Claims:We Claim

1. A mixer (10) positioned in the exhaust gas after treatment system (12), said mixer (10) comprising:
a mixer chamber (14);
a plurality of metallic plates (16) positioned within said mixer chamber (14) and secured to a wall of said mixer chamber (14);
a plurality of static mixer blades (18) positioned within the mixer chamber (14), wherein each of said plurality of static mixer blades (18) comprises an upper surface (20) and a lower surface (22) that is defined opposite to the upper surface (20) such that the lower surface (22) of each of said plurality of static mixer blades (18) is secured to each of said plurality of metallic plates (16), the upper surface (20) of each of said plurality of static mixer blades (18) adapted to be deflected by exhaust gas that impinges on each of said plurality of static mixer blades (18); and
wherein each of said plurality of static mixer blades (18) is adapted to be in a deflected position when exhaust gas at a low temperature and low mass flow rate impinges on each of said plurality of static mixer blades (18), the deflection of each of said plurality of static mixer blades (18) causes the exhaust gas that impinges on each of said plurality of static mixer blades (18) to be deflected to improve the ammonia uniformity index which helps in improving the nitric oxide conversion efficiency.

2. The mixer (10) positioned in the exhaust gas after treatment system in accordance with Claim 1, wherein a lower surface (22) of each of said plurality of static mixer blades (18) is secured to each of said plurality of metallic plates (16) by welding the lower surface (22) of each of said plurality of static mixer blades (18) to each of said plurality of metallic plates (16)

3. The mixer (10) positioned in the exhaust gas flow path (12) of the exhaust gas after treatment system in accordance with Claim 1, wherein each of said plurality of static mixer blades (18) is adapted to remain in a non-deflected position when exhaust gas at a high temperature and high mass flow rate impinges on each of said plurality of static mixer blades (18), the non-deflection of each of said plurality of static mixer blades (18) causes the exhaust gas that impinges on each of said plurality of static mixer blades (18) to be directed towards a selective catalytic reduction chamber that is positioned downstream from said mixer (10).

4. The mixer (10) positioned in the exhaust gas after treatment system (12) in accordance with Claim 1, wherein each of said plurality of static mixer blades (18) is manufactured from a shape memory alloy that is adapted to be deflected when exhaust gas at a low temperature and low mass flow rate impinges on each of said plurality of static mixer blades (18) that causes an increase in the nitric oxide conversion efficiency of exhaust gas by increasing a degree of mixing of ammonia that is injected from a dosing module with exhaust gas that flows through said mixer (10), and wherein each of said plurality of static mixer blades (18) that is manufactured from the shape memory alloy is adapted to remain in the non-deflected position when exhaust gas at a high temperature and high mass flow rate impinges on each of said plurality of static mixer blades (18) that causes the exhaust gas to be directed towards a selective catalytic reduction chamber that is positioned downstream from said mixer (10).

5. The mixer (10) positioned in the exhaust gas after treatment system (12) in accordance with Claim 1, wherein each of said plurality of static mixer blades (18) is adapted to be deflected by exhaust gas at a low temperature and a low mass flow rate that impinges on each of said plurality of static mixer blades (18), wherein an angle of deflection of each of said plurality of static mixer blades (18) when exhaust gas at the low temperature and the low mass flow rate impinges on each of said plurality of static mixer blades (18), that causes the exhaust gas that impinges on each of said plurality of static mixer blades to be deflected to facilitate increasing a nitric oxide conversion efficiency by increasing a degree of mixing of ammonia that is injected from said dosing module with exhaust gas that flows through said mixer (10).
, Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a plurality of static mixer blades that are manufactured by means of a high temperature shape memory alloy, and more specifically to a plurality of static mixer blades that are positioned within a mixer in the exhaust gas after treatment system.

