Fluid injector

Abstract

An injector for controllably injecting a fluid into an exhaust stream having a housing that defines a chamber for storing the fluid and a metering orifice defined by an annular flow passage in fluid communication with the chamber. A valve member is movable between closed and open positions for controlling the flow of fluid from the chamber, through the annular flow passage, and into the exhaust stream.

1 . An injector for controllably injecting a fluid into an exhaust stream, the injector comprising:
 a housing defining a chamber for storing the fluid;   an orifice comprising an annular flow passage in fluid communication with the chamber; and   a valve member for controlling the flow of fluid from the chamber, through the orifice and into the exhaust stream.   
     
     
         2 . The injector of  claim 1 , wherein the annular flow chamber is interposed between the chamber and the valve member. 
     
     
         3 . The injector of  claim 2 , wherein the valve member comprises a valve head and valve seat formed in an outer surface of the injector that faces the exhaust stream and a valve head, the valve head being movable between closed position at which the valve head engages the valve seat and blocks fluid flow through annular orifice the and an open position at which the valve head is spaced away from the valve seat in the direction of the exhaust stream to permit fluid flow through the annular flow passage. 
     
     
         4 . The injector of  claim 3 , wherein valve member seals the orifice from exhaust gas flow when the valve member is in its closed position. 
     
     
         5 . The injector of  claim 3 , wherein the valve member further comprises a plunger for moving the valve head between its open and closed positions.