Diesel dosing unit having an anti-coking injector assembly, and methods of constructing and utilizing same

Abstract

A diesel dosing unit (DDU) is disclosed, having a fluid injector assembly. The fluid injector assembly includes a fluid injector and an attachment assembly attached to a downstream end of the fluid injector, the attachment assembly at least partly defining a fluid path in fluid communication with a fluid path of the fluid injector. The DDU further includes a DDU housing in which the injector assembly is disposed, the DDU housing being configured to directly attach to an exhaust pipe of a vehicle. The fluid injector assembly is dimensioned to largely match the dimensions of an existing injector of a reductant delivery unit (RDU) such that the DDU housing utilizes the housing of the existing RDU.

What is claimed is: 
     
         1 . A diesel dosing unit (DDU), comprising:
 a fluid injector assembly, comprising:
 a fluid injector comprising a first housing, a fluid inlet disposed at a first end of the first housing for receiving fluid, a fluid outlet disposed at a second end of the first housing for exiting fluid from the first housing, the first housing defining at least in part a fluid path through the first housing between the fluid inlet and the fluid outlet, the fluid injector further including an actuator unit and a valve assembly operably coupled thereto for selectively discharging fluid in the fluid path from the fluid outlet when the valve assembly is in an open state and for preventing fluid in the fluid path from exiting the fluid outlet when the valve assembly is in a closed state; and 
 an attachment assembly, comprising:
 a second housing having a first end attached or attachable to the second end of the first housing and a second end, the second housing at least partly defining a fluid path between the first end of the second housing and the second end thereof; 
 a seat fixedly disposed within the second housing; 
 an attachment assembly needle movably disposed within the second housing and including a first end portion, the attachment assembly needle movable between a first position in which the first end portion of the attachment assembly needle contacts and provides a sealing engagement with the seat of the attachment assembly so as to prevent fluid from exiting the second housing through the second end thereof, and a second position in which the first end portion of the attachment assembly needle extends outwardly from the second end of the second housing and is spaced from the seat of the attachment assembly; and 
 a spring member disposed within the second housing and coupled to the attachment assembly needle so as to bias the attachment assembly needle towards the first position thereof and prevent fluid in the second housing from exiting the second housing through the second end thereof, wherein when the valve assembly is in the open state, fluid in the fluid injector exits the fluid injector from the fluid outlet thereof and enters the fluid path of the second housing under pressure so as to cause the attachment assembly needle to overcome the bias of the spring member and move to the second position for allowing the fluid to exit the second housing from the second end thereof, and when the valve assembly is in the closed state, fluid in the fluid injector is prevented from passing into the fluid path of the second housing so as to cause the spring member to bias the attachment assembly needle to move to the second position and prevent the fluid from exiting the second housing from the second end thereof; and 
 
   a DDU housing in which the injector assembly is disposed, the DDU housing is configured to directly attach to an exhaust pipe of a vehicle.   
     
     
         2 . The DDU of  claim 1 , wherein the DDU housing is a housing of a reductant delivery unit (RDU). 
     
     
         3 . The DDU of  claim 2 , wherein the injector assembly is dimensioned to have a profile which matches a profile of an injector of an existing RDU, and the DDU housing is a housing for the existing RDU. 
     
     
         4 . The DDU of  claim 3 , wherein the DDU is a passively cooled DDU and the DDU housing includes a plurality of through-holes defined along the DDU housing. 
     
     
         5 . The DDU of  claim 3 , wherein the DDU is a passively cooled DDU and the DDU includes at least one gasket disposed downstream of the attachment assembly, relative to a direction of fluid flow through the injector assembly, the at least one gasket thermally isolating the injector assembly. 
     
     
         6 . The DDU of  claim 5 , further comprising a flange having a sidewall into which an end portion of the DDU housing is disposed, the flange including an inner surface extending in a radial direction, wherein the at least one gasket comprises a first gasket disposed between a downstream end portion of the attachment assembly and the inner surface of the flange. 
     
     
         7 . The DDU of  claim 6 , wherein the flange further includes an outer surface disposed in the radial direction of the DDU, and the DDU further comprises a second gasket disposed between the outer surface of the flange and a boss of the exhaust pipe of the vehicle. 
     
