Injector for reductant delivery unit having reduced fluid volume

A fluid injector, comprising:

• a fluid inlet disposed at a first end of the fluid injector for receiving a fluid, and a fluid outlet disposed at a second end of the fluid injector from which the fluid exits the fluid injector, the fluid injector defining a fluid path from the fluid inlet to the fluid outlet;
• an actuator unit, including a pole piece disposed in a fixed position within the fluid injector, a movable armature and a coil disposed in proximity to the pole piece and the movable armature;
• a valve assembly comprising a valve seat disposed at or in proximity with the second end of the fluid injector and a seal member connected to the armature and engageable with the valve seat;
• a volume reduction member disposed between the actuator unit and the fluid inlet, the volume reduction member including a bore defined through the volume reduction member, the bore partly defining the fluid path through the fluid injector;
• and
• one or more body portions in which the actuator unit, the valve assembly and the volume reduction member are disposed,
• wherein each of the actuator unit, the valve assembly, the volume reduction member and the one or more body portions comprising one or more components of the fluid injector, and a ratio of a volume of the fluid path to a volume of the components of the fluid injector is between 0.08 and 0.30,
• wherein the actuator unit further comprises a spring having a first longitudinal end contacting the armature and a second longitudinal end, and a spring adjustment member having a first end contacting the spring and a second end contacting a downstream end of the volume reduction member, the spring adjustment member including a throughbore partly defining the fluid path of the fluid injector, and
• wherein the fluid injector further comprises an elastic member disposed between and contacting the volume reduction member and the pole piece, the elastic member being constructed from compressible material and is in a compressed state between the pole piece and the volume reduction member, the elastic member surrounding a portion of the spring adjustment member and contacting the spring adjustment member portion.

A fluid injector for a reductant delivery unit, comprising:

• a fluid inlet disposed at a first end of the fluid injector for receiving a reductant, and a fluid outlet disposed at a second end of the fluid injector from which the reductant exits the fluid injector, the fluid injector defining a fluid path from the fluid inlet to the fluid outlet;
• an actuator unit, including a pole piece disposed in a fixed position within the fluid injector, a movable armature and a coil disposed in proximity to the pole piece and the movable armature;
• a valve assembly comprising a valve seat disposed at or in proximity with the second end of the fluid injector and a seal member connected to the armature and engageable with the valve seat;
• a volume reduction member disposed between the actuator unit and the fluid inlet, the volume reduction member including a bore defined through the volume reduction member, the bore partly defining the fluid path through the fluid injector;
• and
• one or more body portions in which the actuator unit, the valve assembly and the volume reduction member are disposed,
• wherein the actuator unit further comprises a spring having a first longitudinal end contacting the armature and a second longitudinal end, and a spring adjustment member having a first end contacting the spring and a second end contacting a downstream end of the volume reduction member, the spring adjustment member including a throughbore partly defining the fluid path of the fluid injector,
• wherein the fluid injector further comprises an elastic member disposed between and contacting the volume reduction member and the pole piece, the elastic member being constructed from compressible material and is in a compressed state between the pole piece and the volume reduction member, the elastic member surrounding a portion of the spring adjustment member and contacting the spring adjustment member portion.