Background of the invention
[0002] IN 202141033904 describes a deflector plate positioned in the exhaust gas after treatment system. The deflector plate comprises an upper surface, and a lower surface that is defined opposite to the upper surface. The lower surface of the deflector plate is secured to a canning. The upper surface of the deflector plate is adapted to be deflected by exhaust gas that impinges on the deflector plate. The deflector plate is adapted to be at a deflected position when exhaust gas at a low temperature and low mass flow rate impinges on the deflector plate. The deflection of the deflector plate causes the exhaust gas that impinges on the deflector plate to be directed towards an injector tip of a dosing module to reduce wall-wetting effect and possibility of urea deposit formation in the injector tip.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a plurality of static mixer blades that are manufactured by means of a high temperature shape memory alloy and are positioned within a mixer of an exhaust gas after treatment system.

Detailed description of the embodiments
[0004] A mixer 10 positioned in an exhaust gas after treatment system 12 is described. The mixer 10 comprises a mixer chamber 14, and a plurality of metallic plates 16 that are positioned within the mixer chamber 14 and secured to a wall of the mixer chamber 14. A plurality of static mixer blades 18 are positioned within the mixer chamber 14, wherein each of the plurality of static mixer blades 18 comprises an upper surface 20 and a lower surface 22 that is defined opposite to the upper surface 20. The lower surface 22 of each of the plurality of static mixer blades 18 is secured to each of the plurality of metallic plates 16, the upper surface 20 of each of the plurality of static mixer blades 18 adapted to be deflected by exhaust gas that impinges on each of the plurality of static mixer blades 18. Each of the plurality of static mixer blades 18 is adapted to be in a deflected position when exhaust gas at a low temperature and low mass flow rate impinges on the upper surface 20 of each of the plurality of static mixer blades 18. The deflection of each of the plurality of static mixer blades 18 causes the exhaust gas that impinges on each of the plurality of static mixer blades 18 to be deflected to improve the mixing of ammonia with exhaust gas and thereby improving the uniformity index on the face of selective catalytic reduction system.

[0005] Figure 1 illustrates a plurality of static mixer blades 18 that are each manufactured by means of a high temperature shape memory alloy and are positioned within a mixer chamber 14 of an exhaust gas flow path 12 of an exhaust gas treatment system. In the exemplary embodiment, a plurality of static mixer blades 18 for the exhaust gas flow path 12 of an exhaust gas treatment system is described. More specifically, the plurality of static mixer blades 18 of the mixer 10 are positioned upstream of a selective catalytic reduction chamber (not shown). A plurality of metallic plates 16 are positioned within the mixer chamber 14 and are each secured to a wall of the mixer chamber 14. More specifically, each of the plurality of metallic plates 16 are secured to the wall of the mixer chamber 14 by welding each of the plurality of metallic plates 16 to the wall of the mixer chamber 14. In an alternate exemplary embodiment, each of the plurality of metallic plates 16 are secured to the wall of the mixer chamber 14 by means of an adhesive that is known in the art. In the exemplary embodiment, a plurality of static mixer blades 18 are positioned within the mixer chamber 14, and are adapted to be deflected to improve the mixing of ammonia with exhaust gas and thereby improving the uniformity index on the face of selective catalytic reduction system (not shown).

[0006] In an exemplary embodiment, each of the plurality of static mixer blades 18 comprises an upper surface 20 and a lower surface 22 that is defined lower to the upper surface 20 and located below the upper surface 20. The lower surface 22 of each of the plurality of static mixer blades 18 is defined opposite to that of the upper surface 20. In the exemplary embodiment, the lower surface 22 of each of the plurality of static mixer blades 18 is secured within each of the plurality of metallic plates 16. More specifically, a plurality of openings defined in the fixed attachment of each of the plurality of metallic plates 16, herein referred to as the “metallic plate” is secured to the lower surface 22 of each of the plurality of static mixer blades 18 by welding the sidewall of each of the plurality of openings defined in the fixed attachment of each of the plurality of metallic plates 16 to the lower surface 22 of each of the plurality of static mixer blades 18. In an alternate exemplary embodiment, the sidewall of each of the plurality of openings defined in the fixed attachment of each of the plurality of metallic plates 16 is secured to the lower surface 22 of each of the plurality of static mixer blades 18 via any other means that is known in the art. The sidewall of each of the plurality of openings defined in the fixed attachment of each of the plurality of metallic plates 16 is secured to the lower surface 22 of each of the plurality of static mixer blades 18, while the portion of the fixed attachment of each of the plurality of metallic plates 16 is secured to a wall of the mixer chamber 14 by welding each of the plurality of metallic plates 16 to the wall of the mixing chamber 14.

