Ammonia flow modulator to prevent moisture build-up

Abstract

An ammonia flow modulator having a housing, a fluid passage, a first valve, preferably having a precision orifice, positioned within the passage, and an orientation which prevents fluid from pooling in the passage is disclosed and claimed. As an added feature, the device may include a heat source positioned within the housing proximate at least one of a fluid inlet, a fluid outlet, and the fluid passage. The heat source may be provided by an electric heating element, an exhaust gas heat exchanger, or any other suitable source. As econd inlet and a second passage fluidly connecting the second inlet to the outlet by fluidly linking the second passage to the first passage and including a check valve to prevent backflow. A controller coupled to the first valve is used to control ammonia flow.

What is claimed is: 
     
         1 . An ammonia flow modulator comprising:
 a housing having a first inlet and an outlet;   a first passage fluidly connecting the first inlet to the outlet; and   a first valve positioned within the passage for controlling a flow of ammonia to the outlet;   wherein the first passage is oriented such that gravity prevents fluid from being retained therein.   
     
     
         2 . The ammonia flow modulator of  claim 1 , wherein the first passage is entirely linear. 
     
     
         3 . The ammonia flow modulator of  claim 1 , wherein the first inlet of the housing is positioned superiorly to the outlet of the housing. 
     
     
         4 . The ammonia flow modulator of  claim 1 , further comprising a heat source within the housing. 
     
     
         5 . The ammonia flow modulator of  claim 4 , wherein the heat source comprises an electric heating element. 
     
     
         6 . The ammonia flow modulator of  claim 4 , wherein the heat source comprises a heat exchanger. 
     
     
         7 . The ammonia flow modulator of  claim 6 , wherein the heat exchanger is fluidly coupled to an engine exhaust flow. 
     
     
         8 . The ammonia flow modulator of  claim 1 , further comprising a second passage connecting a second inlet to the first passage. 
     
     
         9 . The ammonia flow modulator of  claim 8 , wherein the second passage is oriented such that gravity prevents fluid from being retained therein. 
     
     
         10 . The ammonia flow modulator of  claim 9 , wherein the second passage is substantially vertical. 
     
     
         11 . A reductant flow modulator comprising:
 a housing having a first inlet and an outlet;   a first passage fluidly connecting the first inlet to the outlet; and   a first valve positioned within the passage for controlling a flow of reductant to the outlet;   wherein the first passage is oriented such that gravity prevents fluid from being retained therein.   
     
     
         12 . The reductant flow modulator of  claim 11 , wherein the reductant is ammonia.