Exhaust gas flow mixer

1. A mixer for mixing an exhaust flow with a fluid injected into an exhaust pipe, the mixer comprising:

a tubular housing including a first end, a second end and a center portion positioned between the ends, the center portion having a reduced size in relation to at least one of the first and second ends, the tubular housing including circumferentially spaced apart apertures extending through the center portion between the first and second ends;

a first mixing element including a body having a first peripheral portion and a second peripheral portion opposite the first peripheral portion, the first peripheral portion being positioned within one of the apertures, the second peripheral portion being positioned within another one of the apertures, the peripheral portions being fixed to the housing; and

a second mixing element including a body having third and fourth peripheral portions, the third and fourth peripheral portions being positioned within others of the apertures and fixed to the housing, the second mixing element being spaced apart from the first mixing element.

2. The mixer of claim 1 , wherein the center portion includes a tab positioned adjacent to one of the apertures, the tab being coupled to the first mixing element such that the tab moves to account for a change in size of the first mixing element as temperature changes.

3. The mixer of claim 2 , wherein the apertures include an axially extending portion and spaced apart circumferentially extending portions, the first mixing element extending through one of the axially extending portions.

4. The mixer of claim 3 , wherein the first mixing element protrudes radially outwardly beyond an outer surface of the center portion.

5. The mixer of claim 4 , wherein one of the apertures is asymmetrical and the housing includes a face at the edge of the one aperture limiting a distance of axial insertion of the first mixing element within the housing.

6. The mixer of claim 2 , wherein the tubular housing and the tab are monolithically constructed as one piece.

7. The mixer of claim 1 , wherein the center portion is shaped as a circular cylinder.

8. The mixer of claim 1 , wherein the center portion is shaped as a non-circular cylinder.

9. The mixer of claim 1 , wherein the housing includes a leading collar portion and a trailing collar portion positioned on opposite sides of the center portion, the leading and trailing collar portions including outer cylindrical surfaces having a first size, the center portion including an outer cylindrical surface having a second size less than the first size.

10. The mixer of claim 1 , wherein the first mixing element extends parallel to the second mixing element.

11. The mixer of claim 1 , wherein the first mixing element includes a mixing fin extending at an angle to the body to change a direction of the exhaust flow.

12. The mixer of claim 11 , wherein the first mixing element includes a deflection element positioned upstream of the mixing fin at a location to be impacted by the injected fluid.

13. The mixer of claim 12 , wherein the deflection element includes a substantially planar portion extending substantially parallel to a direction of the exhaust flow and a correction fin extending at an angle to the exhaust flow direction.

14. The mixer of claim 13 , wherein the deflection element extends at an angle of substantially 30 degrees to a direction of exhaust flow upstream of the mixer.

15. The mixer of claim 14 , wherein the mixing fin extends at an angle ranging substantially from 40 degrees to 45 degrees relative to a direction of exhaust flow upstream of the mixer.

16. A mixer for mixing an exhaust flow with a fluid injected into an exhaust pipe, the mixer comprising:

a tubular housing including a leading collar portion positioned at an open upstream end of the housing, an opposite open end of the housing, and a center portion therebetween, the center portion having a reduced outer size and a reduced inner size as compared to the leading collar portion, the center portion including spaced apart apertures; and

a mixing element positioned within the housing and extending into two of the apertures, the mixing element being fixed to the center portion of the housing at locations adjacent each of the two apertures.

17. The mixer of claim 16 , wherein the housing includes a first flared portion interconnecting the leading collar portion and the center portion.

18. The mixer of claim 16 , wherein the apertures each include an axially extending portion and spaced apart circumferentially extending portions, the mixing element extending through one of the axially extending portions.

19. The mixer of claim 18 , wherein the tubular housing includes a trailing collar portion positioned at the opposite open end, the trailing collar portion including an increased inner size and an increased outer size as compared to the center portion.

20. The mixer of claim 19 , wherein the housing also includes a second flared portion interconnecting the trailing collar portion and the center portion.

21. The mixer of claim 20 , wherein the axially extending portion of the apertures includes a first end terminating within the center portion and a second end terminating within the second flared portion or the trailing collar portion.

22. The mixer of claim 18 , wherein the first end of the axially extending portion terminates at a stop face limiting an amount of axial insertion of the mixing element within the housing.

23. The mixer of claim 18 , wherein the circumferentially extending portions of one of the apertures are positioned on either side of a tab that is fixed to the mixing element.

24. The mixer of claim 23 , wherein the mixing element is free to move relative to the housing except at the tab and another tab.

25. The mixer of claim 16 , wherein an inner surface of the housing is cylindrically shaped and includes the reduced inner size.