Tri-flow exhaust treatment device with reductant mixing tube

1. An exhaust treatment device, comprising:

a housing;

first and second substrates positioned in a parallel flow arrangement within the housing;

an inlet tube having a first end positioned outside of the housing and a second open end positioned inside of the housing;

an outlet pipe having a first end positioned outside of the housing and a second open end positioned inside of the housing;

a baffle plate supporting the substrates, the inlet tube and the outlet pipe, the baffle plate and a portion of the housing defining a first chamber, the baffle plate extending across upstream end faces of the first and second substrates and including apertures placing the substrates in fluid communication with the first chamber; and

a partition supporting the substrates, the inlet tube and the outlet pipe, the partition and another portion of the housing defining a second chamber separate from and spaced apart from the first chamber, second ends of the substrates and the second open end of the outlet pipe being in fluid communication with the second chamber, wherein all of the exhaust flowing through the treatment device flows in a first direction through the inlet tube, reverses direction to flow through the substrates and reverses direction again to flow through the outlet pipe.

2. The exhaust treatment device of claim 1 , wherein the baffle plate includes a circumferentially extending flange engaging the inlet tube.

3. The exhaust treatment device of claim 2 , wherein the baffle plate includes a first recess having a wall supporting the upstream end of the first substrate and a second recess having a wall supporting the upstream end of the second substrate.

4. The exhaust treatment device of claim 3 , further including a first can supporting the first substrate, wherein the wall of the first recess includes a plurality of circumferentially spaced apart slots in receipt of welds to the first can.

5. The exhaust treatment device of claim 1 , further including a mixer positioned with the inlet tube and an injector mount fixed to the inlet tube outside of the housing, the mixer being positioned within the housing and downstream of the injector mount.

6. The exhaust treatment device of claim 1 , wherein the housing includes an inner metal shell surrounded by insulation that is surrounded by an outer metal shell.

7. The exhaust treatment device of claim 1 , wherein the inlet tube is positioned adjacent to both of the first and second substrates to minimize heat loss from the inlet tube to the atmosphere.

8. The exhaust treatment device of claim 1 , wherein the baffle plate apertures include different sizes, the largest sized apertures being closest to the second end of the inlet pipe to increase the uniformity of exhaust flow through the substrates.

9. The exhaust treatment device of claim 1 , wherein the partition extends substantially parallel to the baffle plate.

10. The exhaust treatment device of claim 1 , wherein the first and second chambers are positioned at opposite ends of the treatment device.

11. An exhaust treatment device, comprising:

a housing;

first and second substrates positioned in a parallel flow arrangement within the housing;

an inlet tube having a first end positioned outside of the housing and a second open end positioned inside of the housing;

an outlet pipe having a first end positioned outside of the housing and a second open end positioned inside of the housing;

a first partition positioned within the housing and defining a portion of a first chamber, first ends of the substrates and the second end of the inlet tube being in fluid communication with the first chamber; and

a second partition positioned within the housing, spaced apart from the first partition, and defining a portion of a second chamber separate from and spaced apart from the first chamber, second ends of the substrates and the second open end of the outlet pipe being in fluid communication with the second chamber, wherein the inlet tube extends through the second chamber, the first partition, and the second partition, the inlet tube terminating at the first chamber, the first and second substrates having a gap therebetween, the gap being sized less than an outer cross-sectional dimension of the inlet tube, wherein the inlet tube is at least partially positioned within the gap and nested between the first and second substrates.

12. The exhaust treatment device of claim 11 , wherein the inlet tube is positioned adjacent to both of the first and second substrates to minimize heat loss from the inlet tube to the atmosphere.

13. The exhaust treatment device of claim 12 , wherein the first and second chambers are positioned at opposite ends of the treatment device.

14. The exhaust treatment device of claim 13 , wherein the housing includes an inner shell surrounded by insulation that is surrounded by an outer shell.

15. The exhaust treatment device of claim 14 , wherein the first partition includes apertures having different sizes, the largest sized apertures being closest to the second end of the inlet pipe.

16. The exhaust treatment device of claim 15 , wherein the first partition extends substantially parallel to the second partition.

17. The exhaust treatment device of claim 11 , wherein the first partition supports the first and second substrates.

18. The exhaust treatment device of claim 17 , further including a first can supporting the first substrate, wherein the first partition includes a plurality of circumferentially spaced apart slots in receipt of welds to the first can.

19. The exhaust treatment device of claim 11 , further including a mixer positioned with the inlet tube and an injector mount fixed to the inlet tube outside of the housing, the mixer being positioned within the housing and downstream of the injector mount.