[0007] In an exemplary embodiment, the opposite second end of the fixed attachment of each of the plurality of metallic plates 16 is secured to the wall of the mixer chamber 14 by welding the opposite second end of the fixed attachment of each of the plurality of metallic plates 16 to the wall of the mixer chamber 14. In an alternate exemplary embodiment, the opposite second end of the fixed attachment is secured to the wall of the mixer chamber 14 by welding.

[0008] In an exemplary embodiment, the upper surface 20 of each of the plurality of static mixer blades 18 is adapted to be in a deflected position due to the low temperature exhaust gas that impinges on each of the plurality of static mixer blades 18. More specifically, at lower temperatures, each of the plurality of static mixer blades 18 is in the martensite phase. When exhaust gas at a low temperature and low mass flow rate impinges on each of the plurality of static mixer blades 18, each of the plurality of static mixer blades 18 is adapted to be deflected such that the exhaust gas from the engine that impinges on each of the plurality of static mixer blades 18 is deflected. The deflection of the exhaust gas that impinges on each of the plurality of deflected static mixer blades 18 facilitates improving the mixing of ammonia with exhaust gas and thereby improving the uniformity index on the face of selective catalytic reduction system for better Nitric Oxide conversion efficiency. More specifically, at low mass flow rates and at low temperatures, the exhaust gas does not have sufficient resistance from the mixer to mix properly. Therefore, ammonia does not completely mix with the exhaust gas, thereby leading to an inefficient mixer. The defection in the angle of the plurality of static mixer blades 18 causes a more thorough mixing of the ammonia that is injected from the dosing module with the exhaust gas that flows through the mixer 10 as the static mixer blades 18 offers greater resistance to the flow of exhaust gas. Therefore, by deflecting the exhaust gas from each of the plurality of static mixer blades 18, Nitric Oxide conversion efficiency of exhaust gas is increased by increasing the degree of mixing of ammonia that is injected from the dosing module with the exhaust gas that flows through the static mixer blades 18.

[0009] In an exemplary embodiment, each of the plurality of static mixer blades 18 is adapted to remain in a non-deflected position when exhaust gas at a high temperature and high mass flow rate impinges on each of the plurality of static mixer blades 18. More specifically, when the high temperature and high mass flow rate exhaust gas impinges on each of the plurality of static mixer blades 18, the original martensite crystal structure of each of the plurality of static mixer blades 18 changes to an austenite phase. As a result, the internal crystal structure of the shape memory alloy alters, thereby changing the shape of each of the plurality of static mixer blades 18. Each of the plurality of static mixer blades 18 is not deflected when exhaust gas at a high temperature and a high mass flow rate impinges on the upper surface 20 of each of the plurality of static mixer blades 18. Therefore, due to the non-deflection of each of the plurality of static mixer blades 18, the exhaust gas that impinges on the upper surface 20 of each of the plurality of static mixer blades 18 is directed towards the selective catalytic reduction chamber that is positioned downstream from the mixer 10. The exhaust gas from each of the plurality of static mixer blades 18 is not specifically deflected upwardly. This is because the high temperature and high mass flow rate exhaust gas that flows out from the engine has sufficient mass flow to mix thoroughly, thereby enhancing the nitric oxide conversion efficiency.

