Reductant delivery unit for automotive selective catalytic reduction systems - active cooling

Abstract

A reductant delivery unit (RDU) delivers supplied reductant (aqueous urea solution) to the engine exhaust system. The delivered reductant is transformed into ammonia which then reacts with the exhaust oxides of nitrogen in a catalytic environment to produce nitrogen and H20. The reductant must be metered to coincide with the amount of NOx present in the exhaust, and also present sufficient spray quality of the delivered fluid to promote good mixing of the ammonia with the exhaust gas. The RDU is a liquid-cooled, making the RDU suitable for very high temperature environment applications.

What is claimed is: 
     
         1 . An apparatus, comprising:
 a reductant delivery unit, comprising:
 an outer shell; 
 a liquid cooling cavity disposed within the outer shell; and 
 an injector substantially surrounded by the liquid cooling cavity; 
 wherein coolant is circulated into and out of the liquid cooling cavity to control the temperature of the injector. 
   
     
     
         2 . The apparatus of  claim 1 , the outer shell further comprising:
 an upper shield; and   a lower shield connected to the upper shield, the lower shield forming a portion of the liquid cooling cavity.   
     
     
         3 . The apparatus of  claim 2 , further comprising an inner sleeve, wherein a portion of the outer surface of the inner sleeve is connected to a portion of the inner surface of the upper shield and a portion of the inner surface of the lower shield, forming part of the liquid cooling cavity. 
     
     
         4 . The apparatus of  claim 3 , the injector further comprising:
 a solenoid portion substantially surrounded by the inner sleeve such that the inner sleeve separates the solenoid portion from the liquid cooling cavity, preventing coolant in the liquid cooling cavity from contacting the solenoid portion; and   a valve portion controlled by the solenoid portion, the valve portion having a lower valve body connected to a portion of the lower shield at a connection point, forming a portion of the liquid cooling cavity.   
     
     
         5 . The apparatus of  claim 4 , further comprising:
 a casing at least partially surrounding the lower valve body; and   an o-ring surrounding the casing, providing a sealing function between the o-ring and the casing;   wherein the o-ring is in contact with the inner sleeve, providing a sealing function between the o-ring and the inner sleeve, and a portion of the liquid cooling cavity is formed by the sealing function between the o-ring and the casing and the sealing function between the o-ring and the inner sleeve.   
     
     
         6 . The apparatus of  claim 2 , further comprising:
 an inlet hydraulic connector connected to the lower shield; and   an outlet hydraulic connector connected to the lower shield;   wherein coolant flows through the inlet hydraulic connector into the liquid cooling cavity and from the liquid cooling cavity out of the outlet hydraulic connector.   
     
     
         7 . The reductant delivery unit having active cooling of  claim 6 , wherein the inlet hydraulic connector is located at a different position relative to the injector compared to the outlet hydraulic connector. 
     
     
         8 . The reductant delivery unit having active cooling of  claim 6 , wherein the inlet hydraulic connector is an angled inlet hydraulic connector. 
     
     
         9 . The reductant delivery unit having active cooling of  claim 6 , wherein the outlet hydraulic connector is an angled outlet hydraulic connector. 
     
     
         10 . The apparatus of  claim 1 , further comprising a v-clamp flange circumscribing the outer shell, the reductant delivery unit mounted for use as part of an exhaust system using the v-clamp flange. 
     
     
         11 . The apparatus of  claim 6 , where in the v-clamp flange is used for mounting the reductant delivery unit to an exhaust manifold. 
     
     
         12 . A reductant delivery unit, comprising:
 an upper shield;   a lower shield connected to the upper shield;   an inner sleeve connected to the upper shield and the lower shield;   a liquid cooling cavity for receiving and circulating coolant, part of the liquid cooling cavity defined by the connection between the inner sleeve and the lower shield; and   an injector at least partially surrounded by the inner sleeve such that coolant in the liquid cooling cavity is prevented from contacting the injector;   wherein coolant flows into and out of the liquid cooling cavity, and coolant circulates through the liquid cooling cavity.   
     
     
         13 . The reductant delivery unit of  claim 12 , the injector further comprising:
 a solenoid portion;   a valve portion controlled by the solenoid portion; and   a lower valve body, the lower valve body being part of the valve portion;   wherein the lower shield is in contact with and connected to the lower valve body, forming a portion of the liquid cooling cavity.   
     
     
         14 . The reductant delivery unit of  claim 12 , further comprising:
 a casing at least partially surrounding the lower valve body; and   an o-ring surrounding and in contact with the casing, providing a sealing function between the o-ring and the casing;   wherein a portion of the inner sleeve substantially surrounds the o-ring, providing a sealing function between the inner sleeve and the o-ring.   
     
     
         15 . The reductant delivery unit of  claim 12 , further comprising:
 an inlet hydraulic connector connected to the lower shield; and   an outlet hydraulic connector connected to the lower shield;   wherein coolant flows through the inlet hydraulic connector into the liquid cooling cavity and from the liquid cooling cavity out of the outlet hydraulic connector.   
     
     
         16 . The reductant delivery unit having active cooling of  claim 15 , wherein the inlet hydraulic connector is located at a different position relative to the injector compared to the outlet hydraulic connector. 
     
     
         17 . The reductant delivery unit having active cooling of  claim 15 , wherein the inlet hydraulic connector is an angled inlet hydraulic connector. 
     
     
         18 . The reductant delivery unit having active cooling of  claim 8 , wherein the outlet hydraulic connector is an angled outlet hydraulic connector 
     
     
         19 . The apparatus of  claim 12 , further comprising a v-clamp flange circumscribing the outer shell, the reductant delivery unit mounted for use as part of an exhaust system using the v-clamp flange. 
     
     
         20 . The apparatus of  claim 19 , where in the v-clamp flange is used for mounting the reductant delivery unit to an exhaust manifold, and the coolant circulated through the liquid cooling cavity. 
     
     
         21 . A reductant delivery unit having active cooling, comprising:
 an upper shield;   a lower shield connected to the upper shield;   an inner sleeve, an outer surface of the inner sleeve connected to an inner surface of the upper shield, and an inner surface of the lower shield;   an injector having a solenoid portion an a valve portion;   a lower valve body connected to a portion of the lower shield at a connection point, the lower valve body being part of the valve portion;   a casing partially surrounding the lower valve body, the casing being part of the solenoid portion;   an o-ring in contact with the inner sleeve, the o-ring substantially surrounding the casing, providing a sealing function between the casing and the inner sleeve;   an inlet hydraulic connector connected to the lower shield;   an outlet hydraulic connector connected to the lower shield; and   a liquid cooling cavity formed by the connection between the inner sleeve and the lower shield, the lower valve body and the lower shield, the o-ring and the inner sleeve, and the o-ring and the casing;   wherein coolant flows from the inlet hydraulic connector into the liquid cooling cavity to provide a cooling function to the injector, and the coolant exits the liquid cooling cavity through the outlet hydraulic connector.   
     
     
         22 . The reductant delivery unit having active cooling of  claim 21 , further comprising a v-clamp flange connected to the lower shield, the v-clamp flange connecting the reductant delivery unit to an exhaust system. 
     
     
         23 . The reductant delivery unit having active cooling of  claim 21 , wherein the inlet hydraulic connector is closer to the lower valve body than the outlet hydraulic connector. 
     
     
         24 . The reductant delivery unit having active cooling of  claim 21 , wherein the inlet hydraulic connector is an angled inlet hydraulic connector. 
     
     
         25 . The reductant delivery unit having active cooling of  claim 21 , wherein the outlet hydraulic connector is an angled outlet hydraulic connector.