlet in fluid communication with a source of exhaust gas;

a mixing chamber in the housing in fluid communication with the inlet;

a substrate chamber in the housing in fluid communication with the mixing chamber;

an outlet chamber in the housing in fluid communication with the substrate chamber and the outlet;

an inlet pipe connected to the inlet defined in the housing, wherein a center line of the housing extends through the inlet pipe and the mixing chamber; and

a mixing loop in fluid communication with the inlet pipe, wherein the mixing loop comprises a first branch having a first linear portion positioned on a first side of the center line and a second branch having a second linear portion positioned opposite the first linear portion on a second side of the center line wherein the first and second linear portions are parallel with respect to one another and are connected to the inlet pipe and extend into the mixing chamber, and wherein the mixing loop comprises an end section extending between respective distal ends of the first branch and the second branch, wherein respective walls of the first and second linear portions have a plurality of apertures, and the end section is devoid of apertures to block the exhaust gas from moving from the mixing tube into the mixing chamber at the end section,

wherein the inlet pipe and the mixing loop define a continuous flow path through the mixing chamber for the exhaust gas entering the housing via the inlet.

16. The apparatus of claim 15 , wherein the inlet pipe and the mixing loop are formed integrally.

17. The apparatus of claim 15 , wherein the end section is curved and forms a 180 degree turn.

18. The apparatus of claim 17 , wherein the mixing loop comprises a third branch extending into the mixing chamber along the center line.