[0010] In an exemplary embodiment, each of the plurality of static mixer blades 18 are manufactured from a shape memory alloy. More specifically, the shape memory alloy material of each of the plurality of static mixer blades 18 is adapted to be at a deflected position when exhaust gas at a low temperature and low mass flow rate impinges on each of the plurality of static mixer blades 18. More specifically, when exhaust gas at the low temperature and low mass flow rate is allowed to impinge on the upper surface 20 of each of the plurality of static mixer blades 18, the crystal structure of the shape memory alloy remains unchanged. When exhaust gas at the low temperature and low mass flow rate impinges on the upper surface 20 of each of the plurality of static mixer blades 18, each of the plurality of static mixer blades 18 are deflected to a higher degree by an angle, thereby deflecting the exhaust gas that impinges thereon. The deflection of the exhaust gas that impinges on the upper surface 20 of each of the plurality of static mixer blades 18 upwardly causes an increase in the nitric oxide conversion efficiency by increasing a degree of mixing of ammonia that is injected from the dosing module with exhaust gas that flows through the mixer 10. Each of the plurality of static mixer blades 18 that is manufactured from the shape memory alloy is adapted to remain in the non-deflected position when exhaust gas at the high temperature and high mass flow rate impinges on the upper surface 20 of each of the plurality of static mixer blades 18. More specifically, when exhaust gas at the high temperature and high mass flow rate are allowed to impinge on the upper surface 20 of each of the static mixer blades 18, the crystal structure of the shape memory alloy changes from the martensite phase to the austenite phase. When exhaust gas at the high temperature and high mass flow rate impinges on the upper surface 20 of each of the plurality of static mixer blades 18, each of the plurality of static mixer blades 18 are not deflected to any degree. The non-deflection of the static mixer blades 18 causes the exhaust gas that impinges on the upper surface 20 of each of the plurality of static mixer blades 18 to not get deflected. Rather, the exhaust gas that impinges on each of the plurality of static mixer blades 18 are directed towards a selective catalytic reduction chamber that is positioned downstream from each of the plurality of static mixer blades 18.

[0011] The angle of the upper surface 20 of each of the plurality of static mixer blades 18 causes the exhaust gas that impinges on the upper surface 20 of each of the plurality of static mixer blades 18 to be directed upwardly, thereby causing an increase in the nitric oxide conversion efficiency of exhaust gas. Due to the deflection of the exhaust gas in the upward direction, a degree of mixing of ammonia that is injected from the dosing module with exhaust gas that flows through the mixer 10 is increased substantially.

[0012] In an exemplary embodiment, each of the plurality of static mixer blades 18 is adapted to remain in the non-deflected position when exhaust gas at the high temperature and high mass flow rate impinges on each of the plurality of static mixer blades 18. More specifically, at the high temperature and high mass flow rate of exhaust gas, the crystal structure of the shape memory alloy of each of the plurality of static mixer blades 18 changes from a martensite phase to an austenite phase. As the phase of each of the plurality of static mixer blades 18 changes from the martensite phase to the austenite phase, it gets deflected back, thereby causing the exhaust gas to be channeled directly towards the selective catalytic reduction chamber that is positioned downstream from the mixer 10. The temperature at which the exhaust gas does not change the phase of the shape memory alloy of each of the plurality of static mixer blades 18 from the martensite phase to the austenite phase can be varied by the user by selecting a suitable material of the shape memory alloy. The application of the shape memory alloy-based static mixer blades 18 alters the temperature at which the exhaust gas changes the phase of the shape memory alloy of each of the plurality of static mixer blades 18 from the martensite phase to the austenite phase and the corresponding deflection of each of the plurality of static mixer blades 18.

[0013] In an exemplary embodiment, each of the plurality of static mixer blades 18 is adapted to be in a deflected position when exhaust gas at the low temperature and the low mass flow rate impinges on each of the plurality of static mixer blades 18. More specifically, when exhaust gas at the low temperature and the low mass flow rate impinges on each of the plurality of static mixer blades 18, the constant phase of the shape memory alloy of each of the plurality of static mixer blades 18 is retained. Therein, each of the plurality of static mixer blades 18 changes its angle of deflection when exhaust gas at the low temperature and low mass flow rate impinges thereon. The change in the angle of deflection of each of the plurality of static mixer blades 18 when exhaust gas at the low temperature and low mass flow rate impinges on each of the plurality of static mixer blades 18 causes the exhaust gas to be deflected upwardly by each of the plurality of static mixer blades 18, thereby causing an increase in the nitric oxide conversion efficiency of exhaust gas. Due to the deflection of the exhaust gas in the upward direction, a degree of mixing of ammonia that is injected from the dosing module with exhaust gas that flows through the mixer 10 is increased substantially.

[0014] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.