     
         8 . The DDU of  claim 3 , wherein the DDU is an actively cooled DDU and the DDU housing includes a coolant inlet for receiving a coolant, a coolant outlet for returning a coolant, and a coolant jacket in fluid communication with the coolant inlet and the coolant outlet, the coolant jacket defining a space around at a least a portion of the injector assembly. 
     
     
         9 . The DDU of  claim 3 , wherein the fluid injector comprises a gasoline port fuel injector, the gasoline port fuel injector and the attachment assembly defining a profile which matches the profile of the injector of the existing RDU. 
     
     
         10 . A diesel dosing unit (DDU), comprising:
 a fuel injector comprising a first housing, a fluid inlet disposed at a first end of the first housing for receiving fluid, a fluid outlet disposed at a second end of the first housing for exiting fluid from the first housing, the first housing defining at least in part a fluid path through the first housing between the fluid inlet and the fluid outlet, the fuel injector further including an actuator unit and a valve assembly operably coupled thereto for selectively discharging fluid in the fluid path from the fluid outlet when the valve assembly is in an open state and for preventing fluid in the fluid path from exiting the fluid outlet when the valve assembly is in a closed state;   an attachment assembly comprising a second housing having a first end attached or attachable to the second end of the first housing and a second end, the second housing at least partly defining a fluid path between the first end of the second housing and the second end thereof; and   a reductant delivery unit (RDU) housing in which the fuel injector and the attachment assembly are disposed, the RDU housing configured to directly attach to an exhaust pipe of a vehicle.   
     
     
         11 . The DDU of  claim 10 , wherein the attachment assembly further comprises:
 a seat fixedly disposed within the second housing;   an attachment assembly needle movably disposed within the second housing and including a first end portion, the attachment assembly needle movable between a first position in which the first end portion of the attachment assembly needle contacts and provides a sealing engagement with the seat of the attachment assembly so as to prevent fluid from exiting the second housing through the second end thereof, and a second position in which the first end portion of the attachment assembly needle extends outwardly from the second end of the second housing and is spaced from the seat of the attachment assembly; and   a spring member disposed within the second housing and coupled to the attachment assembly needle so as to bias the attachment assembly needle towards the first position thereof and prevent fluid in the second housing from exiting the second housing through the second end thereof, wherein when the valve assembly is in the open state, fluid in the fuel injector exits the fuel injector from the fluid outlet thereof and enters the fluid path of the second housing under pressure so as to cause the attachment assembly needle to overcome the bias of the spring member and move to the second position for allowing the fluid to exit the second housing from the second end thereof, and when the valve assembly is in the closed state, fluid in the fuel injector is prevented from passing into the fluid path of the second housing so as to cause the spring member to bias the attachment assembly needle to move to the second position and prevent the fluid from exiting the second housing from the second end thereof.   
     
     
         12 . The DDU of  claim 10 , wherein the fuel injector and the attachment assembly are dimensioned to have a combined profile which matches a profile of an injector of an existing RDU, and the RDU housing is a housing of the existing RDU. 
     
     
         13 . The DDU of  claim 10 , wherein the DDU includes at least one gasket disposed downstream of the attachment assembly, relative to a direction of fluid flow through the injector assembly, the at least one gasket at least partly thermally isolating the fuel injector and the attachment assembly from the exhaust pipe. 
     
     
         14 . The DDU of  claim 13 , further comprising a flange having a sidewall into which an end portion of the DDU housing is disposed, the flange including an inner surface extending in a radial direction, wherein the at least one gasket comprises a first gasket disposed between a downstream end portion of the attachment assembly and the inner surface of the flange. 
     
     
         15 . The DDU of  claim 14 , wherein the flange further includes an outer surface disposed in the radial direction of the DDU, and the DDU further comprises a second gasket disposed between the outer surface of the flange and a boss of the exhaust pipe of the vehicle. 
     
     
         16 . The DDU of  claim 10 , wherein the DDU is an actively cooled DDU and the RDU housing includes a coolant inlet for receiving a coolant, a coolant outlet for returning a coolant, and a coolant jacket in fluid communication with the coolant inlet and the coolant outlet, the coolant jacket surrounding the attachment assembly and at least part of the fuel injector.