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

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.